I figure with the extra time I save to do it this way versus the manual I will just change out the fluids in all gear boxes and still save time.

 

thats how i did mine, just mark the nut and flange and tighten back to that mark and you should be good to go. Something that also helps is when you pull the companion flange out you will see a mark or groove where the old seal has been riding, take some scotchbrite or steel wool and make some cross hatching on the seal surface so the new seal will have a good place to ride instead of trying to fall back into the original groove. Any other questions lemme know.

Later

Eli

 

Worse thing that happens if the nut backs off is the pinion destroys itself and the crown gear, resulting in a very costly diff rebuild. I know from recent personal experience when my dealer didn't properly tighten the nut after a simple pinion seal replacement.

 

You can usually detect it way before destruction happens but I suppose there are some cases that would not follow the norm.

 

Well, I have to get mine fixed next week. What are the symptoms of something wrong after repair? What should I be looking for and how long untill I know everything is O.K. ?

 

If they don't get it it will vibrate and/or leak. The easiest way is to put it in 4wd and if the pinion nut backs off you'll know by the harmonic it will cause. You'll feel it in the steering wheel and your butt. If you don't see any leaks or it doesn't vibrate you will be fine. The other way is play in the drive shaft at the pinion. There shouldn't be any play in the pinion at all. The pinion bearings on the pinion shaft are loaded in their tapered races with the tightening of the pinion nut. If play exists then the shaft can walk around and cause the seal to leak and will cause vibration.

 

Mine must have one of those cases that didn't follow the norm. Mine had no signs until I put it in 4WD and terrible crunching noises from the front diff occurred.

There are a lot of occurrences here of leaky front pinion seals. Looking at the pinion seal area, there is an outer cup-shaped metal ring between the pinion shaft and the diff housing that appears to serve as protection for the front seal. The protective "cup" has its bowl facing towards the diff case. For a rear diff, this makes complete sense as the outside of the cup deflects sand/dirt/debris. There is a small gap between the lip of the cup and the diff case--enough space for debris to enter through. So on the front diff, the cup is facing backwards, so now the cup acts like a scoop, catching all the sand/dirt/debris bouncing up off the road and right into the cup where it can get ingested by the seal, causing the seal to leak and eventually fail. This is my hypothesis, anyway. I'm going to look at this and see if there's any way to fab up a small deflector that could be mounted to the diff to deflect debris away from the pinion seal area. I'm thinking of something cone-shaped, kinda like those cones that the vet puts on a dog's head to keep them from chewing their stitches, that could be fastened around the diff case pinion area with a large hose clamp, zip tie, or something.

 

Good hypothesis. I think you are correct. That outer cup should have a way to prevent debris from being trapped under it. Maybe your device could be constructed out of rubber or something durable like that. Keep us posted.

 

But doesn't just about every front diff made use that same design for the dust shield?

My theory on why they leak is that it's due to the full-time front end. I bet the problem wouldn't occur if the front end had selective locking hubs.

 

Yeah I think that's a good possibility too. But here's what makes me think it has more to do with debris and less to do with the full-time pinion rotation:

1) The rear pinion is rotating just as much as the front, but rear pinion seals seem to be holding up better than the fronts. If it were an issue of full-time rotation, I'd think we'd be seeing similar failure rates on rear pinion seals as we're seeing on the fronts.

2) Full-time rotation does help to keep the seals properly lubricated. I'd think we'd see more failures, not less, if we had manual locking hubs (unless owners were disciplined enough to engage their hubs on a regular--at least monthly--basis to keep seals lubricated). And with the pinion spinning all the time, at least there's some chance of debris being deflected away. If it were not spinning, debris may have a better chance of settling on the seal.

 

Good thinking on using rubber. I was thinking flexible plastic sheet, but rubber would be better. It needs to be something pliable and something that, if it ever got tangled up in the driveshaft it would easily shred apart and not damage the driveshaft in any way. I'll start looking for something to fab us as soon as I get a chance.

 

I like your idea, when you get it figured out take some pics and post them.

 

Don't the front and rear diffs use different seals though?

I don't think full-time rotation is really "good" for anything. Even with lockout hubs the front driveline will usually spin slowly at highway speeds which would be easier on the seal and still keep it lubricated.

It still doesn't explain why other 4x4's don't have this problem when they use the same exact dust shield design. If it was caused by debris then they would all leak.

 

Something interesting to note though is I ran my truck in 4wd this weekend. As of today, the leak has stopped. I'm still going to change it but it's not leaking anymore. I know.....I checked the fluid in the diff and it is fine. I was just wondering if the fluid wasn't getting high enough in the pinion housing to "wet" the seal so it dried and shrunk. So, I tried to put it in 4wd and run it good to see. It stopped leaking like I said but I still don't know why.