Axle hole mod / wheel surface prep

[JustSayin]

Two questions...

1. Is it advisable, or has anyone heard of slightly sanding/tapering the bottom half of the axle holes so that the wheel hub has less friction when touching the body of the car? Someone I know just did that for their derby race.

2. What's the consensus for the final prep on the tread of the wheels? Leaving them sanded? Buffing them with a liquid wax or graphite? Using Pledge? Other suggestions?

Thanks everyone!

 

[Pinewood Outlaw]

The other day was first I've heard of tapering the bottom of a axle hole. Looking at my 1/4" body and axle holes I'm suspect that sanding a taper at bottom of axle hole would compromise the integrity of the hole being able to properly hold axle at my 3 deg cant.

 

[Reecedad]

Two questions...

1. Is it advisable, or has anyone heard of slightly sanding/tapering the bottom half of the axle holes so that the wheel hub has less friction when touching the body of the car? Someone I know just did that for their derby race.

2. What's the consensus for the final prep on the tread of the wheels? Leaving them sanded? Buffing them with a liquid wax or graphite? Using Pledge? Other suggestions?

Thanks everyone!

Are you asking about the inner hub? Yes, if your rules allow you’ll find speed by coning the inner hub

 

[Charles Studer]

Hmmmm...I dont understand what you are asking. But the smaller the contact diameter of the inner hub, while maintaining concentricity, the less resistance those wheels will have to overcome.
As far as tread prep is concerned....that is a touchy subject for many. So basic round and smooth with minimal run out is best. Some like to lube a wheel and others not as much

 

[e/o]

I think JustSaying is not talking about the inner hub but the portion of the axle hole on the car side of the wheel that sticks out slightly past the wheel edge. Coning it would slightly reduce friction when that part of the wheel rubs against the body. But this isn’t a problem in the first place if your wheels migrate out.

 

[Craigs Cruzer]

If I am interpreting the question right, here is what I understand. The side of the car body is inherently flat, so the entire axle hub could rub around the entire axle hole. If you taper the bottom edge of the car below the axle hole using an x-acto knife, you can eliminate maybe 30-40% of the surface area the hub comes into contact with.

I only remember reading about this once and we have done this a couple times in the past. I haven’t done it recently as I’m not sure how much benefit it has or if it could have negative effects. In theory, it would reduce surface area for friction making the car faster. But it could also cause the wheel to not run smoothly as the hub is in contact with an uneven surface as it transitions back onto the surface that wasn’t removed. I haven’t done enough testing to know if the effects help, hurt, or are negligible.

I also take the following mindset with all things pinewood derby: if I’ve only seen it once or twice and it’s not something I can find anywhere on this forum, it's probably not something that is advised.

 

[JustSayin]

Craigs Cruzer is on point to what I'm asking. If you don't have bent axles and your running straight, does it make sense to taper/remove the bottom half of the car area below the axle hole to reduce friction when the wheel touches the body.

 

[Charles Studer]

I have experimented with this. I feel that if the relief is not perfect the possible benefit becomes a Big detriment quickly. Enough said.