Rear Pinion Seal

[Speedy Eagles]

 My rear pinion seal is leaking on my 1985 Eagle Wagon. I have never replaced one before. Looking for tips on how to replace/make sure I get it assembled with the right torque specs.
Thanks

[BenM]

Here's how I did it. Step one is the most important!

Mark on the nut, pinion yoke, and pinion to line them back up.
Take it off with an impact wrench, that's the only way.
Pull the yoke off, you may have to tap it a bit.
Carefully remove the seal without scratching anything.
Insert the new seal, try to alter the depth slightly so it doesn't wear in the same spot.
Line up and replace the pinion.
Tighten the nut by wrench as best you can.
Check the alignment marks. You want to carefully use the impact wrench to turn the nut about 1/8" more. You can go to the mark and see if it takes 15-25 inch-pounds of torque to turn the pinion, then tighten until you get there.

The important thing with the rear is that it uses a crush spacer, and if you completely collapse it you have to pull it all apart. The small additional amount is an approximation to bring back the pinion pre-load into spec without completely crushing the spacer.

I'm not saying this is the best way, but it's the shade-tree way.

[mach1mustang351]

As a former professional tech my view was always unless it is leaking heavily to leave them alone until overhaul is necessary I have never felt comfortable messing with the pinion like that. But if it is leaking badly the post above is very good. That is the best possible without a full ring and pinion setup.

[Canoe]

Here's how I did it. Step one is the most important!

Mark on the nut, pinion yoke, and pinion to line them back up.
[...]
Check the alignment marks. You want to carefully use the impact wrench to turn the nut about 1/8" more. You can go to the mark and see if it takes 15-25 inch-pounds of torque to turn the pinion, then tighten until you get there. ...

After checking various jeep forums, what I did is very near to the above, except:

• after removing the drive-shaft/universal from the yoke, in addition to making the alignment marks (nail polish), I counted the threads exposed above the nut AND took a photograph showing those threads where the alignment marks were
  
• lubed both the new seal and the yoke surface with Red Line CV-2 (lube was recommended by many, be it with the diff oil or a grease, and CV-2 came up a few times and I had that)
• tiny application of black RTV around the contact surface of the new seal's metal ring (recommended to ensure no leaks there; didn't see any report of a leak there, but I figured why not...)
• small application of blue/semi-perm thread locker on splines of both shaft & yoke (recommended to ensure the oil can't leak out along the splines)
• small application of blue/semi-perm thread locker on old nut (was recommended if you re-used the old pinion nut. No one in town had one!!! Didn't know what to order!!!).
• nut on and re-torqued ONLY by prior alignment, plus the extra 1/8" rotation (no torque wrench/measurement), went there with standard ratchet and a bit of elbow grease

Drove perfectly, no noise accelerating nor when off the gas.

Tried getting the nut off with socket & breaker bar. Then with an extension pipe. ha ha No way. Cordless small weekend-warrior impact driver; again, no way. All marks still aligned exactly, photo of threads confirms same thread exposure: none of those methods made even the slightest budge. Everyone says these don't work, but of course I had to try...

So, corded electric impact and in eight seconds it was completely off.
Ten to fifteen minutes to get the old seal off without damaging anything.
The rest was super easy. Didn't have to tap nor use gear puller to get the yoke off - slid nicely out.

One pause/glitch. At the start when I pulled the drive-shaft universal off the yoke, the vehicle moved a tiny bit as the vehicle moved to rest against the wheel chocks instead of the trans in Park. In that, the drive-shaft & yoke both counter-rotated, enough to put the drive-shaft to yoke to diff alignment off. So I re-marked the diff to match the yoke and continued. Upon reassembly, the drive-shaft was off the yoke-to-diff mark by around 30 degrees. Put the gear selection in neutral and the drive-shaft was fully turnable; aligned marks to yoke and bolted back up.

With all of the dire warnings about doing this, and this way and the difficulty, I was rather pleased how easy this went.

[TheBirdman]

I never bother counting the threads, I just torque down the nut enough but not too much that it crushes the sleeve. I actually did one a few months ago, I used cad and a 3d printer to make a perfectly sized seal driver that fit over the pinion shaft to align it. Prior to that, I always used to order two seals as there was about a 30% chance Id get impatient and mess up the first one.

[Canoe]

> I just torque down the nut enough but not too much that it crushes the sleeve
Problem is, how to know that you're there...

It was easy to feel when the nut was in enough that the pinion was now starting to get torqued. I could feel another change when it was just a touch before the marks were aligned. But I would not trust feel to know when I was "there".

Between the alignment marks you make on the shaft & pinion nut, and the thread count (photo memory/backup/confirmation), you know you're back at the identical position, hence idential torque, it was at before you took the nut off. (Of course this is on the assumption that it was at the correct torque before you took the nut off - with no noise when accelerating nor when letting off on the gas.) If you go the extra 1/8" rotation, that's supposed to compensate for wear; most (but not all) people report that works for them (YRMV).

The printed seal driver sounds great! What material?
I did the usual set & tap with a body hammer, then realign and try again. Repeated several times before the seal's ring actually set in a touch. Then it needed a number of gentle taps to get it fully square. Then the usual gentle no-rush tap, tap, tap around the ring until it's in flush. With no rust in play, and determined to be gentle, I was brave and didn't even have a piece of wood between the hammer and the seal. A seal driver is the smart way to do it, even if just a piece of wood with a hole drilled out for the shaft. One of those 'don't do what I do, do what I say' things.