Pinewood Derby Speed Tips - page 1

How to Build a Fast Pinewood Derby Car

If you want to build a really fast Pinewood Derby car there are several factors that you must pay special attention too. That’s what we will address on this section.

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
      5. Lubrication/Friction
      6. Alignment


Advanced Speed Techniques:

      1. Rail Rider Alignment
      2. Rear Wheel Canting
      3. Advanced Friction Reduction


Before We Start

Make absolutely certain that you fully understand the rules for your particular race. There are many sets of Pinewood Derby rules on the internet with certain important variations so don’t just go by any set of rules that you just found. Get your pack rules. Some packs will permit broad modifications to the wheels and axles. Some packs may only allow minor modifications. There is utterly nothing more disappointing than seeing your son’s car disqualified at check-in because you didn’t carefully follow the rules. Now let’s get started.

I. Body Design

There is a controversy regarding the importance of aerodynamics and Pinewood Derby racing. Some believe the car is too small and not achieving great enough speeds where aerodynamics makes any difference. Others are convinced that having an aerodynamic car design creates a huge speed advantage. Both sides can offer statistics and research to back up their positions. At Derby Monkey Garage, we are convinced that aerodynamics plays a definite roll in car speed.

Derby Monkey Garage builds all of its “Xtreme Speed Series” cars with a very low profile body at only ¼″ thick. This creates an extremely aerodynamic car that should cut through the wind with ease as it races down the track.

A low profile car design also reduces the wood weight of the car allowing a wise builder to place tungsten weights exactly where it’s needed in order to place the center of gravity at the optimum location.

The Derby Monkey believes a Pinewood Derby car should be designed to move as xyzlittle air as possible as it speeds down the track. When we compare two cars with identical characteristics, except that one car has better aerodynamics, the car with good aerodynamics always seems to perform better. Pinewood Derby races are often won, and lost, by only a thousandth of a second so every little bit of speed increase is worth the effort. Car 1 in the illustration is much less aerodynamic than car 2. There is no doubt that car 2 will be faster if all other factors are equal.

While you are planning your sleek car body design you must keep something in mind.  What weight are you going to use and where are you going to put it?  Too many times I have seen a dad cut out a great looking car body only to discover later that he does not have enough room to add the required weight.  This is where tungsten comes in.  Tungsten cubes and cylinders work great for thin bodies.  They allow you to put more weight in less space.

Your young scout may have already drawn or envisioned a super cool looking car that he wants you to build. Before it’s too late, you should discuss this idea with him. The best looking cars are seldom the fastest cars.

However, with a cool paint job, you can make a thin body car look awesome. But also remember, the Pinewood Derby experience is for the father and son to work together. If it means more to him to have the car design he wants then build it. You can always build your own car and enter it in the open class.

Follow these important factors while planning and building your car in order to make it as aerodynamic as possible.

1. Design a car body that is as low-profile as possible, we go 1/4″ thick.
2. Use tungsten to weight the car because a little bit goes a long way.
3. Round and smooth all edges of the car.
4. Do not ad accessories such as drivers, flags, engines, spoilers, etc. These only act like parachutes slowing the car down.
5. Fill holes and pockets with body putty, wood filler, bondo, glue or foam sealer.

Extended Wheelbase

Car #1 has a standard wheelbase of 4 3/8” while Car #2 has an extended wheelbase

Extended Wheelbase


The top body has the standard BSA Pinewood Derby axle slots at about 4 3/8” apart which is the standard BSA wheelbase. The axle slots on the bottom body have been extended to the maximum wheelbase. For a standard BSA kit block, the new axle slots, or wholes, will be place at 5/8” from each end of the car body. Make sure that the overall length of the finished car does not exceed the 7” restriction. The old axle slots may then be filled in with wood filler or body putty. 

Car #1 has a standard wheelbase of 4 3/8” while Car #2 has an extended wheelbase Your pack’s Pinewood Derby rules will have a lot to do with this one. In your “Homework” stage, you determined if you are permitted to modify your wheel base. Some rules allow you modify your wheelbase as long as the car, including the wheels, does not violate the 7 inch maximum length rule.

If you can, you must extend the wheel base as much as possible.

In the image below: the bottom view of the top body shows the standard axle slots at about 4 3/8” apart. The axle slots on the bottom body have been extended to the maximum wheelbase. For a standard BSA kit block, the new axle slots, or wholes, will be place at 5/8” from each end of the car body. Make sure that the overall length of the finished car does not exceed the 7” restriction. The old axle slots may then be filled in with wood filler or body putty.

The standard wheelbase on the block from the BSA Kit is 4 3/8 inches. This short wheelbase decreases the stability of the car. This instability will cause the car to bounce back and forth, left to right, slamming itself against the center rail. This action scruffs off a tremendous amount of speed.

Wheelbase



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