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MG MGA - Diff Oil Seal

Hi Guys
I have an oil leak from the front of my diff, which I should have replaced when doing the rebuild. Is it possible to
(a) Remove the Universal joint flange and(b) Replace the seal without taking the back axle out from either under the car on ramps or through the battery area.
Thanks for any suggestions.
Brian
Brian Paddon

Yes, I have done this a number of times.

Undo the prop shaft from the diff flange and tie it up out of the way..

Use Stevie G's method of a bar attached to the flange and wedged to the floor to stop the flange turning. I find a single bar attached to the flange with just two nuts is more than adequate and gives more space to get at the diff input nut: see here for the idea
http://mgaguru.com/mgtech/tools/ts209.htm

You will need an air gun to loosen the diff nut, though a breaker bar may shift it, the available arc is not great for getting enough pressure to break it free. Use a gear puller to pull the flange, then it's just a case of pulling out the old seal, cleaning up the flange surface where the seal runs (maybe a speedisleeve) and reassembly.



Dominic Clancy

I would suggest that you mark the position of the nut relative to the pinion shaft prior to removal and tighten it to the same position.

Also, you may find it easier with the chassis supported on stands and the axle on full droop, allowing better access.
Dave O'Neill 2

You also have access by removal of the floor panel behind the seats.
Bill Haglan

Brian

As Dominic mentioned I made this tool for holding the flange: http://www.mgaroadster.co.uk/odds_and_sods.htm scroll down to 3rd item.

Welcome to borrow to save making one.

Steve
Steve Gyles

Brian,

I assume that you have read the Workshop Manual?
I note that it says that you should mark the rear flange of the propshaft and the flange of the pinion shaft and reassemble with those markings.
I wonder why. It can only be for balancing purpose but after nearly 60 years you must wonder if it is in the original position now.
Surely the propshaft would have been balanced by the manufacturer before delivery to MG. Were they supplied with the pinion flange fitted? I doubt it.
The most important thing is to align the universal joints correctly if the propshaft is separated at the spline.

Mick
M F Anderson

Mick

I've never bothered to mark the diff flange and prop and I've never had a problem.

What are you supposed to do when you change the diff?
Dave O'Neill 2

Dave

I agree. I cannot see a reason for it.
But why does the Workshop Manual say that it is "most important"?

Mick
M F Anderson

When I recently worked on the diff I had totally forgotten about the cover above the axle. Once I realised, access was so much easier. The only issue I can see with removing the pinion nut with the car on the floor is getting comfortable access to put in the welly that the pinion nut needs to be undone and retightened. It has a high torque setting!

Graeme Williams

That's why I mentioned the air gun. I find that moves the nut with nothing more than a lot of noise.

That and wheels are about the only reason to fire up the compressor these days.
Dominic Clancy

The only problem I found changing the oil seal in situ was lying at an angle underneath and getting it positioned square on to push into place. Took me quite some time.

I don't remember paying any attention toe the flange position when I put the 5-speed adapted prop shaft in place, nor when I put the 3.9 diff in. I expect the instructions in the manual were left-overs in the tech pub department from earlier cars when perhaps the prop shaft was balanced in situ?

Steve
Steve Gyles

This thread was discussed between 12/02/2017 and 14/02/2017

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