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MG MGB Technical - Rear Axle Nut - replacement size?

1977 MGB--DOES ANYONE KNOW THE ACTUAL NUT SPECS/SIZE?
My rear axle nuts will not come off. Seal is leaking. I've tried a 3' pry bar+200 lbs bouncing on end(me), a impact wrench...4 days of soaking with penetrating oil. I suspect they were put on with an impact wrench...10 brake jobs in my past, never had one like this! I've tried every suggestion from the MGExp forum. No joy, I'll be cutting the nuts off this week. (yes, the cotter pin is out).
I hate to pay $20+ from Moss for 2 castellated nuts with shipping. Hoping to go to NAPA or the like, and get the nut, but since they will be cut...I will need the size.
(I know the socket is 1 5/16, I have one).
Thank you.



Joe Walck

Side Note: On my replacement half-shafts on my TD, instead of using a castellated nut, they came with a nylon insert lock nut. Instructions were to torque normally. Anyone ever try a set? Worked great on the TD. I wouldn't try this until there is some B discussion...if it even warrants consideration.

Joe Walck

Joe - Did you try turning the nut in the opposite direction? Cheers - Dave
David DuBois

Sure did, they are stuck tight. No movement either way.

After more goggling, I found this info on the web as far as the nut goes...can anyone confirm? Alternate source?

NUT SLOTTED, 1 5/16", 1/2 SHAFT, af

p/n's BTA249; 125-670(moss); BTA249B
Joe Walck

Do you have access to oxy-acetylene torch, a little heat directed to the nut and your impact wrench should free up.
Mike
Mike Ellsmore

The later Salisbury/tube axle half-shaft nuts have a standard thread both sides. I couldn't shift one of mine either, took it to my local garage and he used a 5 ft bar on it. He insisted it was a left-hand thread, on the left-hand side of the car, and succeeded in tightening it a smidgen, then got it undone the correct way.

How are you trying? Is the axle still on the car? If so refit the wheel without the centre cap/spinner, and jack it down. You can get more purchase on it that way with the brakes and everything else resisting the turning of the axle. Use a scaffold pole over your breaker bar.

Those part numbers are correct.
Paul Hunt

I put car back on the ground yesterday, tried again. No joy...ps I'd already removed the drivers brake shoes due to leaking seal & cylinder, so can only block the wheels & 1st gear to keep it from moving. I'm borrowing a 3/4" impact today...1/2 drive one I borrowed before maybe good for lug nuts off, but my big nut just laughs at it.
I'll let you know this evening how it fairs.
Joe Walck

7/8 UNF from memory. If not, definitely a standard thread.
Usually need a 3/4 drive socket and jump on about 5' of pipe on the end of the bar with someone holding foot firmly on the brake.
But a good 3/4 drive air impact wrench should do it.
Paul Walbran

A good electric 3/4 drive did it in 2 seconds! It just laughed at the 1/2 drive.
Joe Walck

This thread was discussed between 16/03/2014 and 18/03/2014

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