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Motorcycle Discussions => British Bikes => Topic started by: mossy on June 14, 2018, 10:36:09 AM

Title: b.s.a.c15 gearchange spring anchor bolt
Post by: mossy on June 14, 2018, 10:36:09 AM

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.

Title: Re: b.s.a.c15 gearchange spring anchor bolt
Post by: L.A.B. on June 14, 2018, 10:48:07 AM

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?

Title: Re: b.s.a.c15 gearchange spring anchor bolt
Post by: mossy on June 14, 2018, 05:20:03 PM

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

Title: Re: b.s.a.c15 gearchange spring anchor bolt
Post by: TGR90B on June 14, 2018, 06:08:30 PM

That would be 5/16 whitworth.

Title: Re: b.s.a.c15 gearchange spring anchor bolt
Post by: mossy on June 14, 2018, 07:33:59 PM

thank you so much.regards steve

Title: Re: b.s.a.c15 gearchange spring anchor bolt
Post by: iansoady on June 15, 2018, 05:22:19 PM

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.