Could a Tech give me an idea of what is involved in replacing the front seal (at the driveshaft) of my rear diff. I has sprung a big time leak. A quick walkthrough would be greatly appreciated. I'm making several assumptions here, that there is a replaceable seal, that it can be replaced without removing the diff, and that no special tools are absolutely required.


Thanks in advance.

You could do it yourself, but I would take it to a reputable dealer to have it done. Here's why: those seals can sometimes be a pain in the a$$ to get out if you dont have a seal puller and a puller for the pinion flange. After you get the new seal installed, you need to set the pinion bearing preload. If you get it wrong and wipe out your pinion bearings, you own it! Dealer would probably charge 1.0-1.5 hrs labor, $75-$125, and then if they screw it up, they own it. But if you're determined to do it yourself, be prepared with a puller to get the flange off, sometimes they can be tough, other times they jump off by themselves. A seal puller would be nice so that you don't damage the housing removing your old seal, seal installation is pretty straightforward, use some teflon paste on the splines of the flange when re-installing. Hint- to set the pinion preload up the same as when you took it apart, mark the nut/pinion with a chisel and then line them up when you go back together, and maybe just a pinch more. Don't let that pinion move around too much if you're using an impact gun to loosen/install nut.

OH yeah, check your flange and make sure you don't have a groove in it where the seal rides, at least not a deep groove.

I've seen mechanics take a mallet to the back of the yoke to get it
off. Not good practice but you see it being done. Usually it slides off
the spline after a few taps if it isn't loose already.



If you do decide to do it, make sure you mark the big nut. Basically if
you tighten the nut back to the same marks, there's no torquing or
measuring required.



Drop the drive shaft

Mark the nut by drawing a line with white paint accross the nut and into the center of the pinion ....and remove the nut.

Remove the yoke

Pry out the old seal carefully

Tap in the new one carefully

Reinstall the yoke

Reinstall the nut to the same position

Reinstall the driveshaft.


Edited by: hoot

VFR, I posted a reply in the other forum where you posted this. It's easy to do. http://dieselplace.com/forum/forum_posts.asp?TID=1007&KW (http://dieselplace.com/forum/forum_posts.asp?TID=1007&KW=pinion+seal) =pinion+seal

Thanks for the input, I'll tackle it next week.

I've changed out the Pinion Seal, was a PITA, I had to make a puller out of 2 different pullers and fab a bracket to bolt it to http://www.dieselplace.com/forum/smileys/smiley7.gif. I did as said, marked the nut and pinion, but now I've run into a problem. When I reinstalled the pinion nut, I'm not sure if I've got it turned down far enough. I failed to count the threads before I took it off, http://www.dieselplace.com/forum/smileys/smiley9.gifand now I think I'm one full turn light. But I'm not sure, since It's a bugger and is fairly tight, and I don't want to try and send it around one more turn and waste the bearing if I'm wrong. But I do think I remember less of a gap behind the yoke, but I'm not sure. What is the preload for the pinion, can I do it myself with a regular torque wrench? I'm assuming if I'm light on the preload, my bearings won't last long. Can anyone see how many threads are showing on the pinion sticking out past the nut on thier truck, might let me know if I'm a turn off. I've got 2 showing.


Could use a hand on this Socal.

Normally you check preload when the ring is not installed so you can
freely rotate the pinion. It's done with a inch pound torque wrench.
You sneak up on it until you have so many in/lbs of load.



But since you aren't removing the ring gear, you should be able to
tell if it's not too tight just with the normal backlash. You should be
able to feel the backlash easily. Driveshaft removed, grab the yoke and
try and turn it back and forth. If it feels locked tight, you are too
tight, There should be a little play in it.



Next, push in and out on the pinion. You should have NO play in the axial direction at all.



One full turn of the nut, either not enough or too much should be obvious.



If you went too tight you got a problem. You'll have to tear it down,
remove the pinion and replace the crush spacer and possibly pinion
bearings.


Edited by: hoot

hoot is right, try moving it in and out you, you should feel no play. If think if you went a full turn too tight it will be hard to turn. You can't properly measure the preload with the whole thing assembled. Does it feel loose?

Got it done, it was one full turn loose. It was very decieving, It was so snug there was no play until I let it turn under power which loosened it up, I immediately noticed a wobble on the yoke and dissasembled and turned the nut one full turn. It would not go the last 1/4 turn even with a handle extention on the 1/2" drive, I carefully used an impact to send it back to the mark. Works fine, no leaky. All said if a dealer can do it for $150 or so I'd recommend that unless you've done it before and have all the needed tools (puller, impact). Like has been said, there is a lot at stake if you ruin the bearings, I cant imagine what a rear end shop would want for a rebuild.