There are six major factors that influence the speed of a Pinewood Derby car. Pay close attendtion to all six of these and you can build a winning car.
Major Speed Factors:
1. Body Design
2. Weight Placement
3. Wheel Preparation
4. Axle Preparation
Advanced Speed Techniques:
1. Rail Rider Alignment
2. Rear Wheel Canting
3. Advanced Friction Reduction
After your Pinewood Derby car is completely finished you must check the car′s alignment. It doesn’t matter how well or how fast you have built your car to this point… if you don’t properly align your car it will not be very fast. Without proper alignment the wheels will likely rub too hard against the car body and the track rail causing a braking effect and slowing the car down.
You will want your car to go as straight as possible, unless you have built a "Rail Rider". Rail Riding is a more complicated building and adjustment technique where the car actually rides against the rail all the way down the track. Contrary to how it sounds… this actually makes the car faster. To learn more about Rail Riding CLICK HERE
There are several alignment techniques for straight rolling Pinewood Derby cars. The easiest way is to place a 4 to 6 ft. long strip of masking tape onto a smooth board or table. You must prop one end of the board or table up about 3 inches. Then roll the car down the tape to see how straight it goes.
Hopefully you car will roll straight all the way down the tape line. If it does, then you’re finished with the alignment process. However, if the car veers to the left or right you should start making adjustments to the axles. You want to see if you can adjust the axles without having to bend them. Because once you bend an axle you can't go back without replacing it. Start by adjusting the front axles first. Take a Sharpie marker and mark all the axle heads with a small verical line pointing to the 12:00 position. This will help you know where you are at when you turn the head of the axle to adjust.
Using any hobby pliers or the Axle Pliers, turn either the right front or left front axle 1/4 of a turn and then roll the car again and see what results you get. If it still veers the same direction then try turning the other axle a 1/4 of a turn. Keep turning until you get a different or better result and try to get it to roll as straight as possible.
Adjust the front axles until you cannot make the car roll any straighter. You will then need to start adjusting the rear axles. If your car veers right then check to see if the left rear is turning out or right rear turning in. Adjust the one that looks most obvious and then test drive again. Experiment until you can get the car to go as straight as possible. Try not to turn the axles too much as you may loosen them in the slots.
If you cannot get the car to roll straight then you will need to bend an axle to correct this condition. Find the axle that causes the majority of problem… or select the dominant front axle and secure it in a vise, leaving about 1/4" outside of the jaws. Tap the axle lightly with a hammer. This axle will now be very aggressive in adjusting the alignment so make sure you bend the one that is causing the problem and adjust until your car goes straight for several feet.
After you have finished all alignment adjustments you should glue the axles into the slots taking care not to let the glue get into the wheel. You don't want an axle to fall out during the race.