MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - Oil leak from rear axle hub

1958 1500 MGA, stock, wire wheels, #52353, coming out of perpetual restoration.

I have significant oil in the left rear brake drum. It's coming from the paper gasket where the wire wheel axle hub mates with the wheel hub. When I pulled the axle significant oil dribbled out. I'm assuming I need to replace the hub's oil seal and I'm trying to gauge whether the job is beyond my capabilities.

I have the Workshop and a Haynes Manual and I've reviewed both. I'm looking for input and suggestions from those that have done this job.

First, what size is the axle nut and what is used to remove it? A stilson pipe wrench seems like a sloppy way to get the job done.

I have a spare hub on which I have removed the bearing, so I can install the oil seal and bearing into it without removing the one on the car. If this doesn't go well I can stop here and still have the car be mobile. Suggestions on how to make this easy and correct would be appreciated.

I know the hub is removed from the axle housing with a puller. To reinstall how do I know if it's seated correctly and how does oil from the axle housing not leak out where the hub meets the housing? I realize this question / concern is a little fuzzy but I haven't gotten to this point yet. I'd be committed to the task if I take it this far and therefore unable to get the car to a professional.

Any input to my specific concerns or any other offerings are as always appreciated.

Thank you for taking the time to review my problem.

Brian Denis
Brian Denis

Where are you in Mass Brian? Im in Woburn.
S

Barney Gaylord has unbelievably documented many fixes...heres his site...and you have some reading to do!

Here you go!

http://mgaguru.com/mgtech/rearaxle/ra1.htm
S

Brian

This was a problem from day 1 with MGAs. One change that was made by MG was to drop the oil level in the diff from 2 3/4 to 2.0 pints. You still filled to hole but it was lowered. If you have one of the earlier diffs with higher fill hole just drain and measure the replacement oil to 2.0 pints. My pints are UK not US. I just happen to have replaced my diff oil this week. This action by MG was more avoiding the worst of a problem rather than a fix!

Also I don't think early ones had the O ring but I think this change was before your car. All this is probably on Barney's site.

Paul
Paul Dean

Paul -- I would be delighted to know where you may find the information that MG ever changed the specification for oil level or volume in the MGA rear axle. Specification for capacity in the Workshop Manual never changed. The Service Parts List retains same part number(s) for the axle housing all through production, so the fill plug location never changed.

There was one service bulletin from "THE AUSTIN MOTOR CO. (CANADA) LTD." / "MORRIS MOTORS (CANADA) LTD." mentioning "Do not over-fill the axle but rather fill to about 1/4" below the level of the filler plug". See here: http://MGAguru.com/mgtech/rearaxle/ra101a.htm

I'm not sure if 1/4" low translates to that much reduction of volume. This is a generic memo applying to all Austin rear axle assemblies (A, B,and C series), not specific to MG. As far as I know MG never issued such a memo.


Barney Gaylord

Steve, I'm in Newburyport. More specifically restoring this car for 10 years +/- in my driveway without the luxury of a garage. It's still not on the road, but my ETA is next summer.

Last PM I reviewed Barney's as usual comprehensive information. More thorough reading is required before I push ahead. From Barney's site I've already learned the size of the axle nut (and found the socket for sale from Moss) and the suggestion about chilling the bearing hub before installation. As always Barney, good stuff.

Paul, I've got one dry wheel and one that's not. So I have to address the leaking one. I will check the fill spec if/when I get there.

My current plan is to refurbish my spare hub and if I'm confident purchase the Moss socket and move ahead.

Thanks for the help so far. Any other suggestions are most welcome.

Brian Denis
Brian Denis

Just recently done that job Brian.
There are two different seals. THe most common failures are with the outer seal which is a paper gasket and on the Mk2 there is a large o-ring too. I don't know whether the o-ring applies to all models. These can be replaced by pulling the halfshaft. If you jack up that side of the car, excess oil will run back down the axle tube to the lower end and so should reduce spillage when you pull the half shaft. Or drain te diff. Just make sure you have enough room between the car and the wall to get the shaft out, and watch out for oil getting onto the shoes.(no. not yours, the car's!).

These outer seals do not need the hub to be touched at all other than scraping the mating surface.

The other seal is a lip seal which fits on the inner side of the hub and needs the hub to be removed to change it. However, if you look carefully you should be able to determine from where the oil is spread, whether it is the outer side (easy) or inner seal (pita). From my experience with Sprites too, the outer seals are the favourite to leak because when you take the wheel off, the main clamping pressure on the seal is removed (leaving one or two small screws to do the job) and the leak starts and then retightening doesn't stop it.

Replacing the bearing when you do the inner seal is not a bad idea if there is any doubt about it. I put mine in the freezer (as suggested) and it slipped in a treat. It isn't a cheap bearing (at least not in a decent make and in the uk).

The most difficult part of the whole job is making sure you have the right box spanner (with 8 flats!) although I think someone else will tell you how to do it with a standard socket. Best not to use a chisel or plumber's tools. Oh, and remember one side has a left hand thread.

Graeme Williams

Graeme, thanks for the input and you got me thinking.

How much oil is supposed to get by the hub/bearing oil seal (Moss part 120-900) and to the bearings? I've been assuming little to done.

I could easily replace the o-ring and paper gasket but I expected that would only hold back the tide for awhile. My track record when I do a half butt job is lousy, but I suppose I could try doing just the paper gasket and o-ring and see what happens.... unless someone with superior experience knows this won't work.

Again I appreciate the time spent reviewing my problem.

Brian Denis

Brian Denis

There should be no signs of oil leaking passed the seals Brian. The problem is that it can get onto the braking surfaces.

The outer seals in my experience seem to leak at the slightest disturbance. I normally buy three or four of the gaskets and o rings at the same time, if only because, in the uk at least, postage is more than the cost of one seal and ring.

I have probably replaced the outer seals on the A and on my sprites half a dozen times. The only time I have replaced the inner lip seal was when I have stripped the hub to replace the bearings.

The problem with the lip seal is you have to remove the bearing to get at the seal, and the seal prevents you getting access to the outer race to knock the bearing out correctly. I feel working on the inner race to force out a bearing which has a drive fit on the outer race will lead to damage and therefore will require replacement anyway.

Not difficult jobs.
Graeme Williams

Barney
The source I checked before writing my entry above is Piet Olysager's Sunday Times Motor Manual for the MGA published in 1963. it says 2 3/4 imp pints for 1500s and 2.0 for 1600s and 1600 Mk 2s.

Like you I am very long term/very high mileage MGA owner, from 1969/around 250k miles, so there are things I learnt years ago where I find it difficult recalling the source. I think the story that MG did it to limit the problem rather than fix it completely goes into this category, but I might remember the source in due course.

I am less sure on the O rings if they weren't there originally as I think when did they come. My 2 1958 axles certainly have the rings.

Paul
Paul Dean

WSM Sec H.10 -- O-ring seal added to bearing hubs; (axle)3725 for disc wheels; (axle)5225 for disc wheels; (Date uncertain. Not in SPL Jun-56, but is in SPL May-57)
Barney Gaylord

Brian
If you need anything for your car let me know I had a couple of parts cars a few years back. I'm going to start ebaying off the extras soon.

I need some space back and I don't think Ill need all these extras.

It took me 10 years to get my car back together too. I'm lucky to have a garage
S

About oil in the bearing hub, .... there is a flow system. Oil flung from the ring gear is caught in a trough high in the axle housing. From there it runs downhill (outboard) by gravity until it flows into the rotating bearing hub. The hub fills with oil (about 35%) until it will flow back into the axle housing, and from there back to the differential.

So, while running the hub will be about 1/3 full of oil,and it keeps circulating. The inboard oil seal is therefor partially submerged in oil, and any small leak will soon look like a big leak.

If/when you pull the halfshaft out, you break the seal on the hub, and an ounce or two of oil will drain out of the hub.
Barney Gaylord

Barney

Me again. Interestingly my official WSM lists the different oil capacities for 1500 and 1600 as I quoted but in text just quotes 2 3/4. My WSM is AKD600B. I am not surprised about them not showing a different part number as presumably after the change they just shipped the later. As you know there are other examples of undocumented changes, inlet manifold is one.

I suppose in reality most people just fill up and don't know quite how much they put in as it is rather awkward. I have never worked out how you are supposed to check the level as specified as a service item.

As I believe it was achieved by lowering the filler on the crankcase it would be interesting to compare a 1500 one with a 1600 one.

Another point is I have 2 period third party manuals that also cover MGBs and they just quote 2 1/4 imp pints which I presume is the figure for early Bs?

Paul
Paul Dean

As I am currently driving about 40,000 miles per year, I drain and refill the rear axle a couple of times per year. If I an conscientious about it, I may leave oil level one knuckle below the filler hole. Otherwise I just fill until it runs out and call it good. With Speedy-Sleeves and fresh hub seals it doesn't leak.
Barney Gaylord

I've learned something from every poster to my problem and I thank you all.

I was under the assumption that the inner seal kept oil out of the bearing hub and the only lubrication for the bearings was grease. Since I now know that oil is supposed to be there I can confidently replace the o-ring and paper gasket, but not the inner seal, and feel like I'm taking care of the problem and not doing a half-butt job.

Steve, I think I'm good on major parts. I'm at the stage of restoration where I'm ordering the right gaskets, nuts & bolts and assorted shiny bits. I've been a lurking member of the Bay State MGA Club for several years. Hopefully next summer with a running car I will be more involved.

Brian Denis
Brian Denis

This thread was discussed between 26/08/2016 and 28/08/2016

MG MGA index

This thread is from the archives. Join the live MG MGA BBS now