b.s.a.c15 gearchange spring anchor bolt

[mossy]

hi guys,i have had to have weld/repair to my crankcase (gearbox side) on my b.s.a.c15 (1964 ish) I have now got to tap out hole for the gearbox spring anchor bolt,i have the bolt in good order but does anyone know what the threads are,i believe it could be 5/16"u.n.f. is this correct? cheers guys.

[L.A.B.]

As you have the bolt then why not measure the threads per inch (TPI)?

1964 sounds a little early for it to be UNF so what is the TPI of this 5/16" bolt?

[mossy]

sorry I,m not that technicly minded.but I,ll try ,it looks like 18 and measures 5/16ths across. regards steve

[TGR90B]

That would be 5/16 whitworth.

[mossy]

thank you so much.regards steve

[iansoady]

A thread gauge will only cost you a few quid and is invaluable for this sort of thing. Together with a cheap digital caliper you can be sure about what you're dealing with.