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Race Tuning A Stock Car
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Much can be done to improve the
performance of a stock HO car without the use of hop-up equipment or modification parts of
any kind. Even when future modifications are contemplated, it is advisable first to be
sure the car to be modified is performing at its best as a stock car.
As you may have found already, the performance of all new stock cars is
not the same. Some perform much better than others. Following this check-list will do much
to bring the poorer-performing cars up to the level of the better ones.
Note that the items in the list do not take into account possible wear
due to normal use, but are concerned only with the factors that affect the performance of
cars that are in new or like-new condition. For best results, therefore, it is necessary
to start with either a new car or one that has been maintained carefully.
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| 1. Check front axle/wheels assembly for proper
adjustment. Slight end play should be present to avoid binding of the hubs against the
chassis. If necessary, relocate wheels to obtain correct adjustment. A drop of Aurora
Racing Oil or other lubricant at the points where the axle passes through the chassis will
also reduce friction. |
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| 2. With idler gear removed, spin rear wheels.
If all is well, they will run almost as freely as properly adjusted and lubricated front
wheels. Possible sources of friction at the rear, however, include not only improperly
adjusted wheels (which should have slight end play as in the front) but can also be due to
improper installation of the cluster gear assembly consisting of the driven gear, cluster
gear shaft and pinion drive gear. This is the assembly at the rear of the top plate. The
proper position of the small drive pinion on the underside of the top plate. Adjust the
position of this gear so that it floats freely between these two surfaces. |
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3. Remove motor brushes and carefully increase tension of
brush tension springs by gently pushing them into the brush retaining holes, from the
underside of the chassis. A pencil or similar pointed instrument may be used for this
purpose. Be sure adjusted tension is the same for both springs.
This May be checked by inserting a pair of new brushes into the
retaining holes and making sure that both extend to an equal distance above the chassis
floor. Readjust if necessary. Also, be sure the springs do not protrude so far into the
retainer holes that the brushes won't stay in position when the top plate is reinstalled. |
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| 4. Even in new cars, poor performance can be due to
magnets of substandard strength. The most positive and simple way to verify that this
problem isn't holding your car back, is to replace them temporarily with the magnets from
one of your best-performing cars. If no improvement results, the original magnets may be
assumed to be in good condition; otherwise, replacement is in order. If the car runs in
the wrong direction, simply swap positions of front and rear magnets. |
5. Occasionally, there have been reports of
"bad brushes", due not to wear but to some defect in manufacture not detectable
by visual inspection. If following the other suggestions in this check-list still leaves
your car with sub-standard performance, substitution of another pair of brushes may help. |
| 6. Check the guide pin for proper length. Excessive
length will cause de-slotting, especially at the track joints. Be sure the guide pin is
firmly attached to the chassis and body by a screw that does not touch the track surface. |
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| 7. Pickup-shoe inspection is the final step in
race-tuning a stock car. First, check that there are small coil springs under each pickup
shoe; then remove these springs and check their tension. Be careful when removing these
tiny springs - they will jump out and get lost if removed carelessly. Gently stretch the
springs to adjust their tension. Be sure that the adjusted tension is the same for both
springs. Reinstall the springs and pickup shoes. To clean the pick-up shoes, use an eraser
or an abrasive block; never use sandpaper or anything similar. |
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Checking each of the seven items on each
new car and adopting the check-list as part of your regular maintenance routine will
assure top performance of your cars, both stock and modified.
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