The Fly Riley Target/TelMex car needs a different gear ratio to get the top speed to match the Racer’s Riley without adding magnets to the motor‘s case.

To start this project the rear axle assembly is removed and disassembled. The wheels and bearing pull straight off the axle with a light force.

The crown gear is pressed off of the axle, and the knurling removed with a file from the center of the axle. While doing this I found the axle was bent 0.020” at the center, and needed to be straightened.

The Slot it gear has to be honed out to fit the end of the axle, about 0.0005” was removed. When the axle will start into the gear, the axle is tapped through the gear until the axle spline passes through the gear hub.

The gear hone is made from a piece of ½” by 1½” 400 grit sandpaper rolled up a little smaller than the axle and inserted halfway into the chuck. The sandpaper is torn at the chuck to allow the paper to unroll about half it’s circumference.

The sandpaper is inserted into the gear hub. Holding the gear loosely in your fingers, start the Dremel and run it at a medium speed. Slide the gear up and down the sandpaper without putting any sideways pressure on the gear.

Hone the gear for about 10 seconds and check the fit on the axle. Keep repeating this until the end of the axle fits into the gear freely.

Two 2/56 brass washers were reamed to fit the axle, for use as spacers between the wheels and axle bearings.

The armature shaft groove in the crown gear is widened 0.060” for clearance.

The rear axle was assembled and installed in the chassis. The rear wheels were trued up and the tires installed.

The rest of the set up was the same as in this article.

After a few laps it was apparent that this car would need more work. The Fly Gainsco car and the Sideway’s Riley cars all turned laps of 7.000 to 7.100 seconds.

This car, with heavy vibration under acceleration and braking, would barely turn laps of 7.700 seconds, plus the top speed was 2 mph slower.

I disassemble the car and started over. The first thing I noticed was the front tires were too large for the wheels and flopped around, I super glued them in place and re-sanded them.

The rear tires still needed more truing. When I checked the diameter of each tire I found one was 0.011” larger, 0.813” to 0.824”.

After all of this work the car now runs 7.450 to 7.500 seconds lap times at 12.7 mph. The car still vibrated under full acceleration and braking.

After one more trip to the tire sanding fixture and sanding skid pad, the tires are now almost perfectly true. The tires now have a 0.793” diameter.

The Fly tires sanded like a silicone tire, but crumble tire debris like a rubber tire.

The lap times dropped to 7.250 seconds. Cleaning the tires with lacquer thinner didn’t seem to help.

Cleaning the tires with WD 40, improved the lap times to 7.100 seconds, with a fast lap of 7.022 seconds @ 12.9 mph.

WD 40 has no effect on the performance of silicone tires, other than to clean them. The amount of performance improvement with the Fly tires is similar to the performance increase I get with Scalextric tires when they are cleaned with WD 40.

To remove the tin can sounding vibration noise of this car, I put a coat of G.E. Silicone II sealer on the top of the chassis body posts, and under the heads of the body screws. The interior was glued all around with Elmer’s glue to stop some of the vibration noise.

The car is now completely quiet and vibration free.