48 coupe- Question about how oil gets on the rear brakes

[Bolts]

Recently when I had the rear hubs off, everything inside the drum on the driver side was an oily mess.
This problem has been discussed but the question I have wasn't really explained in detail.

So---
Here's the question. How does oil get into the brakes?

If I am understanding how the rear grease seal works, I think it should keep rear end oil out if it's working properly. Is that a good assumption?

I worry because I don't want my new brakes to get ruined and am wondering if a bad seal inside the bell housing could let the oil get into the drum.

Thanks.

[cmbrucew]

Worn bearings and races will allow the seal to leak.
Bruce

[Ken/Alabama]

Worn out seals inside the axle housings.

[Bolts]

Originally Posted by Ken/Alabama

Worn out seals inside the axle housings.

Thanks for the reply Ken. But, even though oil passes through the internal seal, doesn't it have to get past the wheel bearing grease seal in order to get into the brakes?

I understand Bruce's point about the worn bearing race not sealing, but if the race is good and the seal is new, can oil still get in?

[PeteVS]

Try to keep in mind that all the seals from the ends of the axles to the front end of the drive shaft have to be oriented to keep pressure and oil going to the front of the driveshaft. If any of the seals are installed backwards, they allow oil to flow out at the ends of the axles or trap it which will probably force it out at the axles. If you look at a modern seal, you will see a lip. if the pressure comes on the side where the lip is pointing, it will hold the lip down and prevent leakage. If the pressure comes from the other side, it will get under the seal and lift it up allowing leakage. The seal is basically like a check valve. Install it backwards and you might as well leave it out.

[Ken/Alabama]

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Originally Posted by Bolts

Thanks for the reply Ken. But, even though oil passes through the internal seal, doesn't it have to get past the wheel bearing grease seal in order to get into the brakes?

I understand Bruce's point about the worn bearing race not sealing, but if the race is good and the seal is new, can oil still get in?

I suggested the seals inside the axle housing because where else is oil gonna come from other than the differential.

[Bolts]

Thanks to all.
Still hoping to ease my concerns about this, so let me ask it this way: Would those who have had oily rear brakes chime in and explain their findings and what they did to fix the problem?

[Kube]

Originally Posted by Bolts

Thanks to all.
Still hoping to ease my concerns about this, so let me ask it this way: Would those who have had oily rear brakes chime in and explain their findings and what they did to fix the problem?

I'm siding with Ken big time on this one. I have a lot of experience with this issue and it has always been poor axle seals.
The seals near the bearings will hold back the grease "okay" but mix in oil, and then too much and it will get past the seal and on to your brakes.

[JM 35 Sedan]

Originally Posted by Ken/Alabama

I suggested the seals inside the axle housing because where else is oil gonna come from other than the differential.

If someone uses the wrong lube in packing the rear wheel bearing, or if too much chassis grease is pumped in through zerk fitting on drum end of axle housings, you could have oil bleeding out of that grease and getting on parts inside the drum.

[JSeery]

Might want to look at the post on Venting your axle housing. If something is causing pressure to build up in the housing and the original setup is not buffering this pressure you might need a vent to relive the pressure.

[Bruce Lancaster]

My experience has always taken this straight to the axle seal. You should know for sure just by smelling the oil...
The job is lengthy because you have to pull the housing apart, but not particularly hard.
Measure the housing gasket...probably the normal 010...and replace it with same thickness to maintain gear settings.
Be careful as things go together because axle shaft end is unsupported and floppy until you attach its hub, and you don't want it to damage your new seal.
Tool...I have the KRW driver for the seal, but there is a cheap substitute to make life easy and once you see how it works you could assemble a usable right at home depot.
Brattons sells the pre-made one, which screws onto a piece of water pipe:

With seal supported by this type of holder it pops right into its socket.

[Ken/Alabama]

Originally Posted by Bruce Lancaster

My experience has always taken this straight to the axle seal. You should know for sure just by smelling the oil...
The job is lengthy because you have to pull the housing apart, but not particularly hard.
Measure the housing gasket...probably the normal 010...and replace it with same thickness to maintain gear settings.
Be careful as things go together because axle shaft end is unsupported and floppy until you attach its hub, and you don't want it to damage your new seal.
Tool...I have the KRW driver for the seal, but there is a cheap substitute to make life easy and once you see how it works you could assemble a usable right at home depot.
Brattons sells the pre-made one, which screws onto a piece of water pipe:

With seal supported by this type of holder it pops right into its socket.

I also tape the keyway around the axle so the sharp edge of the keyway doesn't cut the new seal.

[bobH]

The 'guys', in particular Ken, Kube, & Bruce, have it nailed for you. What I didn't see mentioned... don't over-fill the rear-end. I've even seen old posts where it is suggested to leave the fill-level a little low, like maybe 1/4 or 1/2 in below the fill plug. And, don't purposely aggrivate the situation by parking on a side-hill.
JMO

[Bolts]

OK, thanks for the information. I was a little concerned that the gear oil might mix with the wheel bearing grease and get past the seal. I was wondering if that was why the Ford engineers put the little sheet metal cups on the backing plates, thinking possibly any oily goo that leaked out would get trapped in the little reservoir.
Any one know why they're there?

[cmbrucew]

Bolts
I always believed that was why henry done it.
Bruce