[singleminded]

Andy. i'm flying out to Australia on holiday today.I'll post it when I get back..John

[andy]

apologies John, only just seen this pm sent, I do have one but a spare would be great thank you

[singleminded]

I made some nuts for a chap recently, if you need one let me have you address as a pm and I'll send one..john

[Greybeard]

It's a Whitform type thread, Andy. Same as used on the axle tubes of my '37 Lion.
http://www.tracytools.com/taps-and-dies/whitform-taps-dies?product_id=1130

Steve

[andy]

well, I re visited the situation, it is indeed 24 tpi and 3/4 " I looked also and couldn't match it up with anything, anyway I have a rear drum and sprocket in my bits pile for a 1920's 3.5hp, it has the bearing in place and the securing nut is of the correct size so all good, it is an odd size though

[iansoady]

My Machinery reference book doesn't list that combination as either BSF, CEI or UNF.

Probably a special, as many others are, for example the exhaust nuts on my Model 10 are something like 1.25 x 20 tpi.

It wouldn't be impossible to get a nut made (if that's what you need).

[andy]

Can someone tell me the thread size on the gearbox main shaft that the clutch bolts onto? the bike is a 4 speed 1932 model 9, it does have the pull clutch but I think the thread is the same size as the 3 speeds ??

The shaft is 3/4" and is 24tpi