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MG Midget and Sprite Technical - Track Rod Ends Tread Size

I have lost one of the nuts that secures the taper on the track rod ends on my Sprite. My collection of old and new nuts and bolts goes back for 30 years and I can't find anything to suit. The Welsh MG Centre were helpful and sent me two nuts but they are too small. The size of the thread on the taper is 0.753" x 20 TPI. This suggests a UNF but 1/2" is too big and 7/16" is too small. I know track rod ends are inexpensive but the ones on my car are virtually new. Can anyone advise on what the thread is?

Jan T
J Targosz

The thread on the taper of my track rod ends is 7/16" UNF. Is the 0.753" dimension correct as that's larger than the hole in the steering arm.
David Billington

Some use metric, 1mm thread (M10 if metric). Well modern Borg & Beck and Front Line do (Borg & Beck is Front Line).

I have two Borg & Beck TRE in front of me now but if you check the Archives for M10 1mm thread you'll see how I know.

Boots lasted 7 years on my present Front Line TREs.
Nigel Atkins

That's First Line, not Front Line, must be seeing David's name that's reminds me of them ...
Nigel Atkins

I think the later (‘72-on) TREs are metric, these days. Im not sure if they’ve always been that way, or whether it’s modern replacements.

The size of the hole in the steering arms also changed for the later rack.
Dave O'Neill 2

My fault I should have said the diameter of the thread above the taper is .471" x 20 TPI. 7/16 is .037 hence my confusion.

Jan T
J Targosz

Is it M12 x 1.25 fine? If it has been metrificated.

0.471" = 11.96mm, 20 TPI = 1.27 mm pitch. Those are both damn close.

No UNF threads tie up correctly.

Malc.
Malcolm

Jan,
as you've not got a 'Vehicle profile' to view I forgot (IIRC) you have a 1966(?) so that would normally have the Morris Minor type steering rack whereas mine is a later car with Triumph type rack so does have different TREs.

I can remember being surprised I needed a metric spanner (17mm) on the TRE nut but not when that first was.

It would perhaps make sense that if yours a re First Line / Borg & Borg that might also have a metric thread and nut/spanner fit but who knows, I think I've heard of metric spanner size nuts with imperial threads, it's a mixed up, muddled up, shook up world, except for Lola.
Nigel Atkins

Malc,
on the First Line and now Borg & Beck TREs that I got for my Triumph type rack the nuts are metric M10 x 1mm. I know as I previous asked a friend to pick up for me M10 nuts in 1mm, 1.25mm and 1.5mm to be sure I had the correct thread as the matter was confusing at the time.

I've found the original thread 'Triumph style TRE nut thread and size please'.

Just to make things even more confusing the (First Line) Borg & Beck online catalogue states a wrong thread for the item, I've found this also on one of their oil filters and was exchanging emails with a top guy as he monitored emails coming in to his managers and he said he used to work on the line so knew the thread stated was wrong, but it didn't change when I look on the site a month later.

The Borg & Beck has "THREAD SIZE 1/2"x20 - THREAD TYPE with right-hand thread; with internal thread; UNF Thread" this is NOT so with the ones I have, a M10 x 1mm fits but a 3/8" UNF doesn't.

Borg & Beck BTR4072 - https://webcat.firstline.co.uk/PartDetails/BTR4072/#partInfoBTR4072

First Line FTR4072 - https://webcat.firstline.co.uk/PartDetails/FTR4072/#partInfoFTR4072
Nigel Atkins

Nigel

I think the 1/2"x20 refers to the internal thread for the track rod.
Dave O'Neill 2

Dave,
doh!

Thanks, reading too quick and association with previous half inch, now you've pointed it out it's obvious, 1/2" thread should have been a clue! :)

The 'Buyer's Guide' section still suggests it'll fit a "midget (1966-1973)" and the thread for the previously mentioned oil filters was wrong too.

And the TREs I have come with M10 x 1mm (nyloc) nuts so I've got those right - thread I was talking bollocks again. I was beginning to wonder if I can actually do and think about two things at once and came to the conclusion I could - but get both wrong! :)
Nigel Atkins

This thread was discussed between 28/06/2021 and 29/06/2021

MG Midget and Sprite Technical index

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