Rear axle bearing alert

[Petros]

I have just finished changing out my out rear axle bearings at about 212K miles. I had to do this on my '83 at about the same miles and I now realized why: The outer gasket (under the brake backing plate) appears to fail allowing moisture into the bearing causing it to rust.

When the axle bearings fails you get a low roar (increases with speed) coming from the back of the car. It will get worse until complete bearing failure.

They are not too expensive (about $35 each) but they have to be pressed out and the new one pressed back on. Note: If you pay someone to press on the new bearings, make sure they put the retainer ring on the correct way, or the axle seal will not work.

There is not too much load on these bearings so failures should be rare, but after replacing them on both my Terc4wds I think if this gasket seal on the backing plate had stayed good the bearings might not have failed. Between the brake backing plate and the axle housing end there is a metal gasket, it gets corroded probably from brake fluid that leaks down on it when you bleed the rear brakes.

It would be a good idea when you have the rear brake drums off for any reason (like a rear brake job) to remove the rear axle half shafts, remove the backing plate and clean this surface and seal it with silcone sealant (removing any rust from around the bearing area while you are at it). And every time you blead the rear brakes, spary brake parts cleaner over where any brake fluid may have leaked on to this joint (or anywhere else) and flush with water when you are done. The bearing will likely last indefinitely if you keep the bearing area free of moisture.

When this gasket allows moisture to leak into the bearing area it causes rust and will eventually get past the bearing seal. When this area is free of moisture the bearing and axle will slip out without too much trouble once you remove the retainer nuts. When there is moisture in there you have to use a slide hammer (like I did) to get them out. I cleaned out the rust (being careful not to damage the inner seal), but a light coat of grease on the seat and bearing (to prevent corrosion not for lubrication, the bearing itself is sealed), cleaned the mating surfaces good and applied a light coat RTV on both sides of the metal gasket. And then reassemble it.

[mailman]

Petros, thanks, good to know. the mailman

[takza]

Should be moved to the repair section?

[gmeddy]

i just did my rear bearings and put them back in yesterday!
i wish i'd seen this post before!
now i gotta go pull them all out again and do that!
arrgh.
the gaskets that came with my new bearing kits were really really thin and brittle, they would just snap like a dry leaf.
i'm gonna go get some nice new thick gasket paper and cut new ones all the way round.
will take some nice photos just for this thread, aww aren't you special...

[xirdneh]

There is a drain hole on the lower aft end of the plate where the bump is. The water runs out on the backside of the brake plate. It gets crudded up trapping moisture in the bearing area. Not sure if its a good idea to totally seal off the bearing.

[xirdneh]

When this gasket allows moisture to leak into the bearing area it causes rust and will eventually get past the bearing seal.

I'm going to have to disagree with this. The gap between the retainer plate and the axel allows the water to get in. There is nothing you can do about that. The retainer plate has a bump on the bottom aft side that lets the water out. The drain hole is in the brake mounting plate and it aligns with the bump. The drain hole must be cleared of debris otherwise water will collect in the bottom third of the space between the bearing and the retainer plate.

[gmeddy]

so i went home and pulled them both out, cut new gaskets for inner and outer, put sealant on both sides of both, the steel gasket that was on the inside was pretty cruddy, and i put some sealant on both sides of it and put it back in with a new gasket on top of it too, and put it all back together.
the one on the other side the steel gasket was worse corroded and a bit far gone i thought, so i didn't put it back on, i put a new paper gasket with sealant on instead.
i hope this is going to be ok.
the drain holes on both sides were totally crudded up.
i cleaned it all out good.
although maybe now that i've sealed it all up the drain holes wont get used...

[xirdneh]

although maybe now that i've sealed it all up the drain holes wont get used...

If you do not drive through a deep puddle you may never get water trapped between the plate and the bearing.
I live in the north west so i will keep the drain holes open.

[gmeddy]

but if it's seals how would water get stuck in there? how would it get in?
i live in Kununurra, Kimberly, West Australia. We have two seasons here, Dry and WET.
Puddles? hahaha

[xirdneh]

but if it's seals how would water get stuck in there? how would it get in?

I explained how the water gets in about four or five replies back. The retainer plate has a gap between the axle and the plate so gooping up the plate with gasket sealer will not keep water out.