Looking at part number 21773 in the 1959 Jubilee catalogue. Lock nut (for the front wheel) 7/16 x 26 x 3/16. I think 3/16 is the width of the nut and 26 refers to TPI, is 7/16 refer to the nut size? And would that be W, or UNF or BSF? also part no 21770, spacer 15mm x 3/8 thick. What does the metric measurement refer to? The soze of the hole? Thanks, so much to learn!
Been doing some research and…
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Anything like a wheelnut…
Anything like a wheelnut with safety implications they invariably used cycle with its fine threads which were less likely to come loose. Coarser threads mostly whitworth into alloy was usual .
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Whitworth into alloy
is correct, but when Norton went over to alloy heads for Dominators in '54, they continued to use the same BSF stud into the head below the exhaust port. It's the same part to end of Commando production. They pulled out of my head, and I had to get them both helicoiled. Long helicoil needed.
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WW into alloy
As Paul Staneven says above, its usually Whitworth into Alloy (except when...) on the cylinder head on the Lightweights too!
The exceptions are (a) The rocker oil feed banjo bolts are 5/16" BSF and (b) the cylinder head steady mounting studs - same BSF thread. Makes perfect sence....DOH
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Been doing some research and it looks like it’s BSC, confirmation would be great