Author Topic: Thread gauges  (Read 1106 times)

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ROYC

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Thread gauges
« 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 ?
My bike is a 1958 A7SS

JulianS

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Re: Thread gauges
« Reply #1 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)

« Last Edit: 13 February, 2017, 20:17:35 by JulianS »

ROYC

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Re: Thread gauges
« Reply #2 on: 13 February, 2017, 20:21:40 »
Thanks Julian
My bike is a 1958 A7SS

JulianS

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Re: Thread gauges
« Reply #3 on: 13 February, 2017, 20:40:55 »
Almost forgot - oil pipe petrol pipe and petrol tap threads are BSP thread.

Arthur

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Re: Thread gauges
« Reply #4 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