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From: Syracuse-Central Square New York Winer of the all Corvette race WGI 8/23!
Originally Posted by leigh1322
That's really bad.
That means you pinion gear is moving forward and backward on your ring gear. Not good.
I would not even bother changing that seal now, you may be going much much deeper.
The first thing I would do is to check the diff oil for level, and for any glitter present.
Then may as well check the side yokes for movement.
Personally, I would yank that diff and open it to inspect it, and then go from there.
I was a bit shocked as this car only has 37k miles and its super clean. That shaft should not wiggle around with a bearing just inside of the yoke, correct, or can it be loose until the yoke gets reattached?
The yoke is what loads the two bearing(s) together.
Without the yoke, yes, it willcan be very loose.
Hopefully you scribed a mark on the pinion & yoke so you know exactly how tight to get the pinion nut, to replicate the original setting..
It is a crush collar, and you can not go by TQ alone.
Last edited by leigh1322; Apr 28, 2025 at 11:51 AM.
No there is a Bearing in the front that the shaft passes through. There is no bearing clearance it is a press fit and therefore no wiggle room. I would assume the Bearing has failed and that makes sense that it started as the Yoke is no longer centered in the Seal. I might consider doing the Drain Plug modification that can be found here on the forum. When the Oil Drains out, I would expect the Bearing debris to come out in the Oil.
If your in need of a replacement Rear End PM me but I'm a long way away..
The bottom bearing on the pinion gear is indeed a strong press fit, and the shim underneath it determines the gear pattern.
But the outer pinion bearing, by the yoke, is anywhere from a light press fit to a slip fit.
If it is a slip fit, with the yoke & nut off, it could make the pinion very loose. Normally they take a light hammer to tap partly on, then the nut presses them on the rest.
Both pinion bearings are tapered, and have separate races, so the tightened depth of the pinion nut, and the solid/crush spacer, determines their tightness or looseness. This is tested via the rotational TQ test with a dial inch-lb meter. But on the bench, both the pinion and the carrier have separate rotational values. Tough to do in the car.
You could TQ the pinion nut to a little tight, and recheck it for vertical looseness then. But what TQ?
The real trick to replacing this nut & seal in the car, is to have measured / marked the nut before it came apart.
If someone did not do this seal replacement properly, last time, or ~20 yrs ago, you could have all kinds of issues now.
Too tight kills the pinion bearings, and so does too loose.
If it was loose before dissasembly, I would pull the diff.
If you did not mark or test the pinion & nut before dissasembly I would pull & rebuild the whole diff.
If tightening the nut "some" does not eliminate that looseness, I would pull the diff.
IIWY I would proceed very cautiously.
Hopefully Gary will chime in here. He knows more about these diffs than 20 of the rest of us, put together.
Last edited by leigh1322; Apr 28, 2025 at 12:01 PM.
That is a DANA 80-82 type, as you know. There is no crush sleeve in those, they use shims. The seal is different than the iron diff's. Personally, I hate those diff's. Yes, I know many rebuild them and have good results. I'm good with that.
I would follow the manual procedure. If you just pulled the yoke, you should be able to replace the seal and get it back. Those diff's have the bracket cast into the housing, that doesn't help doing it on the car. Check the axle endplay as well as they had issues, the cross shafts were soft, the clutch retainers get chewed up and the cap fit isn't always good.
I got rid of all the parts I had for them years ago. If I had an 80-82 and planned on keeping it, I would convert to an iron diff and be done with it.
From: Syracuse-Central Square New York Winer of the all Corvette race WGI 8/23!
GTR, Yes I learned these 80's do not have a crush sleeve. Makes a world of difference when just replace the seal that was leaking. We put some permetex on the seal and shaft torqued the nut as the specs said to 210 ish and got it done. The car only has 35k miles on it so were hoping the internals are ok, the outer shafts seem tight too. Thanks everyone for the help.
This car has a new fill plug that is huge! I cannot find the drain plug it's been a few years since i played with these, any thoughts?
Rear diff pinion issue?
