Cobras and Chickens
What’s your personal
preference with your slot cars – absolute accuracy, or good performance? Trade-offs abound in this hobby, and battles
will always rage between the purists and the racers. Some want to go fast, some want to preserve the originality of
their cars. I like the cars to be as
stock as possible, but I recently faced a situation and a choice that I don’t
like to make.
One
of the first purchases I made when I got into this hobby was Monogram’s
beautiful Shelby Cobra GT. I was so
excited when I saw this car that I bought it well before I’d be able to run it,
since I was still far from finishing my track.
Now with the track completed, I’ve been able to put hundreds of hours
driving time on a huge variety of cars, with the exception of, you guessed it,
the Shelby Cobra GT.
On
the routed track the car hopped miserably, and no amount of tire truing, weight
tuning, guide adjusting, axle modifying, bushing gluing, etc. could keep this
car in the slot. I even considered
sacrificing a live chicken. I had also
heard from a few informed sources that the spare tire sitting in the rear of
the car was the culprit, and removing this tire would not only restore the
car’s balance by lowering its center of gravity, but it would also spare one
live and very frightened chicken.
Until
now, I was positive that I would never get the car to run well because I would
never crack it open and take out the tire.
Such great detail is not to be spoiled by the desire to race! So, after the millionth hopping de-slot,
followed by a brief but harsh introduction to the concrete below, I decided
that a little planned damage would be better than the total and accidental
demolition of the Cobra.
This
is where it gets scary for the purists, so if you’re in that group of
enthusiasts, please cover your eyes, or cozy up to the nearest unmodified Fly
Porsche 917. I decided to do both – to
do some cutting to lower the center of gravity AND maintain the original look
of the car. To lower the center of
gravity, I could either remove the spare tire and wheel, or I could lower
the spare tire and wheel within its compartment. Lowering it won’t solve the issue altogether, but it will help.
To
get at the tire, use a soldering iron to undo the plastic joints holding the
interior tray to the body. As luck
would have it, the spare tire is mounted with a piece of axle stuck in the
wheel, and that chunk of axle goes through a hole in the interior pan. In other words, Monogram already cut a pilot
hole in the pan exactly where we needed it.
An Exacto blade is good right here to scribe a line around the
tire. Once that’s done, remove the tire
and post. Now, using progressively
larger drill bits, drill out the pilot hole until you can use a Dremel grinding
bit. Grind out plastic until you reach
your scribed circle. Be careful not to
do this too quickly, or the hole won’t be circular, and will probably look
goofy. If you make an error in any
particular direction, make it towards the front end of the car – it won’t hurt
to move the center of gravity further forward, especially since the spare wheel
sits behind the rear axle.
Once the hole is large enough, press fit your spare tire into that hole so that half the tire protrudes underneath the interior tray. Seen from above, all the detail of the wheel and tire is preserved, but your center of gravity is lower than it was before. It’s not fantastic, but it’s definitely better. My lap times improved quickly after making this change, and the car is no longer a nightmare to drive on the routed track. Maybe this improvement will save me some cracked plastic, and it should improve the state of mind of the chicken.
Here’s the final result from underneath. The tire is lowered by 3/8” or so. The car is happier, I’m happier, the chicken is happier. Glue it all back in, and you’re set to go!
