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MG MGB Technical - rear axle oil leak

Last year the roadster failed its MOT on rear brakes, on inspection oil was coming out past the oilseals on the axle. fitted new oilseals, rebuilt the brakes. This year it has failed again on rear brakes (low on one side) on inspection oil is still coming from the axle past the oilseal. Am I correct in thinking there is away the half shaft has to be centralised before tightening to the axle.
Trev
Trevor Harvey

Axle type?

The Salisbury axle oil seal runs on a replaceable collar (AAA982 from all the usual suspects), it's quite possible that is damaged. They should be inspected for any grooving or wear marks when replacing the seals, and replaced is necessary. It's the bearings that centralise the half-shaft, both ends, and I can't imagine the bearings being so worn that excessive movement is causing a new seal to leak, without other very obvious signs of problems.

The other thing is to check the axle breather is clear, otherwise pressure from heat build-up can blow oil past the seals. This is on top of the axle on the right-hand tube, a plastic screw-in fitting, 1H 3364.
Paul Hunt

If it is an early roadster with the banjo axle, check the fit of the wheel bearing in the hub. It should be a press fit. Movement there, or in the bearing itself, causes oil to leak past the seal.
Wear usually arise from insufficient axial nip on the bearing, so it pays to put a bit of effort into checking it and making sure it is right. I aim at a thou of interference fit by the time the gasket is compressed.
Paul Walbran

Thanks for your advice. Its a 71 roadster so I assume its the later Salisbury axle. I will fit another oilseal and breather and have a good look at the collar.
Trev
Trevor Harvey

On inspection the collar has a very slight groove on it where the oilseal runs so I have ordered a replacement of both.
What should the nut on the end of the halfshaft be torqued up to. Thanks. Trev
Trevor Harvey

Trevor, From memory torque between 40 and 70 ft/lbs. The variation is to allow for alignment of the split pin holes and slot nuts. Also do a 12 and 6 o'clock rock on the wheel. Any play will indicate wear on the inner dif, half shaft gear, bearing surface which would speed up seal wear.
Allan Reeling

40 to 70 is the front hub nut. The halfshaft nut is 150 lb/ft
Paul Walbran

Neither of the halfshaft nuts were tightened to 150. Would this have contributed to the oil leak.
Trevor Harvey

The hub is tightened onto the taper on the collar, which pushes that against the inner part of the bearing on the half shaft. If they were 'loose' then it's possible oil was seeping out from between the collar and the half-shaft, rather than from the oil-seal itself.
Paul Hunt

AS I SAID PAUL...............MEMORY..................NOW WHAT WAS THE QUESTION?????
Allan Reeling

Sorry, I can't remember either!
Paul Walbran

This thread was discussed between 09/11/2014 and 12/11/2014

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