1. De-slotting: How does the car come off the track?
2. Power: Does the car appear to be getting proper power?
1. Setting the Vertical Center of Gravity
2. Magnet Tuning
3. Weight Tuning
4. Selecting Gear Ratios
5. Motor Selection
6. Tire Selection
7. Chassis Weight Reduction, Guide Shoe Modification and Chassis Strengthening
8. Putting It All Together
9. Configuration Diagrams: move to the end
2. Removing the Brake Function.
Appendix 1: Car Chart - This is now deleted. See section for explanation.
Appendix 5: Tools List will be added at some point in the future
Appendix 6: Tire interchangability chart to be added in next update(hopefully)
When you first get a new plastic chassis slot car, no matter what the manufacturer,
there are a few things that can be done to improve its performance. What
we have tried to do in this article is provide a good basic reference checklist
that can be used to prepare these cars. There are also sections on race
tuning, repair and a couple of other items that may be of interest.
If you plan on race tuning your car you should do these steps where applicable
during the basic checklist part of the article. The tips we have provided
don't comply with any particular set of racing rules so you, the reader,
should make sure that any changes you make to your car meets the standards
set by your particular club or commercial track. The things we suggest
are only items that we have personally tried and that work for us. Throughout
the article you may notice the names of stores, Internet sites and manufacturers.
These are mentioned only as examples of where you can obtain certain items;
they are not recommendations or advertisements. As a final note before
we get down to it, we would like to apologize in advance for the lack of
pictures. At the time this article was written we didn't have a digital
camera. Perhaps we will add these items in the future.
1. General Inspection and Disassembly Back To Index
a. First prior to removing the body from the chassis, check to see if there is any rubbing between the tires and the body. This can occur for a number of reasons on certain cars but for now look for out of round wheels/tires, unseated axle bushings loose wheels and make note for later repair.
b. Check the guide for unimpeded movement throughout its turning radius. Binding could indicate improper installation/seating, plastic mold "flash" causing interference or lubrication requirement, which will be accomplished after chassis removal. Make notes for repair at the applicable time.
c. Look for obvious defects such as improperly installed/stripped screws (cross threaded) or a warped chassis/ body. Stripped screws can be repaired by rebushing the stripped post with glue and re-taping the screw. Warped chassis and bodies can usually be fixed by running hot water over the warped component and gently bending into shape. A hair dryer on a low setting can also be used.
d. Now remove the chassis asssembly from the body, watching to see if any parts fall out when the chassis and body are separated. This may sound amusing but believe me several of the cars I've purchased have had various parts come bouncing out the first time I opened the car up. So be observant and watch for this so that you won't have to spent time trying to figuring out where some doodad or such came from.
e. Now that you have the car separated, put the body aside and lets begin with the chassis assembly.
f. Remove all components from the chassis including the wheels, axles, guide, motor, and bushings. This is where you make sure the chassis is not warped or damaged. As we mentioned earlier, warped chassis can usually be fixed by putting it under hot water and gently straightening it.
2. Guide Shoe and Braids Back To Index
a. Check guide hole and axle/bearing holes for molding "flash" and remove as necessary. Reinstall the guide shoe. I use a small dab of silicone grease (DC-11) here to help freedom of movement.. If you will be doing any trimming on shortening of the guide, I recommend that you wait until the wheels are installed so that all the references for this task are in place.
b. Make sure that the guide turns freely with the motor wires connected (step 3e.) and that the wires are routed such that they provide self centering for the guide shoe. This can usually be accomplished by "x" crossing the cables at the guide and/or by taping them to the chassis so that they provide spring flexing to the guide shoe. Scalextric cars have spring loaded contact between the braid and the motor leads. It is not self centering and some people replace this system with an SCX/Ninco guide which can be wired like the these types of cars with new motor wires and eyelets. We generally leave the newer SCX "suspension" guides alone since we haven't figured out a good way to make them self centering. On these guides make sure that the springs are making proper contact with the guide. You may want to add a very small piece of plastic tubing between the guide holder and the guide on the SCX cars so that the guide bounce is reduced slightly. This will help to prevent deslots in the corners. Also a small dab of superglue under each braid on top of the guide will keep them from coming loose from the guide at an inopportune time. If the car is not new check for arcing between the spring contacts and the braid. This will show up as black carbon deposits on the tops of the braid. Arcing could indicate inproper contact pressure between the spring contacts and the guide braid. Adjust the springs for more down pressure if you suspect this problem.
c. Consideration should be given to replacing guide braids with the soft thin type made by companies such as Pink Kar and Slotit. They make the front end of the car lower to the track. Braids should be cut to the same length as the guide and "combed" to provide a spread out configuration, slightly bend down at the end. Combing can be done using a soft wire brush and gently seperating the braid at the track contact end. By using the capacitor mod in the Electrical Mods Section of this article you can reduce the effect of improper guide braid to rail contact.
d. One problem which all plastic chassis cars have to some extent is guide pin slop. There are several ways to improve the situation. One way is to thread a nut and washer to the guide pin and run it down to take up the excess movement. Another more detailed method is to fit the guide with a piece of brass tubing and glue it to the pin. Next drill out the guide hole to get an exact fit. You may want to reinforce the outside of the guide hole assembly with a glued piece of plastic tubing. You can now thread the brass tubing to take a lock nut and washer to prevent up down movement. A third simple method which works on most of the guides is to take one or two flat washers (3mm inside diameter) and press fit them on top of the post. Push them down to take up the slop, but not binding, and put a drop of super glue on them to secure. There are other methods to solve this problem with but these 3 examples work well for us. Take a look at the Chassis Weight Reduction and Guide Shoe Modification Section to get more info about fixing this problem. REMEMBER: this area takes quit a bit of abuse and stress so be careful not to weaken the overall structure here.
* Note: You should not do any rear axle bushing, wheel, pinion, or motor/mount gluing until after you have worked out and tested gear ratios. This process entails axle swapping. If you are planning to race tune the gear ratios you should hold off on the gluing until after final gears are selected and mounted.
3. Motor Procedures Back To Indexa. If you are using a stock motor you can remove any resistors, capacitors, or inductors that are soldered on to the motor leads. This will eliminate one area of possible electrical failure. On cars like Carrera thought should be given to removing all the switchology and EMI components and making simple motor to guide connections. These items have a habit of failing at the most inopportune time and could cost you a race win so take that junk off. Be advised that removing these items may cause your cars to interfere with TVs and other electronic devices. Component failures usually occur when components are being run at 15+vdc which exceeds the design limits on some brand cars EMI components.
b. Insure that the motor leads are properly soldered to the motor. Cold solder joints appear as a dull silver color and can rob your motor of power and cause intermittent power problems. Reheat any suspicious joints. On SCX RX-type motors the plug in leads should be soldered in place to prevent accidental disconnects. One additional item you should consider doing at this point is to isolate motor cable flex away from the motor attach points. This can be simply done by tapeing the cables to the chassis so that all of the movement occurs forward of the tape. This will lengthen cable life because one prime area of failure is cable breakage at the motor mounting points.
c. Make sure the pinion gear you plan to use is securely installed. If you are in doubt you can add a drop of super glue or, in the case of a brass pinion, super glue or solder. Always use a pinion tool for pinion installation/removal such as Ninco Part #70201. This will reduce the possibility of motor damage. When using high torque motors it is better to use solder on brass pinions to prevent "throwing a pinion" during a race. If you notice your car slowing for no particular reason during normal running, especially under acceleration, you may want to check to make sure the pinion is 100% secure. Sometimes it can loosen slightly and go unnoticed except when it is closely inspected. Increased lap times is one symptom of this problem. Brass or solder powder around the pinion area of the motor can be another indication that the pinion is slipping and wearing away slightly.
d. Reinstall motor and motor adapters as applicable. If your rules allow, glue these items in place so that neither the adapters nor the motor moves in the chassis. Depending on the difficulty in accessing motor bearings, you may want to lightly lubricate these items at this point with a light machine oil. Be careful not to over lubricate these bearings because you can foul the commutator. If you are using motor mounts make sure that the motor is sitting squarely in the chassis before final gluing. A twisted motor could "bottom out" on the track on low clearance cars. Also make sure motor adaptors have holes to allow motor bearing lubrication. If they do not, as in the case of Cartrix SCX adaptors, simply drill a lube hole in the adaptor. This will enable you to lube the bearings without having to remove the motor.
e. Make sure the motor leads plug into the guide securely. I put a drop of conductive paint/adhesive (used for car rear window defroster installation/repair) on each connection. This paint/adhesive is also useful on other electrical connections which could come loose such as motor to copper conductor strips on newer SCX cars. This is an alternative to soldering, which could melt the plastic and damage a good chassis. One type I use is CircuitWorks Conductive Epoxy. (view online at http://www.action-electronics.com/chemtron.htm ). If your careful you can also solder all these connections which will give them good contact and security.
4. Axles and Bearings Back To Index
a. Next comes the axles / bearings. Check for straightness of axles by rolling them on a flat smooth surface and observe any wobble that would indicate a bent axle. Usually a bent axle should be replaced unless you determine that it can be lived with. Remember high down-force magnet cars are less affected by axle/wheel balance problems than low down-force or no magnet cars but it is still a factor in overall performance especially on high speed tracks. Most Euro-cars have relatively soft axles which can easily be bent in a strong impact accident. Consideration should be given to upgrading to hardened steel replacements especially on the rear. Slot-it axle kits (see at:www.slot.it) offer strong replacements with better gear and aluminum wheels. If your budget permits these are good upgrades. On front axles you may want to go to Aluminum or Brass tubing if you have magnets mounted near the axle. This will reduce the flux line braking effect of the magnets on the axles and will reduce rotational mass.
b. Put a dab of glue (super glue works well) in each bearing carrier and, for inline motors, reinstall the rear axle / bearing assembly making sure the axle turns freely in the bearings. Some people advocate using a small amount of super glue in the bearing to tighten the tolerance of the axle to bearing surface. We've found this works okay on metal bushings but doesn't last for many races. If you want to try it then, first put a drop of glue in the bushing holes. One note: Glue the bushings to the chassis before trying to tighten up the axle slop because they might become attached to the axle and begin spinning in the bearing holders. Now, put a drop of oil or WD-40 on the axle and spread it over the entire axle. Insert the axle into the bushings and align before glue sets. After glues sets gently turn the axle to make sure it's free turning. Put a little more lubricant on the axle. That's it. There should be less free play. If you screw up here, you can use Acetone (used in most fingernail polish removers) to dissolve most CA-super glues. What I usually do instead of using this glue method is to paint the axles where they will be riding in the bushings with thin liquid dry film lubricant, not grease, (Molykote- Molybdenum disulfide ) and let it dry. When dry, it bonds to the axle and adds just the right amount of diameter increase to the axle in the bushing to remove excess bearing slop. With greater bushing tolerances you may need to apply several coats letting them dry between coats. Depending on the spec of the coating you use, it should wear longer and be slipperier than the super glue method. For sidewinder motor cars don't leave the axle /spur gear assembly installed at this time. This assembly is covered later in this section.
c. There are several designs for front axles. Generally though, axles should turn freely. A drop of lubricant may be added to the front axle attachment points to help to reduce wear. Ideally, you want the front tires to just barely touch the track when the car is at rest. Some cars use a stiff front axle set up. On these cars, it is very important to reduce the rolling friction of the front tires (step 5c). On FLY independent rotating wheels, if they are overly sloppy, take each axle and clip about 1 mm off the end This will allow the axle to be press fit on the wheel so that it will have zero slop with the axle carrier. Insert the axle into the carrier like you would for installation. Put some lubricant into the carrier hole so that super glue will not stick. Take the wheel and put super glue into the axle hole. Be careful not to put too much because you don't want any on the rear of the hub. Now press the hub onto the axle so that it is tight WITHOUT binding. Let the glue set up and this should be all you need. I usually turn the wheel as the glue sets up so that it doesn't wick into the carrier hole. The lubricant on the axle should prevent this. Your wheel assemblies should now be installed correctly and will not be rubbing any body parts or making any noise because of slop. Much later in the cars life when the axle carriers wear due to use you can drill out the carriers and install brass tubing inserts. The key to the whole thing is the fact that the axles are a little too long to snugly fit some wheels to the car. One other method is to use thin metal/plastic washers to take up this extra slop. These are several solutions to the loose front wheel problem so you can choose which method best suits your needs.
d. Solid front axle assembly problems usually show up in several ways. First your car will sometimes unexplainably de-slot in a turn with the car going straight off, not a spin. What has happened here is that something has caused front wheel binding resulting in the front end "hopping" out of the slot. Check for tire rubbing against the body/chassis or sharp tire edges grabbing the track. If you don't see anything obvious, try removing the front tires and running a few laps. Does the problem improve or go away. If so, go to the next step. If not try some weight up front. The second most common front end problem is the car acting sluggish in the turns. This is a too much rolling friction problem. Again remove the front tires and run a few laps. The situation should improve. To correct this problem go to the next step. Finally, sometimes the car floats or even de-slots on the straights. Usually softer guide braids or a little weight up front will cure this problem. More details on de-slotting are provided in the OBSERVATION section of this article.
5. Wheels and Tires Back To Index
a. Check all the wheel rims and tires for roundness and remove any casting residue with an x-acto knife. Then carefully install the tires, making sure that they are completely seated. If you are using soft rubber or silicone in combination with a high RPM motor consideration should be given to gluing the tires to the wheels. Silicone adhesive and rubber cement work well and generally don't damage the wheel. Contact / plastic cement may be used but be prepared for a possible one time replacement use of the wheel. Out of round wheels are not uncommon on some of cars and other than replacement the only thing you can do is try to remove some of the imbalance when sanding the tires. If your car will be running a lot of magnet downforce and or a high performance motor, you need to reinforce your wheel axle insert areas with plastic or brass tubing at this point. This will prevent them from cracking and the wheel separating under racing conditions. Additionally, If your going to be using high magnet downforce and hot motors in your car you may want to consider going to aluminum wheels such as Slotit or Pattos. These will give you better durability and won't break during hard impacts. You need to weigh the added cost and see. Remember it won't take many broken wheels to justify the added expense of the aluminum ones. You should be able to find proper inserts for these wheels so that your car doesn't suffer appearancewise.
b. Install each wheel on an old axle (straight) and place in a drill / dremel tool or such. Run at low speed and "round" the assembly by lightly applying the assembly to a flat piece of sandpaper or a sanding block. You should correct major roundness defects here. For front tires, I also find it better to sand off all tread patterns from the tires because you want a smooth non grip surface. After the assemblies are round, sand the inside and outside edges of the tire to round them off. This will help to prevent the tires from digging into the track surface and causing a premature de-slot or flip over in the turns. For the rear wheel/tire assemblies final rounding of the wheel assembly can better be carried out after installation by running the car at low speed with the rears raised off the track, placing a sheet of sandpaper flat on the track under them, lowering the rear while holding the front end and letting the tires sand themselves round. Edges will then need to be rounded using a small sanding block or similar. NOTE: Wheel assembly gluing (step 5d) should be carried out prior to final balancing so that minor deficiencies caused by wheel to axle rotation can be corrected.
c. If you want to lower the friction of the front tires to the track, and the rules allow, you can put nail polish (clear) or model cement on the tire treads to harden them and cause them to slide better. If you want to get real tricky and think you can slip it past the inspectors try this: Get some hair thin 12-15mm o-rings Dip them in nail polish and slip them on over your front tires to the high point, usually the center. Allow them to dry and you've got stealth hardened o-ring tires. When done correctly these o-rings look like tire mold residue. On the track, only the small "bump" of the o-ring will touch, greatly reducing rolling friction Consideration may also be given to the possible advantages of installing smaller diameter front tires, such as Pink Cars 16.5mm type (P/N RV003). These tires may also help the car maintain speed in the turns and reduce de-slots on cars where the front wheel assembly, rather than the guide shoe, supports any of the front end weight. A better solution in this case might be independent rotating front wheels or raising the axle. Sometimes slightly filing the plastic axle carriers to elongate the holes removes chassis weight from the front wheels and transfers it to the guide shoe. Be careful that you don't make the situation worse by allowing the tire to touch the inside of the body (step 7a).
d. After you've finalized all drive train alignment and gear selection and you don't expect to have to remove the wheels again the last thing you should do is glue the wheel assemblies to the axles both front and back. What I usually do is rough up the axle end using sandpaper or dremel being careful not to remove too much metal/plastic. This gives the glue a better "biting" surface. Then I add a drop of super glue to the axle end and press on the wheel assembly to the right position. If the wheel assembly is to be mounted other than all the way on the axle be sure to mark the axle so you know how far to press it on. Remember super glue sets up quickly so you need to get this right the first time. If you are in doubt about your ability to do this correctly there are slower set up time super glues that you can find at your local hobby store. If you balanced the wheels before you did this step be sure to mark the axle /wheel with a scribe before removal for gluing so that you can reassemble them in exactly the same position. After you've completed the gluing procedure you should check the wheel alignment and balance again and correct any deficiencies caused by the gluing. It is probably better to spin balance the rear wheel assemblies after gluing. For high downforce configured cars using stock wheels we recommend reinforcing the wheel axle holders with tubing either plastic or metal. Take a look at the Wheel drawing for additional details.
6. Aligning the Drive Train Back To Index
a. Now to the rear wheels/tires on the inline drive train. On these drive trains the self aligning crown gear takes a lot of the slop out of the axle. However, on most models it may be beneficial to add washers or spacers between the axle bushings and the wheel to take up any extra slack. This will reduce drive train noise dramatically and make the gears mesh better. When you are satisfied with this setup and have finished any gear selection work you can accomplish wheel assembly gluing (step5d). I also add a small drop of super glue to the crown gear to axle joint to reinforce this joint. Be careful that the glue doesn't wick into the axle bushings. Also a dab of silicone or white Moly grease on the self align slot will reduce friction. One note of caution here: It is usually better to remove and replace inline axle assemblies with the motor removed first because of the possibility of damaging the plastic crown gear. If you do choose to remove and replace the axle assembly with the motor installed be extremely careful that the pinion gear teeth don't damage the crown teeth.
b. On sidewinder drive cars washers should be added to first, provide clearance between the pinion gear and the tire on that side, second, keep the spur gear from rubbing on the chassis cutout, and third, to take up the slack in the axle assembly. This may sound complex but it can be done quite easily using thin washers and first centering the spur gear in the chassis cutout using a washer between the spur gear and the axle bushing then adding thin washers to get proper wheel clearance on the spur gear side of the axle (check for body to wheel clearance at this time also). After this wheel is set up, add washers to the other side of the axle to take up the overall slack and to position the opposite wheel assembly in the proper place. When you are satisfied with this setup and have finished any gear selection work you can accomplish wheel assembly gluing (step5d). I also add a small drop of super glue to the spur gear to axle joint to reinforce this joint. Again, be careful that the glue doesn't wick into the axle bushings. One mod to the chassis on cars such as FLY sidewinders that you might want to consider here is to cut out the spur slot in the chassis so that gear/axle assemblies may be removed without removing the pod first. This can save time and wear and tear during gear - axle changes.
c. One problem that many people complain about is gear noise. This can be caused by several factors and may be different sounds which we will try to explain.
1.) The first type of noise is a ticking sound that varies with speed. This is usually caused by a plastic gear that has one or more small burrs on the gear teeth. If you slowly rotate the axle you can usually feel the place where the binding is occurring and if you take a magnifying glass under strong light you will see the burr. You can usually correct this problem by taking a very sharp x-acto knife and shaving off the burr. The main cause of these burrs is not being careful when removing the motor or rear axle. The metal pinion acts like a knife and cuts into the soft plastic of the crown or spur gear.
2.) The second noise is a constant thrashing sound that may be caused by several things. If you are using Slotit pinions they are usually noisy in this way because of their design to get different amounts of teeth into the same diameter gear. You may also get this noise if the mesh is too tight. Sometimes new gears are noisy because they haven't seated themselves. In the case of the Slotits and the new gears you can add some paint rubbing compound to the gears and run them at low speed, being careful to cover the rest of the chassis so you don't create a mess (I use a small plastic bag and rubber band). This will slightly polish the gears and make them mesh better. Afterwards make sure you remove all the residue with water and or alcohol. You can also use an abrasive dental tooth paste instead of automobile rubbing compound. Make sure it's abrasive or else the only thing that you'll get is a car that smells good. In the case of the too tight a mesh you simply need to loosen it up.
3.) Some crown gears of some manufacturers do not work with other brands because the diameter of the pinion alignment trough is too great. This will cause binding and noise in the gear area. Unless you want to spend an hour sanding down the trough edges just replace the gear with one that fits.
4.) Finally, tightening up the slop in the gear / axle train will probably do more than anything else to reduce rear end noise so follow the procedures for that first and the rest of this may be unnecessary.
7. The Body Back To Indexa. Now let's take a look at the body. Many people think of performance only in terms of the chassis but there are a couple of points about the body which can improve overall performance. First and most important is rubbing of any moving part with the body. This usually happens with tires when there isn't enough clearance between the wheel assembly and the body and it can easily be corrected either by adjusting wheel/axle slop on the chassis or by shaving the offending body part with a Dremel tool or x-acto knife to gain clearance. This should only be done to under body areas such as overly large interiors or sloppy factory melt welding of parts such as headlight assemblies, etc.. Any modifying of outer body parts such as wheel wells is usually considered illegal at most organized races. Special note should be taken on front solid axle cars that when one wheel is pushed up into the body it does not bind with any body part. This can be one cause of de-slotting in corners; as the car leans the front wheel binds and off goes the car. This is a common problem with some of the older Scalextric Euro-sedans.(also see OBSERVATION Section.)
b. Any legal body weight reduction will improve your lap times because the Center of Gravity of the car will be lowered. If you want to see by approximately how much, try a few timed laps without the body. Check your track or club rules and take advantage of any weight reduction procedures allowed. This is one area where people like to cheat by shaving or edge drilling into parts such as interiors. Be careful that you stay legal. The best way to remove plastic from the inside of the body is to take a Dremel tool with grinding bit at low speed and slowly remove a layer at a time. One way to make sure you don't remove too much is to place a finger on the outside of the body where you are removing plastic from the inside. As you get close to the surface you will feel the heat / vibration. STOP at that point or you will grind through (and remove a layer of finger). Practice on a scrap piece of plastic to get the "feel" and you'll be surprised how easy it is to remove a sizable portion of the body weight. Experiment with different bits to find the ones that work best for you. I have found that a set of dental bits work quite well and may be cheaper than Dremel bits. Another area where weight can be saved is on the interior pod. Usually manufacturers mold quite a bit of extra plastic into the interior pod to allow other details such as fuel fillers, radiators, etc. to be attached as one assembly with the pod. You can save weight by removing these parts and attaching them separately and grinding away the excess plastic. You can also remove plastic that isn't seen like the floor under the drivers seat and plastic beyond the view through the cockpit windows. With careful plastic removal you can get a weight that approaches that of a thick vacuformed body.
c. If your rules permit some cars can benefit from lowering the body on the chassis. Car manufacturers will typically err to the high side on the cars height. This may be due to several reasons some of which have nothing to do with physical constraints. If a car can be lowered to look more realistic and also handle better go for it if your inspectors allow it. Usually shaving the mounting posts will do the job. However, on some cars with full chassis this lowering procedure may just be too hard to do expeditiously. Cars with body parts molded on the chassis will have to have these items removed first and glued to the body. This way there should be nothing inhibiting lowering the body by shaving the mounting posts. If you happen to cut too much off the posts never fear. Just take thin spacers / washers and shim it back up to the desired height. You can then glue them to the post and away you go.
d. Some racers advocate loosening body mount screws to increase performance. Well, on magnet cars with high down force, doing this may result in the chassis dragging on the track since more then a few plastic chassis cars use the body for chassis rigidity and loosening the mounting screws will allow the chassis to sag. On weaker magnet and non magnet cars there may be some merit to letting the body "float". I personally haven't noticed too much difference on plastic chassis cars with strong magnets and I think that this idea comes from the metal chassis / non magnet side of the hobby where it does make a difference. Try it. If it works for you, do it. Small soft plastic or rubber washers can also be used between the mounting posts and the chassis to partially isolate the body.
e. Just like gear noise, body noise is something that seems to plague some cars. Usually it can be isolated to one of a couple of causes.
1.) First, interference between the body and some moving part is a prime cause of body noise. Cars such as the SCX Ferrari 333 and Cadillac have almost no clearance between the body and crown gear. On many of these cars a raspy noise will signal that these 2 items are indeed rubbing together. The best cure is to carefully grind out the body area to gain clearance or shim the rear body posts ( least desirable because of CG considerations).
2.) On other cars the motor may be vibrating against the body shell or interior. Again the same solutions as previously mentioned should cure the problem. One other option is to take a small piece of sound deadening foam and fit it between the motor and body. This solution also works for some bodies that are just plain noisy because of their design. Sound deadening foam will greatly improve the situation and adds very little weight.
3.) Cracked mounting posts can allow the mounting screws to work loose allowing the body to vibrate. This can be fixed either by gluing the post and retaping the screw or putting a sleeve of plastic tubing over the post and gluing it in place to reinforce the screw hole.
4.) The last item which can cause body noise is loose bits such as headlight covers, window plastic and interiors not being securely glued. You can usually find these noise makers by shaking the body without the chassis installed. Gluing the offending part will fix the problem.
g. Although not exactly a body mod, taking advantage of the full track width of the body is important to getting the best cornering characteristics. Make sure that the tires extend out to the maximum track width allowed by your rules. A wider track car usually equals better cornering. Watch out if you are using replacement tires that are larger than stock because some car body interiors may cause interference. If it's not severe usually a little cutting on the interior tray will correct this problem. Also remember that tires expand to varying degrees with axle rpm. Tires that clear the body at rest may have serious body rubbing problems at speed. Gluing tires to wheels can reduce this problem in most cases.
At this point, If you are not doing Race Tuning you should run in
the chassis for about 50 laps or so stopping every 10 laps to check to
make sure everything is breaking in correctly. Check the motor temperature
as a hot motor could be a sign of excess drive train friction. Check for
uneven tire wear. This could be indicative of unbalanced wheel assemblies
or bent axles. Make sure the gears are meshing correctly and that the bushings
are not turning in their carriers. A roaring type sound at high speed may
indicate that the rear tires are expanding at high speed and that they
need to be glued to the wheels. Check that the brushes
are making proper contact with the track rails and that the guide is seated
properly in the slot with the front wheels just barely touching the track
surface. Check the OBSERVATION
SECTION of this article for other items to watch for. If
you observe any problems go back and redo that particular section again.
If you note a problem not identified in the first part of this article
check the other sections for possible solutions. If all else fails contact
this writer by e-mail describing the exact problem. We
will attempt to answer any inquires for information.
After this run in period you can still race tune the chassis. This
includes: magnet tuning and adding weight, choosing right gear ratios for
the right track, selecting rear tires for track conditions and upgrading
motors. These items are covered in
Section III of this
article.
A funny heading for slot car tuning, but this is one of the most important
tools you can employ to detect problems in your car's performance. Watch
the car as it goes around the track. Have your friends watch also. You
can't have too many eyes. What are you looking for? Basically symptoms
of any problem that might be slowing your car down or causing it to perform
below expectations. Here are a couple of the more important things to look
for other than those mentioned specifically in the General Section
of this article.
1. De-slotting: How does the car come off the track?
a. "Normal" de-slotting in a turn: The car spins out with the rear end departing first followed by the front end "twisting" the guide shoe out of the slot. This is what you should see when the car reaches it's rear traction limits if your car is balanced well, and all the general tuning tips have been followed correctly. If this happens at too low a speed for your satisfaction follow the Race Tuning Sections that deal with increasing rear down-force and traction. Usually this consists of magnet tuning for more down-force, adding weight towards the rear axle and/or upgrading the rear tires to a width/type that will give more grip. In rare cases you may even gain speed by going to a lower torque motor. This is because less torque translates into less drive to accelerate and break loose the rear tires.
b. Car suddenly flips out of the slot in a turn with both the front and rear departing nearly together. This is usually symptomatic of a car with too high a CG. It can be quite a violent departure when a high CG car has been magnet tuned without consideration being given to lowering the CG first. Your choices in this case are simple, either add more magnet to raise this limit higher (this won't fix the problem) or work toward lowering the CG , first by adding weight (Setting the Vertical Center of Gravity) and second by balancing it with magnets and tire selection (Race Tuning Section). Consideration should be given to also redoing steps 5b and 7b in the General Section of this article.
c. Car suddenly de-slots in a turn while decelerating and the car goes straight off with little or no sliding . This is usually caused by a variety of front end problems that cause the guide shoe to be driven out of the slot. The prime suspect is the edges of the front tires grabbing loading the front and pushing it up thus raising the guide. Tire rubbing is also a possibility. Recheck step 5b/c and 7b. Also check guide braid adjustment. Sometimes, a little up front weight helps but usually not in this specific case.
d. Car suddenly de-slots in a turn or on a straight while accelerating and the car goes straight off with little or no sliding. This is usually caused by the front end unloading and allowing the traction to push the guide shoe out of the slot. Add weight to the front end of the car behind the front wheels in 5 gram increments until problem is solved (usually less than 15 grams). If your rules allow adding a magnet just behind the guide will solve this problem also. The amount of magnet you use here can be critical because too little and you don't solve the problem; too much and you cause the car to lose speed. I usually start with a small magnet and drop more magnets to the top until the problem is solved or I reach the point of diminishing returns then I back off one magnet. Consider going to softer guide braids and insure they don't push the front end up too much.
e. Car begins to slide under acceleration out of a turn then suddenly de-slots possibly flipping the car. The car may also "fish tail" a couple of times before departure. This is usually caused by the cars rear tires transitioning from the plastic track to the metal rails and back to the plastic track as the car drifts. This affects short wheel base cars more than the longer ones and narrow track cars more than wide track ones. It is not usually a car problem but a deficiency in the overall design of the track system. Some brands of track are worse due to slightly higher raised power rails. If the problem only happens at a certain point on the track check to make sure the track is flat and that the rails are properly seated into the track. The problem can be helped by using stronger/wider traction magnets that have a wider field dispersal such as flat bars (Slotit type for example) as opposed to the cylindrical type. Adding weight can also help. This is because the wider magnet traction or weight will help to hold the rear down through this transition region. Also make very sure that the inside edges of your tires are properly rounded since these inside edges are the leading edges during rail transition. On some occasions different tire compounds will help also. Other than that, watch how and when you apply power coming out of the turn.
2. Power: Does the car appear to be getting proper power?
Normally a car should respond immediately to any controller input and the motor power should remain constant with a constant applied voltage. If the car does not respond in this manner and/or hesitates at certain parts of the track then something is wrong with the power circuit to the motor. For the purpose of this article we assume that you have a clean serviceable track. So the steps here are for the car part of the circuit.
a. Car slows down on parts of the track: If this happens and only to this one car than the problem most likely lies with the guide braid. Check that it is clean and serviceable. Consider using a soft thin competition variety. Now adjust it so that it makes proper contact with the track. The best way to verify this is to darken the room and drive the car slowly around the track. Any sparks observed means that one or both of the braids have momentarily lost contact with the power rails. This could still be a type of track problem so eliminate that first by cleaning and repairing as necessary. Readjust the braids and add a conditioner if necessary.
b. If all else fails replace the guide shoe as it may be excessively worn. If there is no sparking but the car still looses power, check the contact serviceability on cars that have sliding contacts such as Scalextric and newer SCX cars. On all others check that eyelets are securely installed and that all wires and solder joints are serviceable. Recheck General Section Procedures 2b&c and 3e. Euro cars are notorious for having sloppy guides. If you can't seem to get the braids to consistently make good contact you might want to consider reworking the guide and guide holder (General Section 2d) to tighten it up. This should help solve any nagging braid contact problems.
c. Though not directly related to power application, one other possible cause of the symptom described is a traction magnet intermittently shorting out to the track at one or more points around the track. As it shorts, it sucks down the power and slows the car. This type of failure is critical because it can cause a controller or the track connections to melt and become unserviceable. If you suspect this problem paint the bottom of the magnets on the car and run it around the track. Carefully inspect the track for evidence of the paint and repair that area as required or raise the magnet. One other symptom of this type of problem is the controller becoming excessively warm after running the car a short time. You may also observe sparks coming from under the car as the magnet shorts out.
d. If you've done all this and still have the problem then change out the motor and see if that fixes the problem. If so, then there is a problem in the motor, which is presently beyond the scope of this article. Sometimes loss of power comes from either a cold solder joint or a wire/solder joint that is about to break. Check the wire to motor connections very carefully if you are having this type of problem and reheat the joints with a soldering iron if there's any doubt about the joint's serviceability. Problems usually occur when the wires are allowed to flex at the motor connection. Placing a piece of tape on the wires to hold them to the chassis will greatly reduce the possibility of this problem happening to your car. Spending a little money for good flexible lead wire can also save you from having these problems in the future.
3. Car slows noticeably through tight turns
a. Sometimes a car will seem to slow down and "drag" through tight turns. This can be caused by several factors. The first thing you should do is take the car and run it by hand through the turn and observe and "feel" what the car does. If it drags here you may be able to determine the exact cause and correct it.
b. The first and most common problem may be that the front wheels are dragging through the turn, in which case, the front end needs to be worked per the general instructions to lower front wheel friction.
c. Another cause may be that the rear magnetism is too strong along the center/forward/aft axis and is causing the guide to drag because the rear is not allowed to track through the turn properly. The best solution here is to either lower the center magnetic traction by going to a multi-magnet setup or move the existing magnet forward slightly to decrease the magnet to guide distance. This is quite a complex problem because you must find the best solution that balances the car for the whole track. A small change to correct a deficiency in one turn may create a whole new set of problems at other points on the track.
d. One other possibility is that the guide shoe is too long, front to back, and is binding in the slot. This is common to Carrera cars used on tracks with tight turns. The easy solution is to remove a millimeter or so off the rear of the guide.
e. Finally, If you are running any magnets close to the front axle you may be picking up flux line friction from those magnets. Many people slap magnets on the car near the guide and front axle assembly and fail to realize that the front axle is ferric metal in most cases and will be effected by close proximity of magnetic fields. The best solution if you think this could be a problem is to go to a non ferric axle, either plastic or aluminum / brass. I like brass or aluminum thin wall tubing because it's light and strong.
a. What if the car appears to slow on the straights? Well, this is uncommon in most cases but there are a couple of things to look at if you have a problem like this.
b. First, If the car initially accelerates okay and then seems to bog down you may be seeing the effect of rear tires expanding and either vibrating or rubbing the body. Usually you will notice a " whooshing" type sound but not always. What you need to do is go back and glue the rear tires to the wheels and this should solve your problem. Also check that you haven't bent an axle because this will also give to a similar symptom.
c. Next, If your car seems to get up to a certain speed and just kind of runs out of juice you may need to do some gear ratio work. Different tracks may call for different gears and sometimes even a slightly longer straight section may dictate a change in gearing.
d. Finally, if your car is slow to accelerate you may be suffering from one or more of several problems. First check for lubrication and check that nothing is obviously binding. Check that the front wheels are turninmg freely. See if the motor is getting excessively hot. This may indicate either binding somewhere in the drive train or that your running too much downforce for the motor type. One last thing may again be gearing. Check that you've got the right ratios for the type of track your running on.
a. Car noise needs to be isolated to the offending parts before a good solution can be found. What should be done first is to figure out if it's a chassis, body, or chassis to body problem. Running the car without the body should quickly identify this fact.
b. Chassis without the body should be pretty quiet so any racket without the body is either gear, bushing ( both axle and pinion shaft; as applicable), motor/mount, gear mesh, front guide or front axle assembly. Removing the front wheel assemblies) and running the chassis will eliminate or identify this area as the problem. Rear axle and pinion shaft bearings should be glued into their carriers. All slop should be removed from the rear axle assembly by using washers/spacers as required. Motor and motor mounts where applicable should be glued in; I like RTV because it is a vibration suppressant and can be removed easily if a motor change is required. Guide slop can be corrected per the info in the General Section. Gear noise can be corrected or reduced after axle shimming by putting a dab of paint rubbing compound onto the gears and running them at low speed for a couple of minutes, stopping periodically to work the compound back into the gears. This should be cleaned thoroughly afterwards with water and alcohol.
c. On the body first take it and shake it thoroughly to see if any parts are loose (See Body section). Prime offenders on FLY cars are the headlight assemblies which are hot melt mounted and sometimes the weld is not good. Super glue will quickly fix this problem or any other loose parts problem. Be careful to use the glue sparingly because it has a tendency to run and you don't want to mess up that beautiful paint finish with it.
d. Finally put the chassis and body back together and check for any interference between the gears, motor or wheels/tires and the body. any interference can be corrected either by shims or by grinding away part of the body underside that is causing the problem. With all that done your car should be nice and quiet. If it isn't than the last thing you can do is add some sound deadening foam between the body and motor (just a small piece should do it) to isolate the motor from the body.
a. This is probably one of the scariest things that can happen to you . You are driving your car around and suddenly you see and smell the signs of electrical smoke coming from your favorite car as it stutters to a halt. What should you do?
b. First, shut down the power to be safe. Now, figure out what caused the problem. Several things can cause the described symptoms most of which aren't terminal. The most common failure in a car in this situation is that one of the EMI filter Capacitors or inductors has gone "high order" and self destructed. This is quit common on tracks running over 14vdc. Some of the small devices used on the outside of the motors just can't handle the extra voltage that some of the power supplies put out. Removing these components before it happens will save the adrenaline rush of seeing your toy smoking.
c. A second cause of smoke is over lubricating the motor bearings, allowing the excess oil to get on the motor commutator. Short of taking the motor apart to clean the comutator the only thing you can do is to try soaking the comutator end of the motor in alcohol or lighter fluid to break the oil down. Re-lube the bearing and try again. You may have performance problems until all the residue is "burned off" by the motor brushes. See there's a reason people tell you not to over lube the motor bearings.
d. The third likely cause is a strand of one of the contact braids becoming shorted across the rails. This seldom happens but on Carrera guides it may be more common because of the way it's built and the type of braid used. Removing the offending strand will cure the problem.
e. The fourth likely cause is a motor lead wire that is about to stress break becoming resistive and overheating. This usually happens at the motor connection and can be spotted by looking for broken strands at the solder joint. Stripping and re- soldering the wire will fix this. Taping the wires to the chassis so that they cannot flex at the motor joint will prevent this from happening again.
f. The last and most terminal cause of this problem is a motor that has "given up the ghost". Short of rebuilding the motor which is usually not very practical for this level of motor, replacement is the only solution. Before you do replace the motor; however, you may want to investigate whether there was something such as too much magna traction which caused the failure. You don't want to lose another motor for the same reason.
g. The causes we've identified here are strictly failures in the car. Other track and controller problems can cause electrical failures of the type described. These items are presently beyond the scope of this article. One item though worth mentioning is what happens if you short out the track rails with a traction magnet or similar. Usually the car will stop and if you continue to hold power on the controller something is going to give. This is usually the controller or the track wiring or sometimes the power supply itself. So be careful when running traction magnet
s and consider fusing your controllers or power supply as a safety action.7. Other observations: Redo applicable General Section procedures related to the problem.
Race Tuning consists of eight general areas; Setting the Center of Gravity, Magnet Tuning, Weight Tuning, Selecting Gear Ratios, Motor Selection, Tire Selection, Optional: Chassis Weight Reduction and Guide Shoe Modification, and Putting It All Together. There is no particular order which should be followed except that "Setting the Center of Gravity" should be done first. All other sections are interrelated and need to be done in close conjunction with each other but, do not try to accomplish everything at once or else you may lose track of what's what. Get the most out of one area first then go to the next and so on. Then go back and see if you can improve each some more. Continue this way until you get what you are looking for in the way of performance.
1. Setting the Vertical Center of Gravity (CG)
a. The first thing you should do when Race Tuning is to get the vertical CG of the car set as low as practical. This can be done using weight at or below the axle line and by lowering the body mass. An ideal CG has over 50% of the cars weight below this axle line. For many cars out of the box this is not the case. Eurosedans, in particular, are plagued by a high CG and narrow track; a bad combination for good handling.
b. You can get a rough estimate in most cases of what your cars vertical CG is by first weighing the complete body assembly, and the complete chassis assembly without the motor and wheel/axle assemblies. Next subtract 3/4ths the body assembly weight (in grams) from the chassis assembly weight (in grams). If the number is positive then you are in pretty good shape. If it is negative then you should add weight below the axle line until the number becomes positive then add +10 grams for every cm of body height greater than the car track width. This weight should be applied somewhere below and between the front and back axles at a place determined by, and using the procedures in, the Weight Tuning Section. Remember, in general, the more positive this weight number is the more predictable your cars handling characteristics should be.
c. It is critical that the vertical CG be set before any other Race Tuning procedure is accomplished or else unsatisfactory tuning results will almost certainly be obtained.
2. Magnet Tuning Back To Index
Let's begin with some general information:
First, the further forward a magnet is mounted toward the guide shoe in a chassis the more drifting a car will do in the turns and the less the down force applied to the rear axle. The further aft you mount the magnet toward the rear axle the less sliding you get in the turns and the more the down force applied to the rear axle.
Second, the optimum magnet position should be chosen carefully taking into consideration what you are trying to achieve, maximum lap speed tuning or performance matched tuning (PMT) with other similar class cars.
Third, magnet tuning is three dimensional. Moving magnets in any axis will affect the handling so keep aware of these changes when tuning your car. If you want to compare relative downforce between cars statically, you can get a rough comparison by using a spring scale graduated in units of weight. A digital one with max hold feature is best, but a simple weighing scale can be used effectively. By measuring the vertical pull resistance at the rear axle while the car is straight on the track you can obtain the downforce being applied when the car is on a straight. By measuring the vertical pull at the rear axle while the is placed at various angles off the center line you can see how much downforce is being applied as the rear end as the car transitions off center to a slide. By attaching the scale to one side and pulling horizontal at the rear axle you can measure the sliding friction which is a combination of magnet / weight downforce and tire grip. All this information will help you in setting the downforce which best suits your purpose. Don't forget also that when measuring track clearance on a magnet car use an actual track piece if possible because the magnets cause the tires to flatten slightly so that on a non-metal surface the clearance will be higher than on an actual metal rail track.
One last point to consider when magnet tuning your car is differences in track power between where you tune your car and where you race it. If it's the same track then no problem; however, if it isn't you should try to magnet tune at the same or as close to the same race track power as you can. This is because the effects of magnet traction vary greatly with speed. So what you set up for at 12vdc/3amp may be totally wrong for a track at say 15vdc/3amp and vice versa.
a.Maximum Lap Speed Tuning: This is usually easier to set up because the magnet location will be just forward of the rear axle on most cars. If the magnet cannot be mounted there, then a stronger magnet shifted slightly forward is the next best choice. So how about the cars that have inline drive train with no space provided to mount a magnet within even 4 cm of the optimum location? Well, my solution is to glue a thin (< 2mm) neo-type magnet right to the bottom of the motor at the pinion end. Does it work? You bet! So how do you tune it? If it's too low, put larger tires on the back wheels or find a thinner magnet. If it's too high, shim it down, use smaller tires, or a thicker magnet. That simple. On Fly sidewinder cars with a hotter motor than stock, a good magnet mod is to remove the original magnet and install a Slotit bar magnet to the bottom of the motor. You will have to remove some chassis plastic but this is about the best position for a single magnet configuration on this type of car. It is also a good starting point for multi-magnet configurations.
b.Performance Matched Tuning: If you decide that matched performance is what you are after then that's a little more difficult. Sometimes magnets alone cannot accomplish this to your satisfaction so this advice should be considered along with tire, motor, and gear ratio selection and weight application since these are variable factors as well in changing a cars performance. These subjects are also covered in this article. So where do you start? Well, is the car you are tuning faster or slower than the cars you are trying to PMT to? Faster read on; slower read on anyway.
1) Faster car than the cars you want to PMT to:
a) If your car is faster, usually the first method of slowing it down is to raise the existing magnet further away from the track. If the car has a magnet pocket, placing thin pieces of paper/plastic (I use pieces of plastic coated playing cards) between the magnet and the chassis will do the trick. Add a piece run a couple of timed laps and repeat until desired time is achieved.. Remember, elementary physics states that the magnetic field of a magnet is approximately proportional to the inverse cube of the distance from the magnet. Therefore, if you double the distance from the magnet, the magnetic field strength will be reduced (roughly) by a factor of 8. So a little raising reduces the down force by a lot.
b) If raising the magnet isn't possible or feasible then the next best option is probably to replace the original magnet with a smaller one. Magnets come in all shape and sizes and are relatively cheap so you can stock a varied supply. Choose the common shapes (cylinder, flat bar ,etc.) in various thickness' (thickness usually equates to strength on small neo-type magnets). I like these or similar Ninco 70223 (8x2), I.M.A. (Spain) #INED0009 (8x3), 70179(8x5), 70229(3x6), 70157 (13x8x3); Wondermagnet #9(3/8x1/16), #10 (6mm); Where do you find them? At your local hobby/electronics store or on the net are the best places. Internet stores can help you out and I've had good luck with (www.wondermagnet.com). Remember stacking magnets essentially add their individual strengths together, so you can simply drop one magnet on top of another to increase the track down force. With this in mind start with a magnet about 1/2 the strength of the original and add 1/8 or so strength magnets between timed runs until you get the times you are looking for.
c) If you still can't get it quite right read on. The next best option is to shift the original magnet forward toward the guide shoe. As you get further away from the rear axle the amount of rear down force will decrease allowing the car to drift more in the turns and in most cases ultimately if moved further front will allow the rears wheels to spin due to loss of traction. The result then of moving the magnet forward is an increase in lap times. Light to moderate amounts of magnet strength at the center or towards the front will tend to give your car handling similar to that of some of the "classic" makes from the sixties. Cars will drive with controlled drifts and will not have that "stuck down" feel.
d) The fourth magnet option to slow the car down is to remove the original magnet and to use multiple smaller magnets at different points on the chassis to get a desired handling effect. Start with a small base magnet reference (again toward the front if you want drift; toward the rear axle for less drift more rear traction) now you can add small magnets forward or aft, left or right of the base magnet to get desired handling/timing results.
2)The car is slower than the cars you want to PMT to:
a) You use essentially the same methods as for faster cars. In the first method instead of raising the magnet you will want to lower it. This is usually done by opening up a hole in the chassis under the magnet well so that the magnet can be pushed closer to the track. Secure it with super glue once you've established the distance and away you go. If you go with this method you might want to go a step further and make the magnet adjustable. On round magnet cars, I've had good success using short aluminum screw posts with flat screws that are used in document binders. I glue the magnet to the screw head and mount the post on top of the magnet well. Then I can simply screw the magnet up into the well from the bottom of the chassis. I use a drop of rubber cement in the well to give an interference fit and cut a slot in the thread end of the screw so that it can be adjusted with a jeweler's screwdriver from the top of the chassis sitting on the track. A drop of glue or nail polish can be put on the bottom of the magnet will keep it from turning from vibration.
b) In method 2 instead of replacing the original magnet with a smaller one; go to a larger one or better still just add a second to the top of the first. You don't have to glue it or remove the plastic in between. The 2 magnets add their force together (minus a small amount). You can vary the amount of down force by experimenting with different strength magnets. Just pull one off and drop another size on. Like I said you don't have to glue them on. I've used this method many times (one of my Fly Porsche 917s comes to mind) and have yet to have one come loose in a crash.
c) In method 3 shift the magnet towards the rear axle if possible. Better still, consider getting rid of the original magnet and gluing a thin magnet to the bottom of the motor (inline drive) if there is adequate clearance.
d) Method 4 is essentially the same for PMT slower cars except use larger magnets. I use this method when I have a car that I want to drift but at a higher speed than with the original or no magnet. The addition of a small flat bar magnet just forward of the rear axle in addition to a forward mounted stronger magnet will give this affect on some narrow tired cars that originally had no magnet such as Pink Kar's Ferrari GTO and Ninco's Classic Series cars. This method is also the best way to get the most performance out of your car. Strong magnets mounted just forward of the rear axle, toward the outside of the chassis will give you more downforce as the car begins to slide. A weaker magnet either under the pinion gear or just in front of the motor will give you the weaker downforce for straight line traction. Combinations of magnets using variable strengths can help you to tune your car for individual track configurations much as real race cars are tuned to each track. Don't forget magnet tuning is three dimensional up - down for magnetic attraction; in - out - forward - back for balance and handling characteristics. I find that a cheap spring scale can greatly assist you when trying to set up multiple magnet configurations. You can use it to pull your car or chassis sideways by the rear wheel and take measurements as each magnet or magnet set passes across the contact rails. Careful manipulation of magnets can allow you to set up smooth departure transitions for more controllable slide departures and also allow you to set up strong downforce at extreme angle configurations that doesn't adversely affect straight line speed. Also, don't ignore the front end completely. Magnets just behind the guide act to hold the front end down in tight turns and to stabilize sideways movement. Magnet strengths in this area are usually less than at the rear where magnets are used mainly for traction. What I usually do is glue a small value magnet behind the guide, run laps and drop on more magnet until I reach the point of no more time improvement. Then I remove one magnet and use half of it strength value and retest. Eventually I get the optimum value of forward downforce. You may have to play with the back magnet a little to get the exact rear setting after you've set the front. Finally, if you want to increase the downforce slightly of a particular magnet or magnet set you can use thin ferric sheet metal shims on the opposite side of the magnet location to where you want to increase downforce. These ferric shims don't increase the field strength as many people will try to tell you but "squeezes" and redirects the field so that the flux lines are directed slightly off their normal pattern, increasing their density in the area opposite from the shim . You can also use ferric metal shims to "block" flux lines from interfering with steel axles or other ferric components. By placing thin spacers vertically to the magnets you can also set up magnetic boundaries in your traction fields. This can sometimes be beneficial to improving straight line speed. If you want to see exactly what I'm talking about take a magnet and put a small piece if sheet metal on one side now observe the difference in magnetic attraction between the side with the metal and the side without. Remove the metal and see that the magnet side opposite the metal had a greater perceived attraction than it does without the metal on the opposite side. There are some interesting possibilities in using this principle for magnet traction.
As you begin to become familiar with these methods of magnet tuning, you will come to realize that not only can you PMT for speed but you can also change handling characteristics as well. Anything from Stuck down like a train on rails to sliding and spinning all over the place is available; you choose. Though beyond the scope of this article you can also experiment with opposed force (like-poles forced close together) magnet mounting and magnetic field directing using ferric metal shims. These let you direct magnetic down force so that on the straights it is minimal for greater speed and in the turns increases with drift off centerline for greater traction. Check you race rules before using multiple magnets since some rules forbid their use.
3. Weight Tuning Back To Index
On low/no magnet down force cars where magnet tuning is either not desirable or allowed by your rules, adding weight (weight tuning) is the best way to gain traction and cornering speed. A good rule of thumb is to keep it as low as possible in the chassis so the car's center of gravity remains low. How much weight needed and where to put it are determined by several factors:a. How much weight is needed? Motor torque pretty much dictates what the maximum amount of weight a car can carry is and still remain competitive. The more torque available the more weight that can be added without bogging the car down or adversely affecting braking and acceleration. This is where the Lead Sled advocates put their money. If the car is well balanced though then heavy or light is pretty much a matter of driver taste although heavier seems to be the current trend.
b. What do I use? Lead tape, lead sheets, lead wheel balance weights, lead fishing weights, lead or any other metal is okay. Lead because of its weight per volume and softness is usually preferred, but brass, bronze or iron is also used probably for ecological / esthetic reasons or for their soldering properties. When I add weight I usually use lead tape and wheel weights because the adhesive is already applied so I don't have to mess with glue. If you have the tools you can also make your weights out of brass sheet metal by cutting pieces to form fit. This method has the advantage of allowing you to make a belly pan for your car and with mounting screws or glue, attaching it to internal brass balance weights. You can get an idea of this method by looking at the example drawing in the drawing section.
c. Where to put it? It's similar to magnet tuning a car. If you are trying to increase traction then add weight over or near the rear axle. If you need to hold the guide shoe down under acceleration or want controlled drift mount weight further forward toward the front axle. It's usually a good idea to avoid putting too much weight aft of the rear axle because if the CG of the car is too far aft, then normal car drifting in the turns quickly translates into an uncontrollable spin out. Weight applied to shift the CG forward should be applied carefully in 5-10 gram increments so that the minimum amount to accomplish the job is found. Lead tape comes in different thickness' and can easily be applied to the under side of the chassis if there is clearance and rules permit. This allows easy balancing of the car without removing the body. Once the proper weight has been determined I usually put a little spray paint on it so I can see if there is any bottoming of the car around the track. If there is, I can find out if it's a track problem by finding where the scraped off paint is on the track and investigating why it happened. Sometimes when trying to balance a car with weight you end up adding too much weight because you added weight instead of moving the weight around. Always try shifting a smaller amount of weight to see if it corrects your handling problem before adding more weight.
d. When do you use weight and when do you use magnets? Well what do your rules allow? I will always use magnets over weight because there is less moving mass. This usually translates into less damage in accidents if the speed of the cars is the same. Don't over magnet a car unless you are prepared for sudden departures that you will not be able to react to in time to stop a heavy hit. This often happens when tuning for maximum performance. I use small amounts of weight to shift CG slightly in a car so that the guide doesn't float or use weight when rules prevent the use of multiple magnets and I need more car balance. One important point is that weight should always be used when trying to lower CG. If you try to control high CG characteristics using magnets you will not like the results as the car will be virtually impossible to control at the traction limits and will depart violently when these limits are exceeded (see Observations Section). By using weight first to lower the CG you will obtain a much smoother transition to drift, which you can then tune using magnets. Some people argue that magnets make the car less fun to drive. My answer to those people is that, when used to PMT cars they actually improve the fun factor. Magnets can also be used to increase the speed of a novice driver (sort of like PMTing of the driver) so that he or she can give a good account of themselves in a race against a more seasoned pro. Nothing is more disconcerting to a new comer to this hobby than to be continually wiped up by others in every race. Using magnets to equalize drivers can keep this from happening all the time. As the new driver's skill increases he can graduate to cars requiring more or varied skills. There are many who disagree with this line of thinking so you will probably hear arguments to the contrary. You choose what you like.
e. There is one final point that I will add here and that has to do with a well known "secret" that some of the metal chassis boys have been using for years; shiftable weight. The principle here is to put a small amount of weight on a chassis in such a way that it shifts to the rear under acceleration giving traction and shifts toward the front under deceleration to give guide stability through the turns. The amounts of this shifting weight are modest due to other factors involved but the principle does have some merit. So how does the poor plastic chassis guy do this? Well the best way is to take a piece of 1/16" brass tubing and mount it cross wise in the chassis between the motor and the guide. Usually mounting it through chassis uprights is the best method. Next take some brass sheeting and cut a couple of small pieces to fit in the side pods of your chassis if it has them. Make them short enough so that they can pivot about the tubing in both forward and aft directions. Now attach the piece of brass tubing to one end of the strips so that you have an axle with piece of brass hanging off at each end. This should be mounted in such a way that it acts like a pendulum if the chassis is held upside down. the brass should be free to move in a 180 degree arc forward and back. If this is done right, when the chassis accelerates the brass weight will pivot aft; on braking it will pivot forward. You can try it on an old chassis to test the principle if you want to. There are other ideas for shifting weight which you can experiment with such as the sliding bar weight which is essentially a brass weight on brass tubing that slides along each side of the chassis on piano wire with small spring at each end to cushion the movement. You can put this mod on a fly chassis for example without too much trouble. Usually, high magnet downforce cars won't be overly effected by this type of modification so it's worth on such cars is probably negligible.
4. Selecting Gear Ratios
a. I'm no Pro in this area but a good general rule is that on large tracks with wide sweeping turns gear ratios of 2-3.5 to 1 are usually good. On smaller twisty tracks 3.5-5 to 1 usually works best. (There's a decent chart for ratios at Slotit's site www.slot.it/eng-proaxle.html). Also tire diameter plays a role in the actual ratio obtained (See Tire Section). Another factor to consider is the type of motor you are using. The more torque it has, the lower the ratio that can be used without causing the motor to bog down coming out of the turns. ( i.e. a higher torque motor could operate on a 2 to 1 ratio whereas a lesser torque motor would have to run at 3 to 1 to maintain speed). Also the higher the torque rating of the motor the more motor braking action the car will have. (i.e. to get the same stopping performance that a high torque motor gets with 2:1 gearing, a lower torque motor might have to run 3:1 gearing. Motors like the NC2, Slotit Boxer, and Cartrix PRO have more torque than say the standard Scalex/FLY motor so they could give the same braking even though they have a ratio that was lower. Thus an NC2 at about 15-18000 rpm (depending on the voltage) with more torque can stay with and beat a 19-22000 rpm motor like the Scalextric (given equal tire size) because the higher torque factor in acceleration and braking allows lower gearing. Some of the "newer" motors have combined and traded off certain factors to try to give us the best of both worlds. Slotit and Plafit and Cartrix to name a few have tightened the manufacturing tolerances of their motors which allows hotter winds and stronger motor magnets without adversely effecting motor life to a great extent.
b. You will have to set up your ratios so that on your longest straight the motor is reaching its top rpm just after 3/4 way then maximum brake and power into and through the turn. I find that on my track this means that I could go with lower ratio gearing on the NC2 fitted cars and higher on the Scalextrics and FLYs. If your track has a lot of tight turns and short straights; however, you might find that keeping the motors at higher rpms by using higher ratios brings you more overall lap speed.
c. One other thing to consider when gear tuning is track power. Most motors have a voltage range that they are designed to work at. Below that range the torque drops off significantly. Above that range the motor gets "torquey" and difficult to control over a range of speeds. Different tracks operate at different voltages usually between 12 and 18vdc. Gearing set up for one voltage may not work at another one so watch this variable. Gearing combines with motor torque, track voltage and controller ohm rating to give you controllability over a range of speeds.
d. I know this all sounds very confusing so let me give you the simple way to set up your car for a particular track.
1) Take the car/chassis that you want to tune and set up several axles with different size (24 27 30 for example for inline motors) gears and use an 8 tooth pinion for a short track or a 10 tooth pinion for a longer track (inline motors).
2) Run each axle combo for around 10 laps and take the times. Also observe controllability with each combo.
3) Next install a 9 or if you have a big track 11 tooth pinion and repeat test. After you do this you should have a fairly good idea of which ratios run fastest with which motors. Play with these combos until you are happy with the lap times and driving characteristics of the car. For inline motors, Slotit's new gears and axles along with their pinions should provide all the ratio combos you could possibly need. They are also quick change so you only need one axle in the above procedure.
4) Once you determine the best ratios using the Slotit set you can always go back to standard plastic gears of the same tooth count on standard axle assemblies if you so desire.
5) For the sidewinder drive such as FLYs and Proslots you can use the Slotit pinion set and even the new spurs if the pinions don't give you enough ratios. Procedures are the same as those for inline drives.
6) After you setup gearing for one car, other cars with similar motor / drive trains/ tire size should use about the same ratios. You can fine tune gearing for these cars with the similar drive trains, but this usually isn't necessary at my level of racing because weight and magnet adjustments make bigger differences in performance after choosing the best general gear ratio using this procedure.
5. Motor Selection Back To Index
Motors come in many and varied performance levels. The motor you select should be broken in according to manufacturer's recommendations. Running the motor at 6 volts for 20 minutes or so usually works to seat the brushes in absence of factory procedures. If you are in doubt, contact a tech site for recommendations. If you choose to upgrade from a stock motor you should consider the following motor parameters:
a. Motor rpm range: This in combination with gear ratio generally determines top speed; magnet down force, weight and tire size are also factors. Go for the most rpms on large tracks with sweeping turns and medium downforce magnet configurations. Control with rear end gearing.
b. Motor torque curve from stall to maximum: This in combination with gear ratio generally determines acceleration to top speed. Torque is also instrumental in determining how much magnet down force can be used without overly bogging down the motor and causing overheating. Finally, torque is a determining factor in how much dynamic braking a car will possess. Go with max torque over rpms on tight twisty tracks and high downforce configurations. Again control with rear end gearing. Don't forget that traction magnets supplement motor braking and may eliminate the need for it on high downforce configurations.
c. Motor size and shape: Not all motors fit all cars. There are many adapters though so don't just settle for common swaps. For example, any NC2 type motor, using Reprotec RT-10 or Cartrix motor brackets and long pinion will fit any SCX RX-4/6/8/PRO powered car (the shaft may be a little short for the gear self align feature so washers/spacers might have to be used to set up the gear mesh properly) . What does this mean? How about a Slotit boxer motor powered Ferrari 333SP. This would undoubtedly be one the best/easiest SCX car power upgrades presently available, in my opinion, and it just snaps in then a little axle shimming and off you go. Another example, Cartrix motor sets come with a Cartrix Cheetah type motor and Ninco mount for cars with removable motor adapters. How about a Cheetah type motor in the old McLaren GTR for a performance boost. The list goes on and on. Some of these adapters are listed Motors / Adaptors Chart in this article. This is by no means the extent of the replacement possibilities. New manufacturers and dealers are showing up every month. So check with your slot car sources regularly to get the latest and greatest motor/adapter upgrade availability. The only downside to all this is that many of the adaptors are only available with other motors so to get the adaptor you want you may end up with an extra motor. Once you get an adaptor it's relatively easy to make replacements using casting resin.
d. Motor power consumption: Make sure that the track you are running on will be able to handle the hotter motor. This is usually not a problem except with some of the weaker stock power supplies. One way of checking to see if you power is adequate to handle the motor or motors you are running is to take an volt meter (preferably an analog type) and put it across the power supplies positive and return. Watch the meter carefully as you run your cars. If the voltage dips at all then the supply is not giving all the power that the motors are asking for. If this is the case then you should consider upgrading your power supply. Most wall supplies will show fluctuations and need to be supplemented by a second unit if you want satisfactory power operation. Small amounts of meter fulctuation on these wall supplies are normal since they are unregulated and will vary with the load. When measuring these units to see if they are adequate for your motor you need to establish a reference voltage you want to run at. If the meter drops below that voltage at any time while running your cars then the supply is not adequate. If you intend to run mulitple cars on one supply it is better to use a regulated unit of adequate output so that each car will get the voltage it requires. If you are in doubt your dealer should be able to help, or check a tech support Internet site. Also don't forget that most stock controllers and track connections aren't built for high current (greater than about 1.5 amps). If you are going to be running motors hotter than say the Slotit motors or high magnet downforce configurations then you should consider going to better controllers that can handle the increased power requirements. Parma controllers are good cost effective upgrades to consider.
Some track systems such as Ninco have printed circuit boards as part of the power interface. These boards can be destroyed by too much current. So if you plan to use more than the manufacturer's recommended amount of power you will need to rewire this interface and eliminate the circuit board.e. Track Power: This is a very important consideration in motor selection since some motors are designed to run better at 12vdc while others are more efficient at 14.5+ vdc. Motors such as the Cartrix, Slotit V12, and Plafit Fox/Cheetah types work well at both extremes but others such as the RX series seem to do better at the higher voltage.
f. Controller used: For most of us, the controller we use is dependent on the motor's characteristics and car configuration. There are times; however, when the situation may be reversed such as a race where the controller type and ohm rating are specified in the race rules. In this situation you must be careful that you choose a motor that performs to your expectations using that particular controller. If you are doing the driving this can be a relatively painless task but if it's for a proxy type race the motor decision could be a bit more difficult. In a future update we will approach this problem in more detail and offer some solutions that may assist you in choosing the right combination for this type of race.
g. One last thing to consider is motor life. The higher the performance of the motor and lower the quality the shorter the motor's life. All things wear out so don't be surprised when your motor begins to lose some of it's pep. Most motors for Eurocars will give you hours and hours of enjoyment if they are taken care of. Cheetah motors with their higher rpms tend to slow down after one or two good competitions. Since brush replacement isn't usually considered an option with these motors the best thing to do is retire them or use them on less demanding cars. You can rework these motors if you want to try but economics usually dictates replacement.
6. Tire Selection Back To Index
Rear tire selection is most important for low and medium down force cars as well as for determining overall rear end ratios and depends mainly on:
a. Track surface. For the purposes of this article I am using my experience with Ninco plastic track only. It is generally recognized in race circles that Silicone tires rule the plastic track. This may be true on smooth clean surfaces but may not follow on rougher surfaces such as Ninco style track. Silicone tires offer no performance increase over rubber on Ninco track, particularly on high downforce cars. What is said about contact area and traction is essentially true and is proven by the fact that treaded tires do work better on the rougher Ninco track. If you take a magnifying glass and strong light and look at the tire to track surface interface on treaded tires you'll notice that the treaded tire develops "fuzzy" ridges that fit down into the rough surface allowing more contact than silicone because the silicone compound tire won't do this but will tend to "chunk" instead, so the silicone tire will basically sit on top of a bunch of small peaks not making near the contact of the treaded tire on Ninco track. Rubber slicks develop the same fuzziness but it appears to be slightly less than the treaded tires so for the most part the treaded is a better overall tire to the rubber slick also. Over time the track surface acts like many small razors cutting the tread to create this "fuzziness". If you are using silicone what this does is create cuts which eventually expand and cause the tire to disintegrate. During our tests for both the Mania and the Memorial race we experienced silicone tire failure after about 300 laps on a tight turn circuit using high downforce cars. What appeared to happen was that the edges of the tires would get these small cuts and this would cause them to start to separate. For this reason we were unable to verify the silicones reputed superiority on smooth track because we destroyed all our examples. Remember Ninco track is so abrasive that you can actually "sand down" your tires with the track if you hold the car down in a stationary position (DON'T do this or you'll make the track smooth at that point by melting the plastic). If you look at most of the competition tires offered by Spanish vendors for Ninco track you will find that most are treaded. Reprotec has a large line of competition tires. These tires are generally meant to replace Scalextric / SCX tires on Ninco track to give better traction (three P/N's are AS12301/8/9). Below is a quick chart on lap times for 2 particular cars using different tires. Perhaps it will be of assistance to those of you with Ninco track.
CAR STOCK TIRE- INDYGRIPS SILICONE- AS2309- NINCOTREADED
Ferrari 333 2.91sec 3.08sec 2.81sec 2.83sec
w/Cheetah and
Slotit magnetNinco McLaren
w/Cartrix Pro See Ninco
Set Treaded 3.30sec 3.19sec 3.18secI've found that tires such as Ninco soft treaded and slicks, Fly slicks and classics, MRRC classics and Cartrix slicks work well on Ninco track. Most SCX and Scalextric tires are slightly harder compounds and can be used where a certain amount of drift is desired. Some of the newer SCX and Scalextric tires are softer; however, and are good all around tires. Reprotec has a series of tires that have a Silicone component that work very well on Ninco and Scalex/SCX track and are quite durable. In general, the softer the tire the greater the traction.
b. Tread configuration: You could probably write a book on this subject alone. Whether to select a tread pattern or slicks usually goes back to track surface again. On rougher surfaces, treaded patterns do seem to work quite well with all types of cars from non magnet to maximum down-force types. Slicks are better on the smoother varieties of track. If you are using treaded tires and your car is digging in and flipping in the turns even after you've rounded the edges then consider going to a slick tire or sand off some of the tread pattern on the tire.
c. Car type and configuration: Wider tires of a certain compound generally give more traction then narrow ones and help to cure CG problems on narrow track cars that are top heavy. Go with the widest possible rear tires that 1. Meet your realism requirements 2. Meet the rules, and 3. Fit under the car. Also be aware that some tires degrade with time much faster than other brands. This may be due to several factors but most often certain chemicals can have a detrimental effect on the tire compound. Be careful with lubricants as some of these may break down certain tire compounds resulting in overly soft or hard tires that lose traction. Further, watch out that you don't heat the tires up too much as this can have the same result. Under most conditions this is not a problem but particularly when sanding the tires be careful not to apply too much force as this will definitely cause the tires to overheat and may damage them; especially if they are silicone type compounds. Below are some typical configurations that I use on some of my cars. Remember I have Ninco track so silicones are not much help. They are by no means meant to be the best combinations. They are just what I use that give me a cost performance ratio I'm happy with.
1) For narrow tire classic cars such as Pink Kar's Ferrari GTO and Ninco Classics, the softest compound available should be used if no magnets are to be installed. Stock or Reprotec Classics are good choices. Use PMT and motor upgrades to improve lap times on these cars.2) For wider tire classics and GT such as FLY series cars stay with originals. Reprotec GT Super Racing type AS12309 are also very good on Ninco track. Silicones on smooth clean track is the way to go.
3) For Euro- sedans Cartrix treaded and slicks work best for me. You need to be especially careful that the tires don't dig in and flip the car rather then let it drift in the turns. CG lowering is critical here for good tire performance. Don't be afraid to use extra weight to get satisfactory results.
4) For F-1 cars Ninco originals work well for me. I use magnet tuning to get lower lap times.
5) For NASCAR original Scalextric tires/wheels. Keeps the cars equal. Magnet tuning matches any SCX Stockers to Scalextrics.
6) For rally cars I use originals, Ninco or Cartrix treaded. Keep things equal with PMT.
d. Track temperature/cleanliness: Cold tracks equal higher lap times on my Ninco track. Dirt and oil on the track really slows things down. I've stopped lubricating my cars and running immediately on the track. I now run the car on a spare piece of track at 6 volts for 20 seconds or so that any excess lubricant is slung off here instead of on the track. Before I start running on the track I wipe it down with a tack rag to remove dust (used to prep real cars for painting) and once a week I wipe it down with WD-40 to clean the rails and then use a soft scrub brush and alcohol and dry with lint free cloth to remove any residue (Fly GT tires don't like WD-40 very much). If you are familiar with chemical safety and use it in a well ventilated area, Carbon Tetracloride is one of the best solvents for cleaning track rails. Follow all the instructions on the container and use sparingly. As important as track cleanliness is for rubber compound tires it is twice so for silicones. Any dirt will severely degrade your tires performance so keep everything clean.
e. Rear tire size is often overlooked when performance tuning, but this factor can have a significant impact on your cars performance. First, remember that the larger the tire the lower the perceived axle to motor ratio. So 21 mm tires will give a lower ratio than 20 mm tires given the same pinion/crown gear tooth count and will move over a greater distance in one rotation of the tire. Second, larger tires raise the CG and move traction magnets away from the track rail reducing magnetic traction. Be careful, when you put on new tires, that you consider these two factors carefully. You may have to go back and performance tune for gear ratios and magnet down-force again
f. For front tires hard and smooth are good (see advice in general section). I use low profile tires on modern cars to reduce friction or harden stock tires with nail polish. (this is from the early days of slot cars. We used to do this back in the early 60's at our club track. I'm sure one of the real old guys might know where it originated from). The O-ring on the tire trick (general section) was first used in Da Nang, Vietnam in 1967-68 at a squadron slot track. We salvaged old Amphanol Connector environmental seal o-rings from F-4/F-105 aircraft, coated them with nail polish (we couldn't get shaving cream but there was plenty of Kotex and nail polish at the Base Exchange), and slipped them over the front tires to maintain realism but reduce sliding friction. Eventually in later years way after I left the sport, I guess realism fell by the wayside and O-ring tires became the norm. Today O-rings are readily available in all sizes. Find the thinnest ones that can be stretched over the tire and use them with nail polish or plastic cement. Sand as necessary to round and lower the profile. One last way to lower friction on a front tire is, while you are truing it on a drill, sand the tire down but leave a ridge at the outer edge or on the centerline. On Scalex and SCX fronts sanding off all the tread except for one bead works real well. This is all that will contact the track. Coat the ridge with nail polish or plastic cement and balance tire. To see if your front tires are slowing you down, just remove them and run some timed laps. If the times decrease then you need to work on the front tires and maybe front end setup.
g. This next suggestion Is for those who want that last ounce (or gram) of performance. As mentioned in step f, one of the things that robs your car of speed most in the turns is the front wheel / axle assembly since it tends to drag in the turns. Even independent rotating wheels can slow the car somewhat. So what can be done short of removing the front wheels altogether? Well the next best thing is to make the assembly as light as possible. If you are keeping the original front wheels which most of us tend to do then basically there are three areas. First, lighter axles; going to plastic or thin wall tubing can save a little weight. I use Aluminum tubing which is strong and light. Next we have the wheels. You have to be careful here because you don't want to damage them or weaken them to a point where they break. Since each wheel design is slightly different my advice here is general in nature. First, cut as much of the axle holder off as practical, usually flush with the rest of the wheel. Now, mount the wheel to the tubing axle and fit it to the chassis. Add thin wall plastic tubing spacers to remove front axle play. After this is set up remove it. Now take each wheel and make a series of drillings around the rim under where the tire will mount. Be careful not to drill in too deep or else you might drill through to the inner detail. Use a drill that's big enough to drill almost the width of the tire mount ridge minus a little on each side. If you are shy of using a drill here you can also use a Dremel grinder but be careful that you don't damage the wheel. Finally, and this will probably save the most weight, sand down the front tires as much as you can and still remain legal. Rubber is heavy and adds to the rolling mass. If you have access to sponge type tires these may further reduce weight. When finished you should have a fairly light front axle assembly. Remember for front wheels and tires, light weight is good.
7. Optional: Chassis Weight Reduction, Guide Shoe Modification and Chassis Strengthening
a. We weren't going to add this part until we got several questions about it, so here's some information on working the actual chassis itself. The procedures in this section are usually considered to be illegal in most race classes except the open ones. Most Euro Plastic chassis cars use a full pan configuration which though esthetically pleasing adds quit a bit of weight in the wrong place to the car. Most cars can gain as much as 2/10 of a second by removing excess plastic from their chassis (This varies from chassis to chassis type.). Before you get out the Dremels and X-actos though be aware that each car is different and the strength of the chassis can be destroyed by the wrong cut. Fortunately, modern plastic cements allow us to correct any major mistakes so let's go ahead. Also remember that many plastic chassis cars use the body for chassis rigidity. watch that you don't destroy this interface or if you have to, make sure that bracing is added to compensate for the changes. See diagrams in the Diagrams Section to see drawings of some of the lightening explained in this section.b. We didn't quite know how to handle this section because of the variety of different chassis. We finally decided to do it by using a couple of examples of popular cars. Number one, the McLaren GTR by Ninco. First, remove all parts from the chassis. Now, looking down to the top of the chassis, the first parts to remove are the side pods. Cut them completely off to the vertical member that runs from the rear to front axle carriers on both sides; DO NOT remove this vertical member. Next remove the pan material from just behind the front "radiator" to the forward mounting posts, staying away from the guide mount, and the plastic from in the little "triangles" on either side on the front. Fourth, remove all the plastic from the magnet well and forward to the front axle carriers but only as wide as the magnet. This leaves about 1/2 inch on either side from the motor mount to the front axle. Last, in the rear cut all the vertical plastic from around the exhaust/screen leaving only the section that fits into the body at the rear. If your rules allow lowering of the body, you should cut the front grillwork and rear exhaust detail off the chassis and glue them directly to the body. The chassis should now only connect to the body by the screw attach points and the 2 bearing posts at the rear of the interior. What you want to do is File/cut/grind off the screw posts in the body by about 1.5-2 mm so that the tires just clear the wheel wells. I just cut off the two bearing hold down posts because the bearings are glued into the chassis. If you make a mistake and cut off too much of the screw posts you can super glue a couple of washers onto the top of the chassis screw wells to raise the body back up. One caution, watch the screw length so the it doesn't go through to the top of the body. If you are in doubt cut the screw treads off a little. That's pretty much all that can be safely removed and still allow you to use a high torque motor such as a Cartrix PRO or Cheetah/Fox. You'll notice that we stayed away from the drivetrain area and the guide mount area. This is because these areas need to be strong as they handle the majority of the torque and track load. If you do make a mistake don't panic. Repair the area using plastic cement, not super glue or epoxy, but glue specifically for plastic. This glue essentially "re-melts" the plastic together with a bond as strong as or stronger than original. In some cases adding pieces of plastic with the glue will strengthen the joint even more.
c. Number two, the Ferrari 333 by SCX. This chassis is one of my favorites because it's strong and well balanced. The newer version with adjustable magnet lends itself well to magnet tuning. The first thing to do when lightening this chassis is to mark the outline of where the chassis overlaps the body so you don't cut that part. I use "whiteout" correction pen since it's easily removed later. You can also make your cuts with the body installed if you are careful. The first thing to do is hollow out the side chassis pods leaving about 1.5 mm all around. Next remove the plastic between the copper electrical "runs" from 1 mm in front of the motor mount to just behind the front axle. Finally, remove the plastic under where the front headlights are. This is a rough circle about 5mm on each side in front. You can expand this to the maximum with the body installed and used as a guide. That's about all you can safely remove. If you really want to get the max though you can also remove two small rectangular portions next to the motor inside the chassis uprights running between the front and back motor holders. With body lightening you can get the weight of this car to well under 3 oz.
d. General rules for lightening chassis:
1. Stay away from the drive train and guide mount areas. If you weaken these areas you risk breakage under race conditions.
2. Vertical members on a chassis provide rigidity so be cautious of cutting through them.
3. If the chassis is made from very flexible plastic you may have to add plastic members for rigidity after removing excess plastic from the pan.
4. No mistake is irreparable; If you make an error in cutting repair it with cement and plastic as necessary.
5. With practice you will learn what works and what doesn't.
e. The Guide Shoe: Here is some good information on improving your guide flag set up from Philippe de Lespinay who is a respected authority on both vintage and modern slot cars. We would like to take this opportunity to thank him for his input. This area may get it's own section in the next revision. We haven't tried this method exactly but we trust Philippe's knowledge on the subject.
" Most 1/32 scale cars come with a "snap-in" guide flag, and the tooling is so poorly engineered that the flag is very loose and rocks forward/backwards in its location. This causes undue wear and arcing to the pick-up brushes, which by the way are too narrow and too stiff, in their front or center. Replacing the flag by another only work if using a decent unit, I.E. NONE from the current 1/32 scale production cars at the notable exception of MRRC and Pro-Track.
1. The first thing to do is to remove the entire guide flag assembly and give
it to your dog to chew on. (joke)2. Then: Slip a 3/8' piece of 1/8" I.D. K&S brass tube inside guide hole on chassis. You can epoxy it if you wish, but it generally fits nice and tight.
3. Select a "proper" (straight shaft) guide, such as: MRRC, older Dynamic, Classic, Cox, Riggen...You may have to trim the frame some for clearance.
4. Slip it in and make sure that the flat surface is at the correct height. MILL the backing surface if necessary (I do this with the Classic guide which I believe is best suited).
5. Get some small bolt-on terminals at an electronic shop along with short 2-56 machine screws.
6. Remove the ridiculous little 'rivets' at the end of the lead wires, and solder the terminals instead. Easy on the solder joints, go to Soldering School if needed.
7. Get some serious 1/24 pro-braid at your local raceway or from your favorite, non-1/32 claustrophobic dealer ("what's a 1/24 scale car?")
8. Cut the end off the brass clip around the braid, and drill a small 1/16" hole through the remaining end.
9. Brush and comb the braid to have all the strands 'loose' and curve the ends oh-so-ever slightly downwards.
10. Tap the holes in the guide flag with a 2-56 tap (you can also use "press-on" guides like 'Jet-Flag' type, but it deforms the guide some and gives you false readings on how far your front wheels are off the ground. OK for 1/24 scale, marginal in 1/32 scale cars).
11. Slide the guide in place, slip the 2-56 machine screws through the terminals, then the braid, and bolt to the guide.
12. Go racing for several dozens of hours before you will ever have to replace the braid.
13. Check on http://electricdreams.freeservers.com/photo4.html for a photo of the resulting system on the winning (class destroying) Porsche 908/2 of Kathryn Walwick, set-up by yours truly. And by the way, this system works great but can be achieve by other means. However, one thing remains constant: do not attempt to use the existing flags on those cars, they are too narrow and will never provide decent
contact. "This is a pretty good "quick and dirty" on how to modify your cars guide to make it a winner. This is one more option you can try in an effort to get the car's guide and contact system to your liking.
f. Strengthening Portions of the Chassis - First we talk about lightening the chassis and now you may ask: why does he want to add weight? Well, the simple answer is that in certain configurations the chassis may have to be strengthened. When? Euro plastic chassis are good cheap designs, for the most part, that are strong within the range of snapin motors and accessories commonly utilized. But when we start hanging multi magnets off them and stuffing Cheetah motors in them then we soon uncover the inherent weaknesses in the plastic chassis design.
1. Guide Holder - When running high downforce magnet configurations and hot motors the guide attachment takes allot of pressure particularly on deslots. Sometimes the pressure exceeds the design limitations of the stock guide holder. If you break a guide holder and gluing doesn't fix the problem, you can make a new guide holder either out of brass plate (preferred) and tubing or sheet plastic and plastic tubing. (See Drawing) To do this:
a). Remove all parts of the old holder including the braces so that the chassis pan is flat and smooth in this area.
b). Next, measure out a piece of brass, plastic, fiberglass or carbon graphite sheeting to attach to this area (the top of the chassis).
c). Mark out a hole toward the outer end that is the same diameter as the tubing you are using and drill it out.
d). Now place a piece of tubing in the hole and cut to size relative to the guide axle. Attach this tubing with plastic cement or in the case of brass with solder.
e). Fit the guide and mount to chassis top taking care to make sure that the guide sits properly in the slot with the chassis on the track. once you've established this all fits correctly you are ready to glue the assembly to the chassis.
f). Use the strongest glue you have. In the case of the brass you may want to add some small screws countersunk from the bottom and attached with nuts.
2. The Drive Train - In inline configurations, motors such as the Cheetah generate enough torque to cause the chassis to "twist and flex" around the axle bushing carriers. This can cause a number of problems from gears mesh difficulties and striped gears to increased axle bearing friction and wheel hop. Even chassis failure can sometimes happen as the forces act on the chassis to cause fatigue cracks. So what can be done?
a). The problem can be alleviated in large part by adding reinforcement to the chassis in the form of extra plastic or stronger still, brass plating. By cutting pieces to fit under the rear axle from the motor extending aft for some amount and gluing these pieces to the chassis one can remove almost all of the undesired flex in the motor axle train. On most inline chassis this should be enough.
b). On some of the older SCX and Scalextric chassis made of softer plastic it may be necessary to add vertical portions to the axle carrier uprights also, attaching them to the previous mentioned plates. That's basically all you need to do.
c). You can get much fancier if you want and make motor attach braces and the like but for the range of power we're talking, this is really not necessary. Look at the SCX/16D drawing to get an idea how such upgrades should look. Other areas of the chassis can be strengthened in a similar manner.
d). Use sheet or scrap plastic if you need moderate strength and go to brass plate if you need max strength. Remember angle pieces of plastic or brass give more strength at a given size so consider using these types if you need allot of reinforcement in a small area.
8. Putting It All Together Back To Index
So now we come to the question: How do we put it all together? Well, let me illustrate with a couple of stories.a. First of all let's take what I call my Classic Class. Initially I had hoped to group all my cars older than the FLY Classic series into just one class but this soon became unreasonable when I began to build an Airfix Sprite using a Reprotec chassis from one of the stock Fiats. The fastest I could realistically get this car to run was 4.98sec on my track. I had already PMTed my other classics to an average time of 4.30-4.50sec per lap. What to do? Well, how about being able to tune for two lap time ranges. This is where I came up with the solution of adjustable magnets on all the Classic FLY cars. It was the best and easiest way to accomplish my goal there. How about the other classics? Well the Ferrari GTO (Pink Kar ) was no real problem. Just pop off the magnet ( I had glued a thin cylinder magnet to the bottom of the motor) and move it forward. The Reprotec Cobra was easy. Swap motor to an RX-4 type and that was it. The Ford GT (SCX) was just a matter of sliding the magnet I had added forward to the front of the motor. So in 10 minutes I could change all my Classics from the 4.30-4.50 sec range to the 4.90 -5.00sec range. One example of PMTing your cars once you know how.
b. How do you know what to do to your car to race tune it? Well let's again take the GTO as an example. When I first got my Ferrari GTO, I knew the motor was a real dog. Straight line speed was missing and it wasn't because the back wheels were spinning. I open the car up and my mood sank when I saw the motor that was installed. I couldn't see any way to easily upgrade the motor until I opened my newly purchased SCX reissue Ford GT and noticed how similar the motor adapters were. Sure enough they were interchangeable and after a little investigation I found out that an SCX adapter was in fact a normal upgrade item. Where can you find out this kind of information? In this article now. After this upgrade, I realized that I would need more rear traction. Wider tires were out of the question because I wanted some realism. My next choice was a traction magnet. Just looking at the car, one will notice that it sets rather high off the track. This made sticking a magnet to the bottom the obvious choice. I found the right place rather quickly ; on the bottom of the motor at the pinion end. I slid the magnet forward and ran several laps but in the end the rear position was the place so that's where I glued it. The car still had a nice smooth transition to drift but at a much higher speed. That's all It needed. I was in the speed range of my Fly Classic cars. I eventually went with an RX-41 motor (about 17,000rpm on my track) which ran cool with no problems. If I ever need more juice I can go to a PRO or NC-2 with adapter. So, knowing what to do to tune a car is a matter of translating your observations into solutions.
c. The next example for those into speed is one of my SCX Ferrari 333SPs. When I got these cars I wasn't expecting much because of some of the bad reviews where I had read about weak motor/too much magnet. Well, I was surprised. The cars had some ingenious items on the chassis. First, as delivered, it did have way too much magnet, but a quick look at a pamphlet that was sent with the car showed that the magnet was in a "trainer position" (for SCX's trainer unit). By turning the plastic holder 180 degrees the magnet became adjustable. The other item was a spring loaded guide shoe. At first this looked kind of gimmicky to me but I soon found that it really worked well. I did most of the general tuning items and found that this car could be made to run real fast. So, I decided to go for maximum tuning on one of the cars for my SCX Trainer Unit. First, I needed a motor with lots of torque. The obvious choice would have been the SCX Pro; everybody said so. Well I guess my years in the aircraft industry must have sharpened my powers of observation because I had my orange Reprotec Cobra open at the time for cleaning and I suddenly realized that the motor with adapters would snap right into the SCX chassis. I put the magnet back to full down, connected the motor wires and preceded to run 10 of the fastest laps ever on my track. Then I lost it in a turn for some reason and when I re-slotted it, it was vibrating badly. A quick inspection revealed that I had run one of the rear tires half off the rim. I'd never done that with a Euro-car before so I figured I must have been pulling some G's. I glued the tires to the wheels and after letting them dry overnight