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MG MGB Technical - Rear axle oil seal

1972 B
I'm getting axle oil on one of my rear wheels and wonder how big of a job it is to fit a new oil seal. i have heard that its a good idea to replace the bearing at the same time.
Any help greatly appreciated
Gerry Lodge

I did mine on a 72B last fall, the 1st thing to confirm is that you have the simplier of the two styles of axles "tubed" vs. "banjo". Tubed is simplier.

If memory serves me right, the tubed style has a simplier seal removal process as the seal (this is where the memory part kicks in or doesn't kick in correctly) can be pulled out without removing the axle.

The brakes come off to access the seal, but they may be oil soaked by now anyway.

But it is an easy enough job, especially when compared to the banjo style.

I really need to take photos of the process each time I do these things, so I can jog my own memory.

I hope I have this right.
R.W Anderson

Reasonably sure yours has the tube axle. I did the seals on my 80 LE and wasn't a big job. Mine doesn't have wire wheels. The axle doesn't have to be removed, but the hub needs to come off. It's a large castellated nut with cotter pin, 1 1/8th inch or thereabouts. Loosen it with the wheels on the ground before jacking up and removing. Whether or not you change the bearings is up to you. Inspect them and choose, but most likely will be OK. They're obviously getting lubricated.
Rick Penland

Tube axle is not that hard. Rick pointed out the castellated nut is a big un and a bugger to undo if you dont do it with the car's weight on it. I learned the hard way! there is an MG is born episode on doing the rear end so you might want to view it on utube etc. As far as bearings are concerned they should be replaced only if they are worn or you have the luxury of funds you don't need. They are very big ball bearing races and as long as they have been runnning in good clean oil and haven't been run dry they should be pretty good.
A J Ogilvie

Thanks for the help everybody.
So when i take the big castellated nut of, how much of the rear brakes nead to be dismantled ? Any special things to watch out for ?
Gerry Lodge

A 72 should definitely have the Salisbury/tube axle. The brake shoes and handbrake lever will have to come off and the four back-plate nuts and bolts removed. You *may* be able to lift the back-plate over the end of the axle, but it could fracture the brake pipe. But first undo the castellated nut with the wheel on and the tyre partly on the ground, i.e. wire-wheel spinner or Rostyle centre-cap removed, and you will probably need a breaker bar. Both sides are standard right-hand thread, socket is 1 5/16" AF. If you have wire wheels an impact or 3/4" drive may well not fit inside the hub, but a 1/2" standard socket should, as long as it is less than 1.863" diameter. With the nut loosened you will need to crack the taper between the hub and the oil-seal collar on the half-shaft, I did that with steel wedges between the back of the hub and the heads of two opposite back-plate nuts, other ways are to put an old drum on backwards and hit that with a mallet, but not a drum that is going back on the car, or a puller. With the hub off you can remove the four back-plate nuts and bolts and the back-plate, to reveal the axle end-plate. This is about 1/4"-3/8" thick and can be drifted off the outer part of the bearing which is retaining it. The bearing itself should stay in the axle. The oil seal sits in the end-cap and can now be removed. But look carefully at the tapered oil-seal collar on the end of the half-shaft, if that is grooved it must be replaced as well, or the new oil seal will leak. That just slides onto the end of the half-shaft, but may need a very thin drift. Fit the new seal with the flat side facing outwards. Grease the lip of the new seal before fitting it over the collar, even though it will be running in oil.

Unless the bearing is giving a rhythmic growling when under load there is little point in replacing it, it is much harder to get that off and back on the half-shaft than anything else so far.
PaulH Solihull

This thread was discussed between 09/03/2011 and 11/03/2011

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