Bob and Listers,
For those who aren't familiar, *by definition*, Whitworth thread forms are
those where the angle of the threads is 55 degrees versus the 60 degrees of
of most modern threads. Therefore the five Whitworth Thread Forms
include...
*British Standard Whitworth (BSW)* - As mentioned as being used on the
generator bracket and not exclusive to the 100s.
*British Standard Fine (BSF)* - Most engine, transmission & suspension bolts
on 100s.
*British Standard Pipe Parallel (BSP)* *or (BSPP) *- Brass drain plugs and
valves, fuel and brake line fittings on most Healeys.
*British Standard Pipe Tapered (BSPT)* - As above but tapered, not used to
my knowledge on Healeys.
*British Standard Brass (BSB)* - Used in thin walled tubing and ALL have
26TPI no matter the diameter. The mounting post on Lucas SFT/SLT 576
driving lights would have been this thread form.
Other British Fasteners that are *NOT Whitworth* include...
*British Association (BA)* - Used in Healey instruments and fuel pumps. 47
1/2 degree angle of the threads.
*British Standard Cycle (BSC)* - Used on a lot of British motorcycles and
most but NOT ALL threads are 26 TPI. The angle of the threads is 60degrees.
Wikipedia lists BSC as Whitworth and they are WRONG.
*Cycle engineers Institute (CEI)* - Older cycle thread superseded by BSC.
The angle of the threads is 60 degrees.
The following two are what the British switched to after moving from the
Whitworth standard.
*Unified Coarse (UNC)* - Identical to American SAE Coarse and *
Interchangeable*. The angle of the threads is 60 degrees.
*Unified Fine (UNF)* - Identical to American SAE Fine and *Interchangeable*.
The angle of the threads is 60 degrees.
Cheers,
Curt
On Mon, Nov 30, 2009 at 7:54 AM, Bob <robertlarson@att.net> wrote:
> Five? Maybe more...
>
> There is BA (British Association) which is more metric than anything and
> doesn't use the 55 degree
> but is a British thread form.
>
> But, I would think, that there is for sure a 6th. CEI (Cycle Engineers
> Institute) or BSC (British
> Standard Cycle)
>
> Bob
> 55 BN1 and Whitworth equipped Motorcycles. Triumph, BSA, Norton,
> Matchless, Royal Enfield
>
> Curt/Nancy Arndt wrote:
>
>> Bob,
>>
>> Whitworth in that I beleive they are BSPP (British Standard Pipe
>> Parallel.)
>>
>>
>> Remember there are five different Whitworth thread forms, i.e. BSW, BSF,
>> BSPP, BSPT, and BSB (British Standard Brass.)
>>
>> British Standard Fine is the most common on the 100s, followed by Bripish
>> Standard Pipe Parallel, and a few British standard Whitworth.
>>
>> Cheers,
>>
>> Curt
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