Reduce Wheel to Car Body Friction

One thing that slows the speed of a Pinewood Derby car is the fiction created where the inside wheel hub rubs the car body. So, the question is… As the wheel rubs against the axel head and then slides to the inside against the car, how should that surface be prepped?

The best solution is to align your car so that the wheels never rub against the body in the first place.  You can achieve this by bending (canting) the axles adding positive camber to the wheels.  In other words, the wheels will lean in at the top.  When the race starts, the wheels are forced to migrate out away from the car body and toward the axle head. 

This technique is good however; you are only changing the point of friction from wheel to body to wheels to axle.  With this in mind, you must polish the inside of the axle head very well.  The axle head can be polished to a much more friction free surface than the wood body.

Canting the wheels is still no guarantee that the wheels will not occasionally strike the car body.  Also, some racers do not feel comfortable with axle bending, canting and detailed alignment. So, it’s a very good idea to make wheel bore to car body friction as little as possible.

There are several methods used that produce good results.  Some of the following techniques may not be permitted by your pack rules.  Carefully study your rules to determine which of the following techniques me be disallowed.

1. Bushings:  You can recess a hard bushing into the car body around the axle holes.  Buff the bushing surface to super slick shine. This may be the best method however; most Pinewood Derby rules prohibit the use of bushings and washers.

1. Free Spinning Washers: You can place a small polished free spinning washer on the axel between body and wheel hub. Again, most Pinewood Derby rules prohibit the use of bushings and washers so please check your rules.

1. Hard Nail Polish: Place multiple coats of clear nail polish on top of the final coat of paint.  Then rub extra fine Pinewood Derby graphite into the hardened nail polish.  This may be the best legal way to treat that area of your car. This process is usually legal for any Pinewood Derby race.

1. Decals: A clear decal or sticker affixed to the body with a needle hole through the center. Then spray several coats of clear enamel or lacquer over it.  This works we however, the decal may be viewed as a bearing to the judges.

1. Metallic Striping Tape: Metallic striping or pin striping tape placed along the side of the body covering the axle holes makes an excellent friction free surface.  The metallic surface serves the same purpose as a bushing so you may have to defend it as just decorations if opposed by officials.

1. Hard Enamel: Paint the car with hard enamel and polish with extra fine sandpaper around the axle holes.  You should start polishing with about 2000 grit and work your way up to 4000 to 12,000.  Micro-Mesh sandpaper is excellent for this. This process is usually legal for any Pinewood Derby race.

1. Graphite Embedded Wood: Leave the wood unpainted around the axle holes and then rub in extra fine graphite. You can rub the graphite in with your finger. Many racers use this technique and it works quite well.  This process is usually legal for any Pinewood Derby race.

You can also perform some modifications on your wheels to help reuse this type of friction.  The new style BSA wheels already come with coned hubs so that there is minimal contact between the hub and the body.  It is still a good idea to polish the outer edge of the hub where it touches the body.  You can use any premium plastic polish like Micro Gloss or Micro Finish.

Good luck and good racing!

For great friction reducuing products visit Derby Monkey Garage

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