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Rear brake rod thread size

Hello Folks

just a quickie hopefully.

After maybe not wasting some money on a set of Whitworth taps and dies I find out that non of then fit the rear brake rod :face_with_rolling_eyes: . I foolishly assumed it would be along the lines of most bolts on the bike and just be Whitworth and so didn't measure it. I need to run a die along it as the threads are a bit buggered and makes adjustment dodgy.

I attach a pic


Well if I'm not mistaken that is 28 TPI (the calliper was set at 0.500" !), although I don't make this type of measurement too often but it is at least 26 TPI. The shaft is 5.88 mm diameter across the threaded part. Any knowledge greatly appreciated.


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Re: Rear brake rod thread size

The brake rod thread is 5/16" x 26tpi Cycle thread...Whitworth threads are generally (but not always) into the aluminium components...The M20 has multiple thread forms (BA, BSF, Whitworth etc.) and sizes so it's always worth checking any thread before starting if you aren't sure..There is some thread information in the Technical Section of this site but they aren't all listed...Ian

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Re: Rear brake rod thread size

Cheers Ian, most helpful.


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Re: Rear brake rod thread size

If you have an original brass wing nut it is probably past it’s prime in terms of wear, but there is plenty enough material to tap it out an put a helicoil in.
Fortunately I found this out when mine gave up on a country lane, stripping out the final vestiges of thread and not in heavy traffic!!

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