Car Construction Rules
New Cars Only – You may not race a car built for any prior Pinewood Derby. All scouts must participate in building the car. It’s fine for moms and dads to help as they see fit, but wherever possible, the scouts should work on the car. Paying for pre-built cars is not in the Cub Scout spirit and is not allowed.
Official Parts Only – The car must be built using the wood, wheels, and axles provided in this year’s official Cub Scout kits. Special axles, wheels, or car bodies cannot be used.
Width and Length – The overall width of the car shall not exceed 2 ¾ inches. The overall length of the car shall not exceed 7 inches. No part of the car, including wheels and nails, can protrude outside of these dimensions. A car that is too wide can interfere with other cars on the track.
Height – Because the car must pass under a timing device, the car cannot be higher than 2 ¾ inches.
Weight – The weight of the car shall not exceed 5 ounces. The car may be hollowed out and built up to the maximum weight by the addition of wood or solid metal. Attach any additional material securely; if it falls off during racing it cannot be reattached. Cars go faster if the center of gravity is about 1 ¼ inches in front of the rear axle.
Track Clearance – The track has raised center guide strips to keep the cars in their own lanes. Your car must have a minimum bottom clearance of 3/8 of an inch or the bottom of the car will rub against the guide strip. The minimum width between the wheels is 1 ¾ inches. Cars that bind against the guide strip do not go fast.
Wheels and Axles – The wheels may be lightly sanded to smooth out mold marks. The wheel treads shall not be tapered, narrowed, rounded, or grooved. The wheel treads must be left flat. Old-style wheels are prohibited. Cars go faster if the mold mark is lightly sanded off to make the wheel round. Cars go faster if the wheel hub is lightly sanded and polished where it contacts the car. Polished axles let the wheels spin more freely than unpolished axles.
Wheel Base – There are precut grooves for the axles, but their use is not mandatory. Pay careful attention to Track Clearance and Maximum Car Length if you change the axle locations. There are two precut axle slots on the bottom of the car; one axle slot is closer to an end of the wood block than the other slot. Cars that use the slot closer to the end as the back of the car go faster.
Wheel bearings , washers, and bushings are prohibited. The car shall not ride on any type of suspension or springs. Cars that have a coating of graphite smudged on the car where the wheel contacts the car body go faster.
Car Front – It is not always obvious which end of the car is the front. Mark the front underside of the car with a capital F. This permits the race starter to face the car in the proper direction.
Details – Details such as steering wheels, drivers, decals, and painting are fine as long as these details do not exceed the length, width, height, and weight specifications. Cars with wet paint will not be accepted.
Attachments – The car must be freewheeling, with no starting devices. Only gravity can propel the car.
Lubrication – Only dry, powdered lubricants shall be used on the axles. Oil or other liquid lubricants are prohibited. No lubricants may be applied inside the building or after the car has been inspected. Lubricate your car at home. Cars that use graphite go faster than those that use none. Some folks like graphite that also contains molybendium.
Inspection – Each car must pass inspection by the official inspection committee before it will be allowed to compete. The inspectors have the right to disqualify those cars that do not meet these specifications. We will have some tools on hand for the scouts to repair or adjust their cars, time permitting. The intent of these rules is to provoke fair play, good sportsmanship, and fun for all.
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