Pinewood Derby Stories and Photos from Maximum Velocity
Understand Your Local Race Before Building Your Pinewood Derby Car
You have that Pinewood Derby kit in hand and you're ready to build a car. Will it be a racecar, a rocket, or maybe something a little crazier? You can let your imagination run wild - well almost. As in all of life there are written and unwritten rules that we must follow.
So put down the pencil or tool, set the wood block aside, and find out about your local race. Listed below are topics that you need to know before designing and building your car. Much of the information should be written in your local rules. The rest you can learn from the race leader.
Car Dimensions - Each race has rules for the maximum length, height, and width of your car. There should also be a rule for the minimum distance between the inside edges of the wheels. It is easy to take these measurements into account when you are designing and building the car, but very difficult to adjust them at the weigh-in. This problem was experienced first hand by a young car owner in our local race a few years ago. In our race, 3 inches is the maximum height. This young lady brought in a car that was carved to look like a duck, complete with a long curving neck. The car looked great! But unfortunately, it measured nearly 5 inches tall. What could we do? Amidst a few tears, the young lady gave us permission to 'operate' on the duck. So, we shortened the neck enough so that the car measured 3 inches tall. All in all, the situation ended well, but a simple check of the rules would have avoided this tearful situation.
Underbody Clearance - You may want to attach weight under your car, but with that weight attached the clearance specification must still be met. It is easy to recess weight into the bottom of the car as part of the building process, but much more difficult to do so at the weigh-in. Recently a car owner brought their car to the weigh-in with weight screwed to the bottom of their car. Unfortunately, the clearance specification was not met. The only option the car owner had at the weigh-in was to remove the weight and screw some of it on top of the car. Not only was the car underweight, but the car no longer looked as nice.
Maximum Allowable Weight (and have a plan to meet that weight) - Make sure you can easily add or remove weight from your car. It is very difficult to make large adjustments to the weight of your car after it is complete. I can think of many cases where cars were very much underweight or overweight at the weigh-in. As an example, I remember one car shaped to look like a bus that was made out of a fir board instead of the supplied pine block. Not only did this violate the rules, but since fir is much heavier than pine, the car was nearly double the maximum allowable weight! On the opposite extreme, many times cars have been brought to the weigh-in with no added weight. Frantic attempts were then made to add weight, with the end result being a damaged car.
Adding/Removing Weight - Find out if you will be able to add, or only remove weight at the weigh-in. If you are only allowed to remove weight, make sure your car is slightly overweight when you take it to the weigh-in.
Wheel Rules - Generally, you must use the wheels that come with your car kit, and most commonly the only wheel modification allowed is a light sanding. However, some races do allow more extensive wheel modifications, and if done well those modifications can improve speed. But know the rules, and don't modify the wheels unless the rules specifically allow wheel modifications.
Wheel Base Measurement - Generally, the wheel base (distance between the axle slots) on the supplied block must be used. But in some races the wheel base may be extended providing a speed and alignment advantage. If specifically allowed by your local rules, then by all means extend the wheel base. But don't do it unless specifically allowed by the rules.
Axle Slots / Holes - Even if extending the wheel base is not allowed, you may be allowed to replace the axle slots with axle holes as long as the wheel base is not changed. If allowed, and if you have access to a drill press, you may want to use axle holes as they simplify wheel mounting and alignment. But again, know the rules!
Track Configuration - Pinewood derby tracks come in several variations. The two predominant types are:
(A) Continuous slope from the starting line to the finish line, and (B) Slope at the starting line, a curved transition, and then a long flat portion to the finish line.
The track type does affect how the car should be built. For type A, the center of gravity of the car does not affect the speed of the car. Also, weighting the car to exactly 5 ounces is not as critical as other factors. But for type B, the best speed is attained by having the maximum weight, and by locating the center of gravity of the car approximately 1" in front of the rear axle.
Starting Procedure - In most races, the car owner places the car at the starting line and picks up the car at the finish line. If so, make sure the car owner understands how to place the car at the starting line, how to carry the car safely, and how to gently put the car back in the staging area.
Other rules: - Lubricants - Is a specific lubricant required?
- Washers/bushings - Can a bushing or washer be used on the axles? (Almost certainly a no answer)
- Accessories - Are decorative accessories allowed? Are there any restrictions?
- Car Number - Must the car number be put in a specific location?
Well, I think the point has been made that you need to understand your local race before building the car. So now that you understand your local race, pick up those pencils and tools, and start building those cars!