Build a Fast Pinewood Derby Car
by Joe Gargiulo
First, you need to reduce friction. Friction is the enemy of speed. Reducing friction, increases speed. It sounds simple but there are many sources of friction that slows a pinewood derby car. Here’s how to build a fast Pinewood Derby Car in six easy steps.
This short how-to tutorial guide tells you how to reduce friction and maximize inertia to help you make a fast, competitive pinewood derby car. It is by no means a comprehensive list of speed secrets. As an engineer, I wrote a best selling book, Winning Pinewood Derby Secrets, that lists all the tips, tricks and the technical reasons that make your car fast (or slow), including notes on the physics of motion and Newton’s formulas. Since pinewood derby block dimensions are all the same, these speed tips apply to Cub Scouts, Awana Grand Prix, PineCar, Kub Car, Royal Rangers and Girl Scouts powder-puff pinewood derby cars.
Step 1: Reduce friction to speed up your car
Your pine wood derby car moves from the force of gravity and is slowed down from friction. Friction acts like brakes. Reduce friction and your car goes faster. Increase friction and your car slows down. Finding the sources of friction and finding ways to reduce it is the secret to a fast car. Here are some ways to reduce friction and increase speed.
Step 2: Lubricate Axles and Wheels
The easiest way to reduce friction is to lubricate the surfaces that cause friction. Lubrication is an essential part of pinewood derby racing. Purchase a tube of dry PRO Graphite with moly and shoot it onto the axle shaft and inside the wheel bore. Spin the wheel so the graphite works in. You will immediately notice a significant improvement in the wheel speed as it turns on the axle after applying graphite.
Step 3: Prepare and Polish Axles – Essential for Speed
Your wheels turn on Pinewood Derby Axles. If you are using the Cub Scout BSA Grand Prix car kit, then these axles are nothing more than nails. One of the biggest sources of friction is where the axles and wheel surfaces meet. It is important to make your axles as smooth as possible. The burr under the nail head will grind into the plastic wheels severely slowing your car. Be absolutely sure that the burr under the nail head and on the nail shaft is filed off. Once these areas are sanded off, polish the nail shaft and underside of the head to a mirror like finish.
Step 4: Balance and tune your Wheels to Maximize Speed
Imperfections in your Pinewood Derby Wheels cause friction in many areas. Sanding your wheels, however, can be tricky. If the wheels are not precision sanded, you can actually make matters worse. Turning your wheels on a lathe are the best way to remove imperfections and get a uniform, balanced and finely tuned pinewood derby wheel. The wheel is secured in the lathe and spun at a high speed, then it is sanded or shaved with a tool attachment. Wheel imperfections can also make your car veer left or right. Once again, lathed wheels will remove mold imperfections so each wheel rolls perfectly straight.
Step 5: Add Weight to Increase Inertia
Your car moves down the track from the force of gravity. If your car is too light, it will have less inertia in the flat part of the track. Be sure your car weighs as close to 5 oz as possible. Find someone with a scale, purchase an inexpensive scale or weigh your car at the Post Office. Add weights until the car block, along with the wheels and axles, is up to 5 oz. Don’t wait until race night to weigh your car! When I manage pinewood derby races, everyone is always a rushed at the last minute to weigh their cars to add (or subtract) weight. If you wait until the last minute, you may not have time to make your car the optimal weight. Don’t wait to add weight!
Step 6: Steer your Car Straight (or into the rail?)
Steering a pinewood derby car is challenging. First, gently roll your car along a floor that has straight lines, so you can see which way it is steering. If it veers to the right or left more than 2″ over 4 to 6 feet, the axles are crooked. Just like steering a car, you need to adjust the steering on your pinewood derby Car. To adjust steering, you must adjust one or more of the axles so the car rolls straight.