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MG MGA - Damn! - Rear axle hub leak again

Well this weekend I went for a 200mile drive down to the keys...very nice indeed.

Unfortunately to my suprise today I realised there is still a real axle lead on my right rear wheel. If you remember I wrote a report recently on the work. Basically changed the hub seal, installed a speedi-sleeve and changed the hub.

I have not taken the drum brake off but I it is coming out from inside so I suspect the seal is not working as it should...

Has any of you suffered something similar?
I am wondering if I didn't push the seal in enough? In fact it was the guy at the workshop who pressed out/in the bearing who did it, and he just did it with is thumbs....
I am pretty sure he put it in the right way too, with the flat face of the seal first.

Otherwise I wonder where the speedi-sleeve is not correctly installed, although I made sure it is flush with the chamfer of the axel and ensure it didn't get scratched during the work.

I was hoping the done was complete and would not have to mess with that again but as you see this is not the case.
I juat wanted to get some of your ideas/views so I know what I should look for when I take it apart again.
Gonzalo Ramos

If the rubber seal leaks, the oil is supposed to be dribbled into a flanged area of the ID of the backing plate. It should then run down the inboard side of the backing plate and end up on the wheel rim and inboard sidewall of the tire.

If you have oil inside the brake drum, dribbling out around the perimeter of the brake drum (and wetting the brake linings), then it is more likely a leak at the o-ring and paper gasket joint between the outboard and inboard hub parts (easier to fix).
Barney Gaylord

Barney, You say -- "If you have oil inside the brake drum..."
Could that indicate over filling of the diff?
Barry Gannon

Is the breather in the rear axle housing clear?

M F Anderson

""I am pretty sure he put it in the right way too, with the flat face of the seal first.""

If I understand you correctly then this seal is in back to front?
Bob Turbo Midget England

I am a bit confused here.
In the attached diagram the oil is moving left to right as it meets the seal.
Therefore the lip of the seal should be to the left, the flat face of the seal is pushed into the hub "flat face first".
A long time since I did one of these. Is that correct?


M F Anderson

Everything I understand about lip type oil seals is that the side with the spring should face the oil. So in this case shouldn't the flat face of the seal be towards the outside of the car?

David Ahrendt

Bob, Mick, David,
Yep, the side of the seal with the spring should face the oil. In this case the flat face of the seal should be towards the backplate.
C Manley

Now you are talking about the 'over filling'.
I did add some oil into the differential after performing the job, as I figured it would be low. I added about 1/2 pint.

I also checked the breather plug and it is clear.

Barney, I understand what you mean about the oil dribbling inboard or inside the drum. I will have to open it to check, but I remember last time I had it opened, I looked for this 'flanged area' of the drum backing plate but could not find it (maybe it is full of muck?)

Regarding the seal, in response to David the 'spring' is facing the oil (outboard), as the oil comes though the bearing. Hence the flat face of the Hub-seal goes 'inboard'. That is how I installed it.

If it is the paper gasket and O-ring which are at fault, I will check them, but I am not sure I can do anything else to improve the seal...
I change both for new ones; and clean properly both mating surfaces.
I put the O-ring on the Hub lip before installing it, hoping that would seal correctly (That is how the old one was installed).

I guess next weekend will be another one with Oily-hands!
Gonzalo Ramos

I had some trouble with that in the first few years after the restoration was finished. You might try some liquid gasket on the paper seal. My 1500 is a fairly early one and only has the paper and no
O ring. Just make sure it is a hardening type liquid gasket, since I found out the hard way that the, I believe it is called Hypomar and is blue, non hardening type will
fly out after driving at high speed due to centrifical force, and it sticks your brake shoes to the drum really nicely! After a clean up I realized that I may be overfilling the axle. With the car level If you can feel the oil with your baby finger stuck in the fill hole that is the right level. I used to squeeze in some extra until some began to run out of the filler hole and quickly put the plug in. More is better, right? Wrong. I think that was the main problem in the first place since the leak has never returned. My theory is that with more oil it tends to run out more heavily to the outer ends of the axle, and with the paper gaskets you just have a greater chance of a leak. You pack the outer bearings with grease anyway when you install them, so they really don't need axle lube. Maybe others have a different opinion. Interstingly, mine was the right rear wheel side that leaked also.
Good Luck,

Yes I agree the flat face of the seal faces the backplate, I misunderstood your explanation the oil comes from the outside through the bearing and is then retained by the seal inboard of the bearing.
Robert (Bob) Midget Turbo

I also had a couple of goes at fixing an oil leak on the right hand side rear axle by just changing the oil seal. Eventually I install a Speedi sleeve, new seal, bearing, o ring and paper washer (a dab of Loctite No 3 gasket sealant)- problem solved (I assume your bearing is in good condition). I use a spray pack of brake cleaner with the small tube attachment to clean the back plate and witness hole. Also I am running Penrite 85W-140 oil in my diff. on the advice of my diff rebuilder - this may help a little.
Mike Ellsmore

I did the same as you Mike, changed the internal seal, speedi-sleeve, o-ring & paper gasket, but I did not change the bearing as it seems to be in good condition.

Could you explain where you put in the Loctite sealant? In between the faces where the paper washer goes or around the O-ring?

I also used Brake cleaner to clean all the oil and gunge from the brakes, however, what do you mean by 'Witness hole'?

BTW I added regular 'Gear Oil 85W-90', I hope that is ok. I read some stuff somewhere about dangers of 'hypoid oils' in this application.

I understand that the 85W-140 is much more viscous so the chances that it runs out through the seals are less?
Gonzalo Ramos

Gonzalo, make sure that the Speedi sleeve has been positioned correctly and that the seal is running on it. Also the sleeve should have some sealant underneath it, next to the old seal face.
Art Pearse

Gonzalo, you should use Hypoid in the rear axle.

It's only recommended to not use it in MGA transmissions.
John DeWolf

I will check the position of the speedi sleeve, but I it is difficult to see where the seal is running once installed. I could definitely feel the resistance of the seal on the shaft once installed by rotating the hub.

I used 500degF gasket sealer inside the speedi-sleve to seal against the old seal face. Hopefully that part I did right.
Gonzalo Ramos

Hi Gonzales

There's a little drain hole in the square flange that the backplate bolts onto. It's at the bottom when the axle is in the car. It's usually full of crud - old oil, brake dust and rust. It comes up to the radiused area of the axle housing where the seal runs, and is hidden by the rotating hub when everything is assembled. You may be able to detect it from under the car, just run a drill bit up it by hand to clear it out.
dominic clancy

Last weekend I got around fixing the oil leak.
As Sir Barney Gaylord suggested it was a leak around the paper gasket and not the inner hub seal. Thank god for that!
I put a blob of gasket sealer (Pro-Seal - RTV Silicone - the red stuff) around the O-ring and mating flange, put it together, removed the excess and tightened the nuts. I hope I didn't put too much that could run into the bearing!

BTW anyone can tell me if the paper gasket should be installed dry or oiled? When I too mine off, the paper was mostly still dry (i.e. no oil coming out from the O-ring seal, except around one of the hub bolts.
I figures it would get oily soon so I oiled the surface.

I will see with time what happens.

I also 'discovered' the drain hole as Dominic suggested, and it was completely plugged with muck.

Thanks guys for the help!

P.s. Now I need to do the other side! ;0
Gonzalo Ramos

Early cars had only the paper gasket, and it didn't seal very well. When the o-ring was added the paper gasket was retained as a distance spacer, as it affects side clamping of the bearing outer race. Paper gasket must be the correct thickness. With o-ring in place the paper gasket does not need to seal, just serves as a spacer and parting agent for easy disassembly.

When tightening things up, tighten the flat head screw on the half shaft flange first. Align access hole in the brake drum with that first flat head screw, screw down the brake drum, then tighten the first screw again. The outer screws or nuts will pull the assembly up tight. Re-tightening the first screw afterward will assure the o-ring joint stays sealed when you later remove the brake drum.
Barney Gaylord

I am reassured Barney, this is what I did.
I would like to add though that it would better design to have at least 2 of these Philips screws to have a symmetric pull. With only one, the hub is pulled slightly more from one side. Just being picky.

I must say however the paper gasket I got from SF is rather thin. I have the impression that the one that came of was thicker, or may have expanded over 20years with the oil.
Gonzalo Ramos

The paper gaskets ARE thin. Do NOT install a thicker gasket, as you would lose the clamping grip on the outer bearing race.
Barney Gaylord

Yes Sir!
I going to do the other side tonight! Then I will have had enough 'hubs, gaskets and diff oil for while.
Gonzalo Ramos

Did the other side fine last nite.
Checked the RH again and the Oil seems to be slightly seeping again... This time it looks like it is coming out of the holes where the bolts go into.
Somehow the O-ring is not sealing right.

I am thinking I should probably let the sealant set before I push in and tighten the hub in fully.
Gonzalo Ramos

Third time going I re-sealed the hub 'O-ring' flange with with Permatex No1 sealant - Hardening this time.
It is like a brown paste, supposed to set hard.

Seemed better than the RTV silicone, but we will see with time if the seal stay.
This time I cleaned and degrease both side properly with Brake cleaner, but it is not an easy task with all the axle oil around...

50miles this weekend, no problems so far...

Gonzalo Ramos

This thread was discussed between 12/07/2010 and 26/07/2010

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