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MG MGA - Inner workings of the rear hub

There's oil driping out of one of the rear brake drums.
So clearly there a failure in the oil seals somewhere and gear oil is dribbling out.

I've seen the fix described on Barney's web page in some detail, but have a question about how these things work.

There appears to be an oil seal between the wheel bearing and the inner hub. Then there is a paper gasket and an O ring between the splined hub and the inner hub (its a wire wheel car).

My question is about the internal oil seal between the wheel bearing and the inner hub. Is this seal intended to prevent ANY gear oil from migrating from the rear end body? It appears that the wheel bearings are supposed to get oil froms somewhere!

Or is that seal intended to control the flow of oil from the body to the hub? In which case its failure is allow too much oil in?

I guess I'm confused by why Barney indicates a fix to an oily drum is immediately to go for replacement of that seal rather than the paper gasket and O-ring?

Additionally on a scale of 1 - 5 (with 1 being easy)how hard a project is this? My biggest concern is the bearings (I don't have an arbor press)also I'm thinking that for $40 for the socket to remove the hub nut I'm already almost into an hour of a mechanics time, so it this is something he can whip out in 2 hours it might be worth having him do it?
Tysen

Tysen, leakage at either the paper gasket / O ring or the shaft oil seal will oil up the drum. The paper gasket seal to the flanged end of the shaft should not leak once assembled correctly because there is no wear. This flange has an O ring as well on most but not all hubs. The most likely leakage source is a worn shaft seal. The hub shares the same oil space as the differential. To replace the seal you have to pull the hub off the axle. Take out the axle first. Tilt the car up on the jack so the oil stays in the diff. The seal is in the back of the hub behind the bearing. If the seal area on the axle is corroded or badly worn it will need repairing with a 1-15/16" Speedi Sleeve from Chicago Rawhide. See Barney Gaylords site for detail how to install - its easy to do.
Art

Art is right jack the car up from the side to keep the oil in the diff.
The only part of this job that needs a special tool is removing the 8 sided nut and then retorqueing it. This is where an old fashioned bending bar torque wrench is good to have, it doesn't care if right or left hand thread. Buy the socket tool.
The bearing stays in the hub for this operation and need not be touched. Besides the bearing is removed with a hammer and punch not a press.
Always replace all 3 sealing pieces 1 seal 2 gasket 3 o ring. The bearing rides in axle oil and needs no other lubrication.
If you do it your self not only do you learn but for less than the cost of paying someone like me you get to buy a neat new tool. "Honey, I have to buy the socket it saves $$$"
Randy
P S replace the shoe if oil soaked. You Can't clean it. Even if it looks clean there is oil inside the shoe material that will "boil" out of the shoe when it gets hot and glaze the surface and make the shoe slippery and inefective.
R J Brown

Before going the SpeediSleeve route, try polishing the surfaces with polishing cloth, and use a slightly tighter seal, it will work well.
dominic clancy

Thanks all.

RJ, I'm a little confused by something you said about the bearing not having to come out.

On Barney's page and on all the parts plans I've seen it appears that the seal is between the bearing and the inner hub so the bearing would have to come out?

did I miss something?
Tysen

It has been too long and my memory is failing. The seal is below the bearing so the bearing does have to come out first. I just called NAPA and Car Quest with the part # Barney gives for the speedy sleeve both have it in stock for about $30. A press would make it easier but a large socket and a heavy hammer works. I try to be carefull about what I write, sorry.
R J Brown

Not at all RJ I really appreciate you taking the time to answer.

Cheers!
Tysen

Tysen, when extracting the rear bearing from the hub, you have to press against the inner race and the balls transmit the force to the outer race in the hub. DON'T HAMMER! unless you really want to fork out for a new bearing. Just press steadily with vice, G- clamp, press whatever works
Art

I just finished up this R&R on my 1600 MKII.
Here's my recipe:

Tools:
#3 Phillips screwdriver
Cold chisel
Wood chisel (You won't use it on wood again)
1 61/64" octagonal socket (Moss 384-905)
Long handle socket bar
Brass drift punch

Parts:
Oil Seal (Moss 120-900)
O-ring (Moss 121-400)
Paper gasket (Moss 296-100)
Octagonal nut lock tab (Moss 267-450)
Hub lock tabs (2 x 267-450)

Replace octagonanl nut (267-440 or 430) if someone took a cold chisel or pipe wrench to it earlier.

Remove the wheel, then use wood chisel to separate the lock tabs on the 4 hub nuts enough to where you can use the cold chisel flatten them out. Remove the 4 nuts and lock tabs.

Be sure you have the brakes backed off - especially the parking brake. Also back off the adjuster on the rear slave cylinder through hole in the hub. The hub should pull right off. Be carefull not to nick the threads on the 4 hub nuts.

Use the #3 Phillips to remove the set screw that holds the hub to the bearing housing. The axel should now pull right out, unless someone used gasket sealer on the old paper gasket. Try the wood chisel again to loosen if needed.

Use the wood chisel once again to separate the lock tab on the octagonal nut, followed but the cold chisel to flatten. Be careful here, you're right next to the bearing now.

You really need the octagonal socket at this point. It isn't the best quality tool, being pressed rather than forged, but it worked for me. Take care to keep it centered on the nut, and back off if it starts to slip. If you're on the left hand side, remember that that that side has left hand threads.

Use your rawhide hammer to loosen the bearing assembly, and it should pop right off. Lay it down on your workbench on a couple of 2x4's, supported by the 4 hub bolts. Use the brass drift and a small hammer to tap on the outer race and slowly work it out of the hub. Remove the old seal the same way.

See mgaguru.com if you can feel ridges on the axel where the oil seal turns, you'll need the "speedi-sleeve". If not, replace the oil seal and return the bearing and hub assembly onto the axel. Be sure and use a new lock tab, not the old one, torque down the octagonal nut (140 ft-lbs !?) and use the chisels to set the lock tab.

Last trick is to be sure and put the o-ring on the half-axel, not in the groove on the hub/bearing unit. It is easy for it to get out of place and get pinched or nicked when you slide the axel back in. Don't forget the paper gasket.

That about does it! Worked for me, but I'm sure that there are plenty of other things that could go wrong.

Only took me a couple of hours to get this done. Second one done in 30 minutes, once I had the tricks figured out.

Best regards,
Chuck Mosher
Chuck Mosher

Tyson,
Were all the screws tight? Unlike steel wheels, there are no lugnuts to compress the paper & o-ring seals. I just rebuilt mine and had problems until I remembered to tighten the screws.
BOL,
Doug
D Sjostrom

Wow Chuck!

Nice description!!

The only thing I'm a little unclear on is the lock washer on the Octagonal Hub nut, it doesn't appear that the PO did anything to bend it back as you described it just appears that the nut is tighted down on it.

Can you describe that a little more.

Thanks mucho!

Doug thanks for that I will double check!
Tysen

Tysen,

The lock washer for the octagonal nut has an inner tab that fits into a hole in the threaded axle. This "locks" the washer to the axle housing. After you tighten down the octagonal nut, flatten the washer against the nut on one or more sides to lock the nut to the washer, and thus to the axel. I used the wood chisel to get it started, and then used the cold chisel to get it flat against the nut.

On my first MGA, I had an unfortunate - but comical experience with that blasted octagonal nut. I was making a right turn, when I heard a bump and the right side of the car dropped a bit. I looked over my shoulder, and the right axle was drifting out, extending the wheel, looked like a cartoon. I managed to stop before the axle came out completely. The lock washer had not been used, the octagonal nut came loose.

The threaded axle housing was bent out of round by this experience, and I couldn't afford a new one. So I took a file to the out of round part, filed it down, then re-created threads with a jewelers file. Actually worked, believe it or not.

You don't want this experience, so be sure and use that lock tab !

-Chuck
Chuck Mosher

This thread was discussed between 25/09/2005 and 02/10/2005

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