Inside Hub treatment

[Barga Racing]

What does everyone currently do, if anything to the inside of their wheel hubs? We used to do nothing to the hub but we grooved the axles. Then last year we grooved the axles and threaded the hubs. This was pretty fast but I am always looking for new ideas. This year I inserted a piece of 3/32 polished rod through the hub and rolled wheel back and forth on counter top, the theory is that the heat created will melt any small imperfections back into the hub. We then polished with pipe cleaners dipped in graphite. The wheel spun for about 25 - 30 secs on a polished axle held in my fingers. I have not had a chance to do a whole set and put on a car to test but the wheel felt very smooth while spinning in my fingers. What is everyone else currently doing?

[Jewel]

I don't think I have the best answer but here is what I do. I use gage pin about 5 thousandths undersize and role the wheel on an granite block with the axel hole filed with graphite.

This is the Stan Pope method, burnish the ID. Then I match the axel to the wheel. I do this by inserting the polished axel into the wheel with lots of graphite then I spin up my bicycle wheel and run the wheel and axel on the tire tred. This I think mates up the axel wheel to each other and further polishes the ID of the wheel.

There must be a better way. I know some guys use a reamer exactly matched to the wheel ID and very gently role wheel on their pant leg using the reamer as an axel. This deburrs the axel hole ID but it may enlarge the hole and cause it to go out of round. I would love to know the best way.

[Barga Racing]

Apparently no one other than Myself and Jewel does anything to their hubs or is not willing to share this info. With the fantastic discussion about friction going on I would be interested to know if anyone has done any type of controlled test on what is the best type of inside hub treatment.[/quote]

[Barga Racing]

Apparently no one other than Myself and Jewel does anything to their hubs or is not willing to share this info. With the fantastic discussion about friction going on I would be interested to know if anyone has done any type of controlled test on what is the best type of inside hub treatment.

[Da Graphite Kid]

Sorry for the delay Bob
We use the Pro-Axle Tool from Max-V to sort through and size the axle holes first. We burnish (?) the inside of the wheel hub with pipe cleaners dipped in graphite and than match an axle to a wheel (after starightening, deburring and polishing the axle) and load it up with graphite and finger spin it. I try to get my boys to do this as many times as possible but three times seems to be their limit. After mounting them on the car body, we again fill the hubs with graphite and 'roll-in' the graphite prior to racing.

Da Graphite Kid
(Greg Walters)

[Mike Parrish]

Wooden Wonder,

I have tried all of those mods with the exception of the tapped hub. One thing I have been wanting to try is grind a reamer flute or boring bar to fit into the hub and plunge cut a relief in the hub, leaving only about .050"/.075" of contact area at the front & back of the hub. I will post more when I have tested.

One new thing I did this year with my daughters and mine, was coat the axles with a dry film graphite lube. It leaves a VERY thin coating of graphite on the axles. I had to test during the race. My daughters got 1st in stock, and I got 2nd in modified. I missed 1st by .007 sec. I was going for more consistent run times. Looking at the graph, it did help, but I want to verify with more testing.

Mike

[Jewel]

A reamer that fits the ID of the hub exactly or is slightly larger should make the axle hold ID round. The goal is to get a round hole concentric to the tread and parallel. It would also be nice to get the ID holes of the rear wheels to be very close in size so that your LBW Alignment process goes well. With this in mind it may be worth reaming all the axle holes of your wheels, or at least the rear wheels to the same size. One racer built that I know built two identical cars and oddly enough the only difference was that one car had axle hole ID’s of .093 and the other one had hole ID’s of .096. The car with ID’s of .096 was faster and got second place. This is strange because theory says that the .093 ID holes should be faster. I think the Alignment was better in the car with .096 holes, and better alignment may be the over whelming factor in our hunt for making the best car that we can.

The reaming operation may make some builders squirm because the axle ID is getting larger and increasing braking torque, however it may make the alignment process go better. However, considering a plunge cut to reduce surface area and friction may be an idea that runs counter to the physics analysis of friction, which as discussed is independent of surface area. This notion is one of the primary misconceptions that pinewood enthusiasts should learn to articulate clearly being one who has had trouble with this idea.

Polishing the axle hole is tricky because of the tendency to make the hole go out of round, however a gentle plastic polish if done skillfully could be a good thing. At jewelry supply stores I have seen watch face plastic polishes, this may be helpful. Stan Pope recommends but I have not been able to find it, and I don’t have experience using it. Jewelers rouge also comes in various grade, and I am not sure which is the best.

[Stan Pope]

I don't suggest polishing wheel tread. Concentric tooling marks help keep the front end stuck to the track. I did, for a while, but believe that I was incorrect. That drawing has been corrected.

Sensitive measurement of effects is a problem for most of us. Anyone have ideas on sensitive setups that can give repeatable measurements of wheel/axle friction? Key side conditions are typical operating wheel load, minimum of specialized equipment, modest cost. I'll share one such when I have time to type it up.