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Q & A: MGB Rear Ends

Hi John -

Not sure if you're using this email for technical assistance questions
but thought I'd ask. You've been very helpful in the past and I
appreciate it.

I own an early MGB (chassis #951) with the banjo style rear end.
Unfortunately, the rear axle oil level ran low due to leaking seals at
the wheels and the outer wheel bearings got hot. I mean very hot -
smoke was flowing out of the left hand wheel well. Preceding this, that
outer bearing had begun clicking.

Out with my wife on a Sunday drive, thought the clicking was a pebble in
the tire tread at first. Didn't want to call a tow truck with my wife
along and thought I could limp it home. Mistake and expensive miles.
Should have known better.

Anyway, locally someone knowledgeable about the early style of MGB rear
end said if it got that hot, not only are the bearings ruined but the
bearing housings in the axle casting are probably distorted and I'm
better off just finding a good used entire rear axle assembly and
substituting this one for my old.

He also suggested that I'd have an easier time finding a later style
(tube type) rear end and better chances that it would be in good shape
since it would be newer and the design was much stronger. My car has
disc wheels by the way, and I want to keep it this way.

I haven't taken my old rear end apart yet but fear the worse. Having
done a rear axle swop on a GT years ago, I know that it's not too much
work. Probably easier than tearing my old rear axle assembly apart,
sourcing seals, bearings etc, and reassembling. Perhaps still to have
problems.

Anyway, my questions are these:

1) Do you agree that it's probable that my car's rear axle tube
assemblies are ruined by the overheating? If you recommend that I tear
it down to see, what do I look for in those bearing housings. Also, I
only have a three eared gear puller style puller, can I pull the wheel
hub off with this or need a more specialized tool?

2) What sort of adaption challenge would using a later model rear axle
assembly entail? I seem to recall hearing that the drive shafts are
different but I'm not certain, and that maybe there's a clearance
problem with the original style gas tank on my car. Can this
substitution work?

3) If I decide to go with a used rear axle (newer or older style), what
are some inspection tips on finding a servicable unit w/o dissassembly?
I'd assume checking for free play in the half shaft ends at the wheel
hubs, looking for obvious leaks at the wheel ends & differential case
and trying to sense excessive backlash between the ring and pinion gear
set by rotating and reversing the axle ends quickly.

That's all I can think of but I do have a known good wire wheel rear end
in my garage from a GT. Can't use it since I don't want wires and it
may not fit anyway. But it gives me a test bench to try hand or machine
tool measurements that you'd suggest before I go looking at used parts.

Thanks for your advice and help with this complex set of questions.

Chas Wasser

Charles!

I would hunt for a the proper banjo style rear end. While the
Salisbury, Tubed, or "GT" differential is heavier construction, those early
ones "never" fail (well, there ARE excepti... read more