Hub to axle clearance, lubes, etc.

[FinePine]

Hello all,

It's time again for my company's PWD, but this year they have changed the derby class rules significantly to prevent me from doing my thing with the lathe. No wheel or axle mods other than a tread polish and axle burr removal and polish will be allowed. Despite this attempt to make the cars more uniform, there are two types of kits being handed out- some left overs from last year, which were from Pinewood Extreme (now defunct, I think), and this year's, from PinePro. There are significant differences in the wheels and axles in the two kits. Most interesting is that the axles and wheel bores are several thousandths larger in the PinePro kits. The older kits have wheels from decommissioned BSA molds (when was the change, 1990 or thereabouts?) So, I have the opportunity to mix and match wheels and axles from these two kits.

The most obvious combination is to use the larger diameter axles with the smaller bore wheels in order to reduce the clearance between the axle and bore. I'm thinking that the difference in diameters after polishing would be around .003". I don't have the parts on hand right now to verify that number, but in any case the clearance would be much reduced. My questions for you that have experience are: is this a good thing, and what would be the ideal clearance?

It seems to me that this would be a good thing indeed, but it's always a good idea to check against experience.

Further, what lube would be best for reduced clearance? Would the viscosity of an oil be harmful in a reduced clearance setup, where a larger surface area will be "almost touching"? From what I've read on this board, it seems that Krytox is hit or miss, and is potentially slower than graphite if application and surface prep aren't just right.

Any insight or thoughts you have are very welcome.

[FatSebastian]

From what I've read on this board, it seems that Krytox is hit or miss, and is potentially slower than graphite if application and surface prep aren't just right.

My recollection of DT discussions is that Krytox is more forgiving and much less finicky than NyOil.

[FinePine]

Thanks for the links.

I think this is one of the threads I was reading:

I have a nearly full bottle of NyOil, so would prefer not to buy Krytox, but if it is really the safe bet, I will. Hate messing with graphite.

[pwrd by tungsten]

0.004 works well...

Krytox easier to use than NyOil.

However graphite can be better than oil unless you do it right...

[murphken]

We are having no luck with graphite in the hot, humid summer. Times have gone up with graphite over the last two months.

It is very difficult to get the graphite to even go down between the bore and axle. Large flake graphite has not been working. It just sits there. Small flake graphite at least moves down the bore and helps out a bit.

This is life south of the Mason-Dixon Line!