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MG Midget and Sprite Technical - Oil seal back axle

Hi guys, I have a couple of studs come loose on the rear and when taking apart I have oil leaking on to brake shoes, I think it is a double bearing hub does it use a different oil seal to normal as I'm not sure what to buy? many thanks in advance for advice Howie.
HJ Cottrell

Can you clarify all that? Which studs came loose? Are you sure the oil came from the oil seal, and not from the halfshaft flange/gasket/o-ring?

There's only one bearing in the hub. To replace the oil seal in the hub, you have to remove the bearing.

Buy a kit from Sussex. Comes complete with oil seal, bearing and half shaft gasket/o-ring.

http://www.sussexclassiccar.co.uk/shop_factory_hazel/contents/en-uk/d689_01.html

HUB BEARING KIT REAR S+M
£9.24 (Inc V.A.T)
GHK1143
REAR HUB - BEARING KIT - midget

But make sure you need it before you buy it.
Lawrence Slater

if it's a double bearing hub then call Peter May for advice. Or carefully extract the old oil seal and pop in to your nearest industrial bearing supplier and have them match it.
David Smith

HJ: if your hub is standard there is only one bearing with a lipseal on the inner side.
The tube of the axle casing will have oil from the diff in it and if the break the seal between he halfshalf flange and the oil will run out....... all over the brake linings.
Once you have removed the brake drum there isn't much holding the half shaft in place (just one small screw) and you are relying on an o-ring and a paper gasket to keep the oil off the linings.
Graeme Williams

As Lawrence says there is only one bearing in the hub but he forgets to mention for single bearing hubs only because if, as you suggest, your car has double bearing hubs it will have 2 bearings. Lawrence - there are books with this stuff in.

As far as I know all the double bearing hubs are supplied with a grease seal at the rear rather than a proper oil seal. However, if you can post a photo of the back of your hub and a measurement of the seal I can give you a part number for an oil seal (assuming it's the same double bearing hub everyone else has). On the other hand there is a book with this stuff in so maybe someone can look it up and post the part number!
Daniel Stapleton

If the leak occurred when you were replacing the wheel studs, then it seems likely that it is between the halfshaft flange and the hub, rather than from behind the bearing. Paper washer and O ring will fix that.

If it is the bearing, I recall reading somewhere (may be in the archives, I don't go there) the single bearings can be replaced specifying an oil sealed bearing which in effect does away with the need for the normal inner one. Or at least doubles up and reinforces the normal oil seal effect. Maybe the inner bearing for a double bearing hub can be similarly specified?

Inner ones may leak even when replaced with new if the axle end has become scored - in which case a speedisleve can be fitted to provide a fresh new surface.

When working on the rear hubs, if you jack one side up to a reasonable working height, the oil drains back down the axle tube and you don't get any spillage as you remove the hub and halfshaft parts.
Guy W

Thanks guys, There is a small amount of oil on the brake shoes, the wheel studs have stripped in the hub. I have got the wheel and drum off. Not got any further yet. Just remember when I bought the axle from J P ivey(I think) many years ago he said it had a double bearing kit fitted so that's why I wondered if it had difference seals. Cheers Howie
HJ Cottrell

Guy: when I replaced my rear hub bearings I specified metal shielded (this may be "ZZ") which is what was suggested in a tech article somewhere. THis keeps the grease in the bearing but there is still the oil from the diff working it's way through/round the bearing possibly. I wouldn't want to leave out the lip seal. You can't beat belt and braces!

I haven't come across double bearings at the back. Is that a common mod?
Graeme Williams

Graeme,

I usually post comments and advice based only on my actual experience, rather than what I have read. Or make it clear when posting a personal opinion or theory. But on this occasion I was going by memory of what I had read somewhere, as I explained.

I have had a look for the source and found it on the Chicagoland MG site. http://tinyurl.com/qb7xx6m

Quote: "When replacing the bearing, use a 207-FF (double sealed bearing, which then acts as a supplemental seal against axle oil leak). - Note the reference to it being a supplemental seal

Credited to the Author, Norm Kerr, who often posts messages here so he may yet appear to comment on this.

From Howie's explanation, I would still guess the leak is from the halfshaft flange, rather than the bearing
Guy W

Guy: I think we are agreeing on this. We both are saying the same thing although I ref ZZ rather than FF. I can't remember all the ins and outs of bearing shielding codes and I don't think it's standardised between makes anyway. Either steel or plastic shielding would serve the purpose. With SKF the steel shielding is coded ZZ according to my original invoice.
That shield should prevent the diff oil getting thro, but why risk it and leave out a lip seal costing less than £3.
Graeme Williams

Yes, I thought we were too. Just taking the opportunity to update with the source of my info, since I had tracked it down. I too was taking the reference to this being a supplemental seal as meaning to use the original design one in addition.
Guy W

I think if you use the bearings with rubber seals, sometimes a 2RS suffix, you could do away with the lip seal, it would need a good greasing as it wouldn't see any additional lubrication if fitted. With shielded bearings the lip seal should be retained as the shields do allow some flow of oil past them.

Years ago I read an article on gearbox design and it stated that gearbox designers found that bearings based on the design parameters and loads didn't last as long as anticipated so they had to use larger bearings. It was found that the shorter bearing life was due to debris in the gearbox oil damaging the bearings and the fitting of shielded bearings prevented the passage of debris into the bearings but allowed a slow transfer of oil through the bearings so allowing the as designed bearing size to be used. When I read the article I immediately thought that the gearbox designers referred to had never dismantled a used gearbox and seen how much crap there could be in the way of metallic debris present, fortunately the harder steel debris is often caught by a magnet but not all boxes have them fitted as standard.
David Billington

This thread was discussed between 29/08/2013 and 30/08/2013

MG Midget and Sprite Technical index

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