Diff pinion seal leaking
Thread Starter
Drifting
Joined: Jul 2020
Posts: 1,501
Likes: 323
From: San Diego
Diff pinion seal leaking
So I screwed it all up and Im not sure how to fix it. When I got my new diff, I pulled the front yoke out to ensure I got the correct u-joint and clamps. Anyway, when I did, I did not realize that the pinion nut has a specific adjustment for it and I did not take any measurements before. I put it all back together and made sure it was spinning without and restriction but it started to leak immediately.
I pulled it off again and replaced the seal thinking this may be the issue. Since I didnt have the measurement I just adjusted it snug. I noticed I had a clicking in the rear end and the seal failed within a few miles.
Is there a way to properly figure out how tight the bolt should be or do I need to take it to a shop at this point? OR, could there be another reason that it could start leaking immediately?
I pulled it off again and replaced the seal thinking this may be the issue. Since I didnt have the measurement I just adjusted it snug. I noticed I had a clicking in the rear end and the seal failed within a few miles.
Is there a way to properly figure out how tight the bolt should be or do I need to take it to a shop at this point? OR, could there be another reason that it could start leaking immediately?
Melting Slicks
Joined: Nov 2006
Posts: 3,426
Likes: 1,830
From: Apple Valley, MN
Unfortunately, you have committed a cardinal sin. There is a crush sleeve between the two pinion bearings that is integral to managing the bearing preload. Since you did not mark the position of the nut, you have no way of restoring the bearing preload to its setting before you took it apart. Tightening the nut (and crushing the sleeve) during assembly takes a LOT of torque. You can’t just “snug” it.
Installing the pinion seal properly is not difficult but it requires some knowledge. One big mistake many people make is pounding the seal in so the flange mates with the housing. NO! You must maintain a gap of 1/8” between the flange and the housing. Another mistake is failure to seal the splines with a proper sealant.
There are a lot of posts on this forum on how to properly set the pinion preload. Educate yourself on how to do the job properly, then decide if you can tackle it or take it to someone who knows how to do it right.
Installing the pinion seal properly is not difficult but it requires some knowledge. One big mistake many people make is pounding the seal in so the flange mates with the housing. NO! You must maintain a gap of 1/8” between the flange and the housing. Another mistake is failure to seal the splines with a proper sealant.
There are a lot of posts on this forum on how to properly set the pinion preload. Educate yourself on how to do the job properly, then decide if you can tackle it or take it to someone who knows how to do it right.
Tech Contributor
Joined: Aug 1999
Posts: 15,214
Likes: 4,037
From: Connecticut, USA
Yes and no on the seal install. Years ago, the GM manuals specified the gap between the seal and housing and that was correct because of the bore depth. However, hands on experience with these diff tells the true story and that is GM had lousy QC during the 70's. I measure the bore depth, seal thickness, and figure the clearance between the yoke and seal flange on every diff I build. I have found the bore depths vary and some are shallow enough to cause interference between the yoke and seal.
There is no torque rating for the lock nut since you are measuring drag on the bearings not load on the nut. If the pinion seal is leaking you need to remove the diff. Mount it on a stand and get a good dial TW, 0-30 in/lb and check where the drag is. With used bearings it should be 5-7 in/lb.
I wrote this 15 years ago, I can't believe how time flew by, but it will explain it better for you.
63-79 Pinion Seal Replacement | Corvette Forum : DigitalCorvettes.com Corvette Forums
There is no torque rating for the lock nut since you are measuring drag on the bearings not load on the nut. If the pinion seal is leaking you need to remove the diff. Mount it on a stand and get a good dial TW, 0-30 in/lb and check where the drag is. With used bearings it should be 5-7 in/lb.
I wrote this 15 years ago, I can't believe how time flew by, but it will explain it better for you.
63-79 Pinion Seal Replacement | Corvette Forum : DigitalCorvettes.com Corvette Forums
