BSA Owners' Club Forum

General => The Star and Garter => Topic started by: ROYC on 13 February, 2017, 19:42:11

Title: Thread gauges
Post by: ROYC on 13 February, 2017, 19:42:11
I want to order a set of thread gauges to use on my 1958 BSA.
What threads are used on BSA's ?
Title: Re: Thread gauges
Post by: JulianS on 13 February, 2017, 20:13:47
These are some of the common ones.

Lots of British standard cycle in 26 tpi up to 3/8 diameter and 26 tpi and 20 tpi over 3/8.

Some BSF - notably the cylinder head bolts  and crankshaft sludge trap. Lucas stuff usually BSF and BA.

Whitworth coarse usually for threads in alloy casings.

The pressure relief valve is unusual - it is 7/8 x 16tpi UNS (Unified National Special)

The thread on the speedo head cable connection is metric 12 mm x 1 mm pitch. ( Gearbox end is BSCy)

Title: Re: Thread gauges
Post by: ROYC on 13 February, 2017, 20:21:40
Thanks Julian
Title: Re: Thread gauges
Post by: JulianS on 13 February, 2017, 20:40:55
Almost forgot - oil pipe petrol pipe and petrol tap threads are BSP thread.
Title: Re: Thread gauges
Post by: Arthur on 14 February, 2017, 12:14:17
I want to order a set of thread gauges to use on my 1958 BSA.
What threads are used on BSA's ?
You can get combined metric and imperial thread gauges - you only need one set of imperial gauges because they can be used whatever the thread form, ie BSF, BSW, BSP, UNF, UNC, ANS, etc