Free Pinewood Derby Speed Tips
The products and construction methods discussed on this web site have been developed to maximize performance of your Derby car. Before building your car, please consult your local derby rules, as some methods and/or products may not be allowed.
Free Tip #1 Reducing Contact Surface Area
One important thing you can do to improve the performance of your car is to reduce the contact surface area between the wheel and the axle. This is especially important if you are using a liquid lubricant. This is accomplished by altering the axle so that it looks like Figure 1.
The part of the axle where the groove is cut never touches the wheel. This feature significantly improves the performance, especially when using liquid lubricants but also has benefits when dry lubricants are used as well.
Follow these steps to create lightning speed axles:
1: This speed tip is best accomplished with a drill press. However, if you are very careful and precise you can do it with a power drill as well. The cuts you make in the axle must be absolutely straight. If you cut the groove on an angle then the wheel will tend to wobble as it turns.
2: Place a dark mark on the axle at 1/16th of an inch from the head. Place a second mark at 1/4th of an inch, as shown in Figure 2.
3: Clamp the axle in your drill press or power drill.
4: If using a drill press, line up the press table with the marks you made on the axle, as shown in Figure 3. Using a flat file, gently cut a groove in the axle to a depth of about 1/16th of an inch. Don’t cut the groove too deep, as it will weaken the axle.
5: Polish the axle using the method shown in "ULTIMATE SPEED SECRETS". The final product should look similar to the one shown in Figure 4.
Free Tip #2 A Word Regarding Mold #13 and #9
Official BSA® wheels are manufactured using a plastic mold injection process with 16 individual molds. The mold number associated with each wheel is stamped on the backside of each wheel. In the past I have suggested that wheels produced from mold #13 and #9 were defective, as shown in the figure below.
IMPORTANT UPDATE: It appears the quality issues associated with mold #13 and #9 have been corrected. I have examined thousands of wheels this year (2005). I have found very few defective wheels from these two mold numbers. I now feel confident in recommending both of these mold numbers for use in derby racing. However, please examine your wheels to be sure you did not get a set of defective #13 or #9 wheels that may have come from a previous year's stock. If you did, then get a new set of wheels.
Free Tip #3 Polish Axles Until They Shine Like Mirrors
As the car moves down the track, the wheels turn and rub on the axle shaft continually. It is essential that the axle surface be as smooth and shiny as possible. You need to polish... polish... polish! Polish those axles until they shine like mirrors! All competitive cars have polished axles, but some are polished better than others. Below, I will show you two methods for polishing axles, the Ultimate Polish and the traditional polishing method. We have used the Ultimate Polish method for several years and find it to be vastly superior to any other method out there.
P.S. This is a really great place for your child to do a major portion of the work. Be sure to teach principles as you work. It's important that they understand why each step in the building process in being performed. You might even have a contest to see who can make their axles shine the brightest! Remember to make the building process FUN!
The advantage in using the ultra fine grit sandpaper is clear. Polishing compounds, like pumice, are really on the same level as 1800 grit sandpaper. The traditional method recommends that you use 600 grit paper, and then complete the process by using something like pumice (1800 grit). To go from 600 grit to 1800 grit is a huge jump. You simply are not going to be able polish those fine scratches left behind by the 600 grit paper, if you skip all the way down the line to a polishing compound that is 1800 grit. By using successively finer sandpaper you obtain a much higher quality polish!
Finally, by completing your process using 2500 and 3000 grit sandpaper you will obtain the Ultimate Polish, which pumice cannot provide! These are higher quality, finer abrasives. Your axles will shine so brightly, you might need to wear sunglasses when looking at them. You will be amazed at the difference!
Free Tip #4 Extend the Wheel Base
In order to accomplish this modification you will need to drill a new set of axle holes in your wood block. The holes must be perfectly straight and aligned with each other on opposite sides of the car. This is best accomplished by using a Derby Worx Pro Body Jig (fully adjustable tool) or a Pro Body Tool. A drill press also works well for this if your block is square, but many people do not have access to one.
Extending the wheel base will give your car two powerful advantages over other cars. First: It allows you to place the weight farther to the rear of the car. The farther back you place the weight, the faster your car will go. The reasoning behind this tip is that as you push the weight farther up the track, your car gains potential energy. More Energy = More Speed
Second: A longer wheel base will make your car travel in a straighter line as it rolls down the track. The straighter it rolls, the less likely it will be to weave around and bump into the center guide rail. The shortest distance between the start and finish is a straight line. Fewer Bumps = More Speed
The holes need to be drilled 5/8th inch from either end of the block and 1/8th inch up from the bottom, as shown in Figures 10 and 11. The holes should be drilled using a #44 sized drill bit.
You can also visit our pinewood derby pre-drilled blocks where pre-drilled pine blocks and wedges are for sale.
Note: Please note that when you extend the wheel base, the center of gravity rule still applies. The center of gravity for your car should be between 1 inch and 1 ¼ inches in front of the rear axle. In this case, that location will be located farther to the rear of the car.