Rear hub confusion

[DickN]

I did an search find out about rear hub oil leaks. I found that:
1. the hub bearing is lubricated by the differential oil.
2. The paper gasket and O ring should stop the oil from leaking.
3. the oil seal (inside the hub) is to be placed with the open end towards the bearing.

What is the purpose of the oil seal if oil normally gets past it to lube the bearing?
Before I spend $40- $50 on a socket to remove the nut, Can I stop the leak by just replacing the gasket & O ring?

Thanks
Dick

 

[GregoryW]

The seal keeps the oil from leaking out through the back side, and the gasket/O ring take care of the outside. You'll see how the seal works after you pull the hub.
What's confusing you, and what you can't tell from looking at the pictures, is that the axle shaft passes through the bearing, but it's much smaller than the inner race, and the 2 don't touch. Oil is free to pass from the axle housing to the inside of the hub.

I was very impressed with the design after we blew one of the seals this summer. There was axle grease everywhere, but the brake shoes were high and dry.
The hub and brake backer plate are designed so that the leaking grease is slung off under the car through the backer plate, and away from the brake shoes.

The gasket is a bit of a mystery to me. It sure seems like the O ring would do the job all by itself. Does anybody know?

To answer your question, the leak is probably coming from the seal, as it is a wear item. The O ring doesn't see much action. Check the back side of the backer plate. If it's oily, it's the seal.

I didn't need a wrench to get the nut off. It was fairly loose (too loose), and held in place with a bent-over washer. Be aware that the nut on the left side has left-hand threads.

You'll probably need a press to remove/replace the bearing. The seal is a pain to remove because, as you noted, it's in there backwards, so you can't just hook it with a seal puller (screwdriver).

Greg

 

[57_BN4]

The grey painted hub nut remover socket commonly sold isn't hardened and mushes up upon the first use. If you have a club nearby see if you can get a loan of a communal one which has a pilot shaft that fits inside the axle hole and prevents the socket slipping off the nut. You'll need a two or three jaw puller too to remove the hub from the axle.

A bench vise and two big sockets is sufficient to remove and replace the bearing. Warm the hub with a propane torch to start it moving if it won't budge with moderate pressure. Too much pressure and the bearing will be damaged.

The oring and gasket setup is somewhat illogical in that the oring seals against the gasket. I think the oring was a later addition as the early BN1 hypoid axles don't have an oring, just a gasket. Presumably when the splined hub is removed it releases the clamping load on the gasket enough to leak oil onto the brakes and the oring was added as a backstop. Replace the oring and put silicone sealer on the gasket too as it only takes a few drips out of the flange to ruin the shoes.

Andy.

 

[steveg]

I've used pvc pipe fittings of various sizes as seal drivers. Was able to R&R the bearing using this method.

Slight quibble: the seal is not actually in backwards, though it looks it, as the spring side points toward the bearing, where the oil is.

 

[DickN]

Thanks everyone, my leak is on the brake drum side so I will replace only the O ring and gasket.
Dick

 

[British_Recovery]

As far as the thin paper gasket on the axle flange, there are two different ones. The earlier hub, without the o-ring, uses a paper seal with a smaller inside circular opening, while the later seal is cut back so the o-ring is between metal surfaces and not against the paper. They look exactly the same until you line them up.
Bob