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Frustrating Diff problem

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Old Oct 25, 2011 | 11:02 PM
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Default Frustrating Diff problem

Hello, I hope someone can help me figure this out. I had the differential in my '79 rebuilt by a reputable shop. I was rebuilding the rear end in my car, so I removed the unit and brought it in. As part of the rebuild, the driver's side yoke shaft had to be replaced because the c-clip had broken and the end wore down.

After reinstalling the unit, it leaked on the side with the new yoke. I took it back and they put a new seal in it. That didn't fix the problem. So they put a different, thicker seal and roughed up the yoke shaft with fine sandpaper. They used a sealant on the seal seat, checked to make sure there was no play in the yoke that would cause it to break seal suring driving, and checked the vent tube to make sure it was clear. When the yoke shaft was installed, the seal fit snugly around it. In spite of all this, it still leaks.

I'm at a loss as to what could be the cause. Everything seems right, but obviously something isn't. Any ideas, comments, or insights are welcome. Thanks.
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Old Oct 25, 2011 | 11:26 PM
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Originally Posted by MajD
. I had the differential in my '79 rebuilt by a reputable shop. As part of the rebuild, the driver's side yoke shaft had to be replaced because the c-clip had broken and the end wore down.

.

did this reputable shop tell you the clip broke and thats what caused your side yoke to wear? usually the side yoke which is less hard than the center pin wears enough that the clip falls off, the yoke can also wear into the side of the case and that might be your leak problem...
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Old Oct 26, 2011 | 08:52 AM
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Originally Posted by MajD
Hello, I hope someone can help me figure this out. I had the differential in my '79 rebuilt by a reputable shop. I was rebuilding the rear end in my car, so I removed the unit and brought it in. As part of the rebuild, the driver's side yoke shaft had to be replaced because the c-clip had broken and the end wore down.

After reinstalling the unit, it leaked on the side with the new yoke. I took it back and they put a new seal in it. That didn't fix the problem. So they put a different, thicker seal and roughed up the yoke shaft with fine sandpaper. They used a sealant on the seal seat, checked to make sure there was no play in the yoke that would cause it to break seal suring driving, and checked the vent tube to make sure it was clear. When the yoke shaft was installed, the seal fit snugly around it. In spite of all this, it still leaks.

I'm at a loss as to what could be the cause. Everything seems right, but obviously something isn't. Any ideas, comments, or insights are welcome. Thanks.
A seal will generally fail only if the shaft/bearing that it seals has excessive runout. Something is wobbling in there and causing your leak.
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Old Oct 26, 2011 | 11:17 AM
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What redvet said. The yoke wears on the end so as it wears the yoke move more into the housing and if the wear is bad enough the u-bolts on the inner u-joint will start to cut into the housing just like a lathe. If this happens this reduces the area that the seal can sit in on the housing. Did you look at the housing to see if any material had been removed around the seal?

I've see a few 79's do this with the side yokes.

Alo check to see if the vent is open or pressure may cause fluid to get pushed through the seals when hot.
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Old Oct 26, 2011 | 11:41 AM
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Originally Posted by MajD
That didn't fix the problem. So they put a different, thicker seal and roughed up the yoke shaft with fine sandpaper. They used a sealant on the seal seat, checked to make sure there was no play in the yoke that would cause it to break seal suring driving, and checked the vent tube to make sure it was clear. When the yoke shaft was installed, the seal fit snugly around it. In spite of all this, it still leaks.
I wonder why they didn't use a speedy/ready sleeve? Roughing with sandpaper sounds Bubba to me.
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Old Oct 26, 2011 | 12:08 PM
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Originally Posted by MajD
Hello, I hope someone can help me figure this out. I had the differential in my '79 rebuilt by a reputable shop. I was rebuilding the rear end in my car, so I removed the unit and brought it in. As part of the rebuild, the driver's side yoke shaft had to be replaced because the c-clip had broken and the end wore down.

After reinstalling the unit, it leaked on the side with the new yoke. I took it back and they put a new seal in it. That didn't fix the problem. So they put a different, thicker seal and roughed up the yoke shaft with fine sandpaper. They used a sealant on the seal seat, checked to make sure there was no play in the yoke that would cause it to break seal suring driving, and checked the vent tube to make sure it was clear. When the yoke shaft was installed, the seal fit snugly around it. In spite of all this, it still leaks.

I'm at a loss as to what could be the cause. Everything seems right, but obviously something isn't. Any ideas, comments, or insights are welcome. Thanks.


Well take it back to this "reputable shop" if they truely are they will take care of their work! Anything else to be said is truely guess work as we cannot see the item and everything was supposely done already!
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Old Oct 26, 2011 | 07:07 PM
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Thanks for the responses. I suppose I should have mentioned that the diff wasn't leaking before. The old yoke was worn, and the shop did tell me it was because the clip came off. The other yoke was fine. The clip came off before the yoke wore down far enough to cause the u-bolts to touch the housing. Wouldn't you hear something like that anyway? That must make an awful racket. Anyway, the yoke was replaced during the rebuild. It seems that if the bearing was the problem, it would be leaking before I removed the differential, unless it's a coincidence that the leak started right after the rebuild. The vent tube is clear. It seems like the speedy/ready sleeve may be worth a try. Fortunately, the shop is willing to take care of the problem. Thanks.
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Old Oct 26, 2011 | 11:04 PM
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The problem is too much metal has been ground off the side of the case. You need a minimum of .300 depth into the bore for the seal to seal to the case. A thicker seal will only make it worse. I repair these all the time. Did they replace the stub axle bearing with the correct full compliment BH2212 bearing or did they use the replacement style caged roller bearing?
Mike
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