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Brake drum leaking differential oil

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bigjones

bigjones

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Hi folks, me again,

Jacked up the back of the car by the "pumpkin" and then jack stands under the rear spring brackets.

Investigating a rather stiff hand-brake mechanism but got diverted by a suspiciously wet brake drum. Took off the drum and it looks like something is leaking.
OilLeak.jpg


That puddle is oil dripping down from the axle! Feels like oil rather than brake fluid. Brake shoes are soaked.

Looking at the Moss Motors catalog, I'm not sure what to order. The "oil seal", and "hub gasket", right?

Cheers,
Jones
 
And new brake shoes. I did mine last spring, not too hard. When you refill the differential, leave it 1/2" below the fill hole, not until it runs out, or so I was told. BTW both mine were leaking so rear brakes were totally non existent.
 
If you leave the wheels off of some cars the little screws that hold the hub are not enough to keep them from leaking.The studs pulling fromn the back of the hub against the drum wheel and hub hold tight to the thin paper gasket.If your going to leave the wheels off for an extended time its not a bad idea to maybe slip a small piece of pipe over the stud and run the lug nuts up tight on them to hold everyting tight.
 
When I did my rear wheel bearings, I used new paper gaskets and to ensure no leaking put blue RTV on everything. I figured that way I could lube the hind end up to the fill hole and never worry about it again.
 
Excellent thinking, I assume you replaced the O rings at the same time. Should never leak.
 
OK folks,

I have the half shaft out. I do have a new oil seal but I was going to just replace the 0-ring (thanks Jack) and the paper gasket, smeared with RTV Blue (thanks Luke).

What do you rate my chance of stopping the oil leak without renewing the oil seal? (You gotta pull the hub and remove the bearing and who knows what else to actually replace the oil seal)

Cheers,
Adrian
 
Replace the bearing while you are at. Take the bearing number and go to bearing shop and ask for the cross. Cheaper then Moss and will save you braking a axle.

Cheers

Mark
 
Ordinarily I'd agree with Mark (OK I actually never agree with Mark :smile: ) But, since it's saturday, make a copy of the paper gasket - reinstall - torque your wheel back on and see what happens. Worst case scenario you are out time and a piece of paper.
 
Mark, JP and Kim,

I just replaced the gasket and O-ring - let's see how well it has sealed.

As a temp measure, I cleaned the shoes and drum with the Purple Stuff - have not got any laquer thinner hanging around.

If it holds up for a drive around the block, I'll replace the shoes and give the drum a real good cleaning.

Mark, I hear you about replacing the oil seal and bearing - makes sense, but to tell you the truth I have not got the energy. It's now on my list though.

Cheers,
Adrian
 
Adrian

It will work.

Cheers

Mark
 
If you look carefully at the whole assembly, you'll notice a remarkable thing. The pragmatic guys who designed the rear hub arranged things so that if the oil seal leaks, the oil is channeled to the back of the brake backing plate and away from the brake shoes. Very sensible (?!!). So, if you have oil on the inward side of the plate, you've got leakage from the seal; if only inside the drum, probably just that gloriously unreliable gasket/O-ring combination.

I once did a lot of high-vacuum work, so I learned a bit about designing seals. That combination of a paper gasket and O-ring makes absolutely no sense to me--either one, OK, but both? I just can't imagine what they were thinking. In any case, the O-ring alone probably won't make a good seal, because the metal surfaces are too rough, the O-ring they use is too thin, and the amount of compression probably isn't enough either. The paper gasket is legendary for not providing a good seal, probably because it's too thin. So the idea of using some RTV or other sealant makes sense. Even though some people don't use the gasket at all, I think it makes sense to use it, if only to give the RTV something to adhere to and to fill up some of the irregularities. I suspect that, with the RTV, you could leave out the O-ring and never know it.

Only other issue is that if the oil seal is really bad, it could still let oil into the inside of the drum, especially if the hole in the backing plate is plugged. So, if the oil hole is open, and you don't see any oil on the inward surface of the backing plate, the oil seal might be OK. My own experience is that the oil seal is the thing most likely to leak, but of course anything can happen.

Is cleaning the brake shoes with lacquer thinner good enough to restore them? The conventional wisdom is that you should replace brake shoes when they get contaminated by brake fluid or other oil. But if this is generally an accepted method, that's good to know.
 
Sadness reigns.

After I came back from a drive, the thing is still leaking.
Ah well, looks like I'll go ahead and replace bearing/oil seal,shoes.
I'll get back to you all on the progress.

Steve, yeah, the original O ring was totally flat - couldn't even see it at first, makes you wonder what use it is.

Mark, I've heard that the half shaft can snap anytime - usually when just driving around casual. So are you saying that replacing the bearing could help prevent that? (Just trying to get motivated.)

Cheers,
Adrian
 
Make sure the lip of the seal faces outward. Make sure you grease the bearings well before you install them dont skimp on quality of the grease. I use one with a high moly content and have never tossed a bearing. There are double bearing setups available for a reason I dont what to find out why.
 
Yes any play in the bearing and you can snap a half shaft. Double bearings help but only really needed for race app's

Cheers

Mark
 
The o ring is the real problem I should expect.
 
It's really not a big deal to replace that seal. You do need a general-purpose puller to get the hub off, and something to plug the hole in the center of the axle housing so the puller has something to pull against (lousy explanation, I know, but you'll see what I mean). Do a search of the archives and you'll find all sorts of clever ideas for all aspects of this. Left side nut is left handed, if I remember correctly.

Interesting that the o-ring was flat. When an o-ring is flattened like that, it's been over-compressed; i.e., beyond its elastic limit. Might not be the right size. In any case, I wouldn't depend on it. Put one in just so it has the right karma, but depend on the gasket and sealer!

Actually, I do question whether it's necessary to grease the bearings. They're lubricated by rear-axle oil, so as long as there is anywhere near enough oil in the pumpkin, it will get splashed into the axle housings and flow to the bearings in seconds. I always just dip the bearings in gear oil, as the service manual recommends, and that should do it. Also, the grease eventually dissolves in the oil, and I wonder if that's good.
 
Ok folks, thanks for all the tips.

I'm waiting for the parts to come from Moss Motors.

That big nut - do folks go out and buy a socket for it or just use an adjustable wrench?

I've just done the front wheel bearings so I'm in the zone. (Is that the right expression? Hey! I'm hip!)

Cheers
 
Go to Harbour Freight and buy a 3/4 socket set. There are three oversized nuts on 1500 Midgets - the hub, the crankshaft and the nut holding the oil filter adapter. By the time you have bought those three you have paid for a full set, AND you will find many uses for big sockets like drifts for bearings and seals. and that's not all, you can impress your friends with a 3/4 Socket set. (Tim Taylor jumps in here Oo Oo Oo)

https://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=40996

Oh and those nuts - one is left hand thread, the other is right and thread - don't ask us (almost all of us) how we know :smile:
 
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