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 MGB Technical - Rear Axle removal to replace seal

I have a 72B w/steel wheels, tubed axle. I assume I have a right rear wheel gear lube leak, I assume it is the seal at Hub that is leaking. The back of the brake backing plate is very greasy, top to bottom.

A year or so ago (yes, I sure get to these things promptly) I had the right rear drum off to make sure the wheel cyclinder wasn't leaking. I pulled rubber boots off and no fluid leaked out. I sanded down shoes a bit to lightly clean them, but they weren't soaked with oil, I topped off the rear end; and waited for an opportunity to fix seal leak.

So...

I'm about to pull the right axle out to access inner seal, but want to have all my parts on hand first and be aware of any pitfalls ahead.

I have the seal, new brake shoes, and I plan to turn the drums, and I plan to remove the access plate on back of diffential (I have this gasket too) to just look at things, clean gunk out-make sure vent in axle is clear and eventually refill with Valvoliine synthetic gear lube.

Someone has pointed out that when removing the rear wheel, drum, brakes, hub, axel, etc., I will need to remove bearing and to get bearing out it may become damaged, so I'm going to buy 1 bearing at this time.

In looking at Moss catalog for axle I don't see another gasket that I thought would go somewhere between hub and perhaps the hub bearing cap.

1. Is there another gasket between the brakes and axle?
2. Does the seal between the hub and the bearing serve as the only seal to gear lube leaving the right axle and getting to the brakes or exiting the rear-end?
3. Are there any pitfalls I haven't considered?

Thanks.
R.W Anderson

1 No gasket fitted.
2 Yes it"s the only seal
3 It is not necessary to remove the shaft and it"s bearing. It is quite possible and indeed preferable to leave the shaft and bearing undisturbed. (Assuming the bearing has no play in it) simply remove the four bolts push the brake back plate gently to one side, remove the cone from the drive shaft and lever the oil seal out of the bearing retaining plate. Thoroughly clean the entrance to the hole, lubricate the outside of the seal and press it in with your fingers. If you prefer just tap the bearing plate to loosen and do the job on the bench. Clean faces are essential, reassemble with a smear of Hylomar or similar jointing compound. Jim
jim soutar

Do this job with the axle on the car.
The torque for the hub nut is very high so you need the axle to be on the car so that the car "holds" the axle while you try to turn the nut. Scafold tube on the end of my socket driver normally does it.
David Witham

The differential takes differential oil, not gear oil of the type that goes in the gearboxes of V8s, so make sure you use the right stuff.

1 and 2 are no and yes as above.

The hub nut is torqued to 150ftlb and then to the next split-pin hole. Attack this with the wheel hub cap off and the wheel back on the hub and the tyre on the ground. Both nuts are normal i.e. right-hand thread, 1 5/16" AF socket (same as for the crank pulley nut), remove the split-pin. If you use a socket extension bar rest the outer end on a support on the ground i.e. piece of timber to keep the forces square to the axle shaft, although this is probably more important with wire wheel hubs.

The hub can be stuck on the taper on the half-shaft, I have shifted this with steel wedges between the heads of the back-plate bolts and the back of the hub, tapping first one side then the other.

With the hub and backplate off you should be able to tap the bearing cap complete with oil seal off leaving the half-shaft and bearing in the casing. Look for the join between the cap and axle casting and use a sharp chisel in that gap, tapping in two or three places around the circumference. Alternatively you can loosely refit the hub and tap on the back of that with a mallet in a couple of places to *start* pulling the half-shaft and bearing out of the casing, and that will open up a gap between cap and axle, which will allow you to tap the cap off the bearing with a blunt chisel. When retightening the back-plate bolts it will pull it all back together again.

The oil seal runs on a collar (the cone that Jim mentions) that slips onto the end of the half-shaft, with a parallel face that the oil seal runs on and a tapered face the hub bolts up to. If that parallel face is in any way damaged or grooved replacing the oil seal almost certainly won't be enough, and that collar should be replaced as well.

Grease the new oil seal (filling the groove that faces into the axle, the flat face faces out) and collar, even though the seal runs in oil when on the road.
Paul Hunt 2010

So if I already have a seal, there appears no need to buy a new bearing, as the bearing in place shouldn't be damaged by replacing the seal, and there is no rubber oil ring or other gasket in this area.

I'd refill with valvoline synthetic 70-90 or whatever it is that is close to that.

I still want to pull cover off rearend/differential to see how things look while I'm at it, and clean out any gunk that may be in there, oh and any little metal parts.

Does someone wish to estimate time, allowing for cussing at not having enough leverage to break nut loose?
R.W Anderson

Maybe half a day if all goes well. Not sure you will see much (short of bits lying in the bottom) with the rear cover off. If it runs well otherwise then you might do more harm than good.
Paul Hunt 2010

This thread was discussed between 29/04/2010 and 03/05/2010

MG MGB Technical index

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