Pinewood Derby Outer Wheel Hub
Another issue that can cause wobble is the outer hub. When properly aligned, the wheel’s outer hub will be pushed against the axle head. If the hub is not addressed in some manner, you could be losing speed because of that. There are numerous variations of hubs. Some are flat, some are coned, some are factory like with a reduction in surface area. Like always before, what will determine what you can use will be addressed in your pack rules.
The purpose of hub modification is to provide a smooth true surface for the axle to ride on and to minimize friction. By reducing the surface area in contact with the axle head, you reduce friction. This is done a few ways.
Rules can can sometimes specifically address this issue. They will simply come out and say no hub modification is allowed. Other rules state that both levels of the hub must be present. We made a hub profile that gives the benefit of the of the cone, but retains both steps of the outer hub. And most rules just plain don’t care. You need to decide what you can use then go from there.
To get the most out of your wheels, the bare minimum would be to “clean up” the outer most edge. Make sure it is uniform throughout the hub and eliminate the mold line to ensure true travel. Doesn’t HAVE to be done, but when thousands of a second matters, this can give you the edge. All wheels from Derby Dust come with some sort of wheel hub treatment because we want those thousands in your favor.
To clean up the top part of the outer hub where the wheel rides or even completely remove the top step of the hub, the use of 2 tools are needed. You will need the Derby Worx Pro Hub Tool and the Pro Hub Shaver. There are currently no aftermarket tools available to make a coned hub. This can only be done with a lathe and a tool designed to do this specific task.