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MG TD TF 1500 - TD/TF Gearbox Brass Drain Plug Thread

Could someone tell me the correct, original thread type and size for the brass TD/TF oil drain plug of the Gearbox?

Cheers
Rob Grantham
Rob Grantham

I believe it is 1/2-14 British Standard Pipe.

Tom Lange
MGT Repair
t lange

Some discussion here that it is 1-5/32 x 13

https://www.mg-cars.org.uk/mgtd/mgtd_search_request2.php?subject=8&subjectar=8&thread=2012022016411617633
Christopher Couper

For some reason that link doesn't work for me. Try this one:

https://mg-cars.org.uk/cgi-bin/or17?runprog=mgbbs&access=&mode=archiveth&subject=8&subjectar=8&thread=2012022016411617633

You'll probably have to copy and paste it into your browser.

Jud
J K Chapin

I gather the unit is a parallel thread, not tapered.

Thankyou to those who so far have given answers to my query.

Rob
Rob Grantham

Has anyone determined the correct size?

Tom Lange
MGT Repair
t lange

Here is a someone on ebay selling replacements. Maybe he would respond to what the thread size is:

https://www.ebay.com/itm/167312990017
Christopher Couper

I see in the archives that Butch Taras uses 1-5/32x13, and he ought to know!

Tom Lange
MGT Repair
t lange

Roger Furneaux, whom I trust, informs me the thread is 3x20mm.

Tom Lange
MGT Repair
t lange

I think it is 1/2" BSP same as the sump plug.
I don't see them making it when they could buy from stock. See the off the shelf axle fill and drain plugs.
British pipe thread is notated by nominal pipe bore.
Only a British car would have BSF,BSP,BS brass,BS cycle,BA , Unified and mad metric on the same car
Oh and ONE BSW (the dynamo adjustment)
Ray TF 2884
Ray Lee

This thread was discussed between 27/11/2025 and 04/12/2025

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