BJ8 rear axle oil seal

[AUSMHLY]

Hello all,

64 BJ8, rear axle oil seal is leaking again. I replaced it on April, 4th, 2014 with Moss motors part number 535-985. Seems I got 20 months out of it.
Before I buy another one from them, anyone know of of a higher quality oil seal?
Is this a known problem, or why do you think it's leaking again?

 

[Healey Nut]

It's just a standard oil seal .
Take the seal to a local belts and bearing supplier and get an industrial version of the seal ....probably cheaper as well and better quality than the Moss Chinese junk .

 

[steveg]

I do not believe the quality of the seal is the problem.

According to Tom Monaco of Tom's Import Toys, most seal failures are a result of heat from spun rear bearings.

In a previous thread I presented evidence that the Moss rear hub paper seal is too thick and prevents the hub from properly clamping the outer bearing race as is called for in the manual. A paper seal of approximately .004" thickness is required in order for the bearing to be properly clamped. Evidently the o-ring is all that's necessary to keep the oil in the axle and it is possible the gasket is not necessary. I made the gaskets from white 9x12 envelope paper.

You'll be removing the bearing in order to replace the seal. Check the outer surface for polishing and circumferential marks that indicate spinning.

 

[BoyRacer]

Let's get our terms straight. Is it the actual hub seal that is leaking or is it leaking at the axle flange gasket? To replace the hub seal you have to remove the hub and the bearing stays in place. If the oil is leaking into your drum then there is a leak at the axle flange. Read the factory Manual. There is a gasket, an o-ring and a clamping ring and you need to measure all of your tolerances to get it right. And sometimes you have to massage things to make it right. If the bearing has started to spin, it will wear itself into the seat and then your tolerances will be off. You may have to machine the surface of the hub to get back to factory specs.

 

[steveg]

Let's get our terms straight. Is it the actual hub seal that is leaking or is it leaking at the axle flange gasket? To replace the hub seal you have to remove the hub and the bearing stays in place. If the oil is leaking into your drum then there is a leak at the axle flange. Read the factory Manual. There is a gasket, an o-ring and a clamping ring and you need to measure all of your tolerances to get it right. And sometimes you have to massage things to make it right. If the bearing has started to spin, it will wear itself into the seat and then your tolerances will be off. You may have to machine the surface of the hub to get back to factory specs.

Let's not lose track here. We remove the hub with the bearing in place, but we have to remove the bearing from the hub to insert a new seal. If the bearing has spun we have to replace it as well. I was addressing the spun bearing as a cause for the premature seal failure. Tom told me he has replaced 80 of these spun bearings stating that it is the usual cause for seal failure. IMO the thickness of the Moss gasket is a likely cause for the spun bearings as it prohibits properly clamping the outer race of the bearing (as is called for in the manual).

 

[Randy Forbes]

Let's get our terms straight. Is it the actual hub seal that is leaking or is it leaking at the axle flange gasket? To replace the hub seal you have to remove the hub and the bearing stays in place. If the oil is leaking into your drum then there is a leak at the axle flange. Read the factory Manual. There is a gasket, an o-ring and a clamping ring and you need to measure all of your tolerances to get it right. And sometimes you have to massage things to make it right. If the bearing has started to spin, it will wear itself into the seat and then your tolerances will be off. You may have to machine the surface of the hub to get back to factory specs.

Let's not lose track here. We remove the hub with the bearing in place, but we have to remove the bearing from the hub to insert a new seal. If the bearing has spun we have to replace it as well. I was addressing the spun bearing as a cause for the premature seal failure. Tom told me he has replaced 80 of these spun bearings stating that it is the usual cause for seal failure. IMO the thickness of the Moss gasket is a likely cause for the spun bearings as it prohibits properly clamping the outer race of the bearing (as is called for in the manual).

Yeah, I gotta go with Steve on this one; a couple days ago, I was rooting through my spares to see if I already had what I needed on hand to swap in a (stock/used) 3.91:1 differential (my existing 4.10:1 may finally get those Lempert 3.54:1 gears I bought about a decade ago...).

I do have the parts I need, so it was easy to grab a caliper and measure a couple of Moss hub gaskets. They do in fact measure between .0115" and .0125" (depending on where the readings are taken). While I never measured an original, I do remember them being quite thin and brittle__clearly not enough material there that they could shred, or separate in layers.

I last replaced my hub seals around the same time as ausmhly did, because of leaking, so I wanted to be sure I had ALL relevant parts on hand before breaking into this. Thanks to what Steve and Richard report above, I will be taking a closer look__and measuring__the stack-up before reassembly!

 

[BoyRacer]

Yup, I got that one wrong. I was thinking the seal was pressed in from the back side. Steve's correct, the bearing has to come out first before a new seal goes in.
The whole key to this business is having that steel ring clamp down onto the outer race of the bearing to keep it from turning. It only stands proud of the hub a few thousands of an inch. If you use a gasket that's too thick, the ring can't do it's intended purpose. I think a good solution is to use a very light coating of silicone instead of a paper gasket. As you tighten things up with the silicone not yet set, you can squeeze out any excess to allow the clamping ring to do it's thing.