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MG MGB Technical - Thread Size of Clutch Pipe lock nut

What is the thread size for the large nut that locks the clutch flexi-pipe to the chassis bracket? It looks to be a very fine thread, finer than the usual UNF fittings. Unfortunately I had to cut the old nut off and threw it out so I haven't anything to go on except the end of the new pipe.
Mike Howlett

Stuff like that is usually 'funny' thread and spanner sizes, probably BSP, and IME the spanners are often different from original to replacements.

I take it the new hose didn't come with nut and star washer, some do. Some of the usual suspects also sell a fitting kit of nut, star washer, and copper washer for the slave end, Google 'mgb clutch flex hose nut'.
paulh4

just measured a hose i had here---5/8" x 18tpi
fairly universally used nut on Mg's, mini's etc for clutch and brake hoses
William Revit

There you go, thanks Willy, live and learn! 5/8 UNF, it always seemed much finer than that to me but I had always ordered the nut by part no and never bothered measuring ... or thinking :).
Paul Walbran

Hmmm--you've got me thinking now, this is a new hose from a local supplier, maybe the thread is different---like you I remember them being a finer thread-----i think
William Revit

Panic over! I have found a nut that fits in my extensive collection of (mostly) car rubbish.
Mike Howlett

Ok, went and measured those in my stock, take the original nut.
Imperial pitch gauge at home jumps from 24 (is too coarse) to 27 (too fine). Did a count and measure, 15 threads came to 15.3 mm as near as I could make if, so sounds like 25tpi.
Paul Walbran

Whilst the spanner sizes can vary when replacing hydraulic hoses in my experience, I can't really see the thread changing or they wouldn't fit existing components.
paulh4

In that sense the thread concerned is stand-alone if it has a matching nut, which in Willy's example being 5/8unf would be relatively easy.

We come across such cataloguing errors from time to time with aftermarket products especially in mechanical lines where there is scope for generic and "this is close enough to do the job" items. Sometimes not enough homework is done in the cross-referencing and the supposed right part that is identified isn't quite up to it.
Paul Walbran

The hose I have here is definately 5/8 x 18 (unf)
It did come with a nut and a shakeproof washer---so they probably knew it was different(wrong)
Doesn't have a brand name on it so probably--china?
William Revit

This thread was discussed between 28/02/2022 and 05/03/2022

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