Pinewood derby speed wheel inner bore treatment
Quite possibly the most overlooked speed trick is polishing the inner bores of your Pinewood Derby Speed Wheels. Not a lot of people think that the inside of the bore needs anything done to it. Looking at the outer tread, you can see all sorts of imperfections on the surface. The inside of the bore is subjected to the same conditions. The surface can be dirty with mold release and whatever else dust is exposed during the manufacturing process. We have even found dry cat food in one of our wheel containers purchased from the BSA store.
We suggest a 2 stage polishing method with a third stage finishing step based on your lube of choice. We have found average that an increase of speed as much as .015″ second from this process alone. Yes that much! And for factory weight wheels, this is how you get those 30 second spin times. We offer a complete pinewood wheel polish kit for those that would like that type of product.
There are guys out there that make their own pastes and even have used toothpaste. But the best and most appropriate abrasive is a liquid plastic polish. After all the wheel is plastic. You will need a medium grit polish, follow by a fine grit polish to make it near friction free. Be sure to thoroughly clean between abrasives as you don’t want to be polishing with a combination of both. And don’t forget to buff out the final polishing stage before going on to the third stage
Using the appropriate polishing instrument is just as important as the paste. Derby Dust was the first to bring the cotton polishing spears to the market and they have now become the standard for professional racers. If choosing to use the pipe cleaner method, be sure to get the cotton, extra fluffy pipe cleaner and not the nylon versions. Also be careful of the metal inner cores of pipe cleaners. If left exposed, then may scratch your bore as you thread it in. I have seen craft paper used in the past as the delivery method. Simply cut the head of a Q-tip off at an angle and the shaft will be almost exactly the diameter of the inner bore.
After the final polishing step is complete and you have buffed out any residual polishing paste, the final step is to treat your wheel for the type of lube you have. You either need to preload graphite into the bores of the wheels, or seal the wheels with a type of wax / ceramic polish so that the racing oil will not be absorbed by the wheel. This step is probably the most high guarded secret by pro racers. Even more secret than the “perfect” COG. Which product is used is not known, but this is the general concept of what is being done.
We still find it debatable on whether or not it is necessary to seal the plastic for graphite dry lube cars. The best answer I can give you is this. IF you thoroughly break in your graphite to the point where you know that there is graphite worked into the wheel and axle together, then no sealant for graphite is needed. If you want the less messy, only dust method, then seal your surface and dust a few times. Science says that graphite on graphite will be quicker than metal on plastic. If you build enough layers of lube, you will have that graphite on graphite rotation.
We are finding that many new Nano and Ceramic waxes are being introduced into the auto industry for paint protection. These waxes are paint, plastic, and metal friendly. We continue to test these new products to see if there any benefits to PWD application. Will update as we find out more.