Hubcap threads

[Philip Allen]

Can someone please confirm the thread size for the hubcaps please? I believe they are M20x1.5.

I have found that when trying to fit the caps to the wheel assembly they bind up hard halfway down requiring a pair of stilsons to remove them again. So I think that I will need to clear the treads with a suitable tap.

[Phil Woollard]

Hi Philip, aluminium on aluminium "picks up" real bad , use a rotary wire brush and buff the hell out of the male thread, Then use a light oil to lubricate and they should screw in just fine using only your fingers. If you have damaged the thread then you may have to tap the female.

[Armortek]

Good advise above from Phil.

The thread on CK0209 is M22 x 1.5 (fine pitch)

[Philip Allen]

Thanks for the info guys, much appreciated.

[mark lawson]

Using a light application of copper slip is always a good idea on alloy.

[Robert Reid]

I keep a set of taps on the bench and chase a lot of threads.

They come from the factory very nice... but it only takes a sliver to gall Aluminum. And there are chips here and there to be found...

Also, having compressed air at the bench is a great idea. If you don't have a compressor or an air line, you can get a small "Air Tanks" from the auto parts store for short $$. Fill it with 80 LBS of air and it will run an air chuck (blower) for days... Blowing out the holes is a good idea!

But hard to beat running a tap down holes just because.

Cheers,

RPR

[Michael Allen]

I have cleaned all the hubcap parts, wire brushed them on a lathe, scrapped out the threads, oiled the threads, copper greased the threads and blown them out with compressed air. Despite all this I just cannot get the caps to close within 2/3 mm of the back plates when tightening firmly by hand. Is this gap ok or is there more I can do? I don’t possess taps and dies of this size.

Many thanks

[Jerry Carducci]

I've not yet got into my KT kit however depending on how the hubcap thread is made, assuming there's a flange, the thread may be cut without a relief cut and it won't cinch up tight as the thread ends. If that is the case you could, very carefully, use your lath to cut a very thin relief cut just in front of the flange. That would allow the hubcap to tighten completely.

Jerry

[Michael Allen]

Thanks Jerry.

I wonder what everyone also did?

[Jerry Carducci]

Thanks Jerry.

I wonder what everyone also did?

Either they forced it, didn't have the problem or did and just left it. I've found the latter more often than not but like you I don't like it. On the 88 I'm rebuilding several parts that should tighten without gaps needed relief cuts (or rebate cuts - the technical term slips my mind).

I suppose one cut cut a relief on the female side but without a way of re-cutting the thread I'd shy away from suggesting that one.

Jerry

[Jerry Carducci]

I should have called it an undercut.

This should be able to explain it better than I could.

Undercut

Jerry

[Michael Allen]

Jerry

Many thanks for your assistance.

I’ve neither the skills or the nerve for that solution. I have cleaned all the threads, wire brushes them all, scrapped out every millimetre of thread with a very small file, I’ve deburred the back plate thread, blown them
out with compressed air and oiled all the threads. All of them tighten up a little over 1 mm short of the back plates when tightened by hand. I’ve no idea if this is by design or not or what will happen when I put the grips on them but I can see no choice but to leave them. Should I be using Loctite for these parts? It doesn’t say so in the instructions but I can’t see why not.