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TR2/3/3A Whitworth Threads (as on the bolt)

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TR3MT

TR3MT

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Hello TR3 Aficionados--I have read all the threads (discussions) about Whitworth threads (fasteners) which are really interesting and on point but not quite what I am looking for. I have made a complete restoration of my TR3A (TS50260L) and over the years have always replaced a lost or missing nut, bolt or cap screw with a UNF (SAE) part that seemed to fit. The only exception I found was the mixture adjusting nut on the SU carburetor. I am just wondering if anyone has ever seen an inventory of where Whitworth threads were used. I used to think all post WWII cars exported from England to the US used UNF or UNC (SAE) hardware. After reading the threads it appears there were several exceptions.
Thanks for your interest,
TR3MT
 
I'm not aware of any Whitworth fasteners on Triumphs. It's a different story with an MG.
 
Brass starter nut, some of the heater nuts and bolts on top, I think, gauge knurled nuts on back of the case, and some of the SU car linkage.
 
In general, large bolts are SAE, while small screws are whitworth. So, 1/4" and larger are SAE. Smaller machine screws will be Whitworth. Then, a lot of repro parts will muddle the mix by throwing in an occasional metric, or SAE. Carbs are always odd...
 
My filler plugs on the rear lever shocks are an odd size? Nothing fits!
 
I've found BA and BSF screws and threads used here and there in the carburetors and distributor. I suspect that's what you mean by Whitworth. I've never found real Whitworth threads on anything in my TR4A. BA and BSF a 55 degree thread angle, which I think is the same as Whitworth, and use the same set of head sizes as Whitworth, but the heads are one size smaller--e.g., a 3/8" BSF bolt uses the same head as a Whitworth 5/16. The thread pitches are not the same.

If real Whitworth fasteners are used anywhere on the TRs, I'd be interested to know what and where.
 
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