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MG MG Y Type - Correct threads on sump side wall

Hi

I found out just now, that the two threads that hold the(made of brass) stop of the clutch operating arrangement have been mis-treated by some funny guy.

5/16 BSF Bolts fit in the threads, as well as metric M8x1 ones do!

I might have to ReCoil / Helicoil the two threads and need to please know which one is correct.

Regards
Anton Piller



Anton Piller

Anton,

According to the various XPAG Fastener lists those 2 bolts are 8-1mm, 3/4" long with a 1/4" Whitworth head.

cheers
Stuart
Stuart Duncan

Thank you Stuart, for your quick reply.

Question: Where do I find one of those fastener lists please?

Cheers to you too
Anton
Anton Piller

Anton, your photos are often helpful as well as the discussions. Seems you have that return spring sitting nicely in its special little hole!
Yours,
John
(YA, Queensland).
J P Hall

Anton
There is a lot of info on the MG Enthusiasts site

https://www.mg-cars.org.uk/imgytr/techdata.shtml

Fasteners----
https://www.mg-cars.org.uk/imgytr/pdf/fastener.pdf

Cheers
willy
William Revit


Tnank you John, for the flowers!

Thank you Willy, for the two links!

Best
Anton YT 4220
Switzerland
Anton Piller

I blame Lord Nuffield. Who would have imagined he would saddle us with metric threads (and not even current metric!) and Whitworth heads on the fastenings around the engine? When Hotchkiss's UK plant was bought by Morris, I think in 1919, Nuffield was too mean to retool the French machines with UK thread standards. His engineers went for the easy way out, and just adapted the hexagon dimensions to BSW, so UK mechanics could work on the units. I have a friend who's an experienced engineer and PA/PB owner who did a lot of damage unwittingly - and then did a lot of helicoiling repairs...
Tim Griggs

Tim, the PA/PB, and all the other pre-war OHC cars, have Wolseley derived engines which use conventional (for us) BSF/BSW threads. The problematic fasteners with Metric fine threads and BSF/BSW heads were used on Morris derived engines only like the XPAG series.
ian thomson

The two threads are 5/16” BSF, because all parts of the clutch operating system, for RHD or LHD, were fitted at Abingdon, where they only used Imperial threads.
R WILSON

Thanks for the correction! :-)
Tim Griggs

Dear R. Wilson

I can confirm that you are right about the two Threads. They are 5/16 BSF - as I found out yesterday, on a frieds spare sump :o)

Anton
YT, Switzrland
Anton Piller

This thread was discussed between 28/03/2026 and 31/03/2026

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