DaveH71

So my pinion seal on my stock 10 bolt is leaking. I already have a new seal. Just wondering if there are any tips for putting the new seal on or getting the old one off. Also what to retorque the nut to so i dont mess up the crush sleeve. Any tips would help alot. Thanks alot. 94 z28 by the way.

NonGoggleGuy

Just did mine recently.

1. Remove the torque arm (not necessary, but will make it easier).
2. Remove the 2 strap bolts on driveshaft flange & pull driveshaft towards rear of car to remove.
3. Remove pinion nut & then use a 2- or 3-jaw puller to remove the flange.
4. Use a small screwdriver to carefully pry off the old seal. Don't worry about mangling the seal, but be careful of the pinion itself. All oil will leak out when doing this.
5. Once the old seal is out, allow it to drain fully. Then clean off any remnants of the old seal.
6. Position the new seal into the pinion. I'm sure GM sells a special tool to make this easier to press in, but I used a 2-inch (I think) PVC piping to position inside the lips of the new seal. I used a rubber mallet with a block of wood on the end of the PVC pipe to slowly and annoyingly pound in the seal.
7. Re-install the driveshaft & torque arm (if removed). Take off the 3/8-inch fill bolt on right side (I believe) of pinion, and fill with oil - I used 75W-90. And don't forget 4oz of posi additive.

1 FMF

iTrader: (1)

dude you left out the most important part, properly torquing the pinion nut back on.
how did you tighten down the pinion nut?

angel71rs

You are supposed to mark the nut/flange so you tighten back to the same spot... or so I've read.

But I recently had to deal with a leak on mine that wasn't the seal. Damn nut was loose, lube was coming up the splines, out past the nut.

Since I had no mark as reference, I researched on the net and found many posts suggesting torquing to 120-150 lb/ft in this situation. Consensus of opinions I read was that this was enough to keep things in place, but not enough to compress the crush sleeve any more, causing an increase in pinion bearing preload.

Seemed ok to me cause I've done gear swaps before and can tell you it takes much more than 150 lb/ft to crush the sleeve.

So I popped the rear cover off to drain the oil, didn't want lube to come up while I had things apart/cleaned. Dropped rear of drive shaft, did not remove from tranny, didn't want to lose atf (did not remove TA), removed nut, flange slid off on it's own. Cleaned area up, sealed outer end of splines as I reinstalled flange, installed nut with red locktite, torqued to 120 ft/lb. Then I marked nut/flange for reference to see if nut loosens.

Popped on a new gasket, filled. Been a few weeks, no issues since, nice not to have drips on my garage floor anymore. I'll be checking the mark anytime I'm under the car for oil changes, etc.

NonGoggleGuy

Yeah, sorry.. I did forget that.

Before removing the driveshaft, mark the driveshaft position to flange with white-out.
.
If you have an in-lb torque wrench, measure the drag resistance on the pinion nut - should be low, most likely under 10. *I did not do this. Instead, I marked the relationship of the pinion nut-to-pinion-shaft with white-out. This works just as well.*

1 FMF

iTrader: (1)

sorry, i meant to say preload on the pinion bearing, not necessarily torque on the nut.
i remember hearing a lot of stories in the past where guys had their pinion seal replaced only to have the pinion bearing toast 1000-5000 miles later because the mechanic overtightened the nut and overloaded the pinion bearing (as in too much preload).

i have the 2002 service manual and those numbers are

rotating torque values for just the drive pinion bearing preload
with new bearings & new oil seal = 15-30 lbin
with used bearings & new oil seal = 10-15 lbin

the total preload with carrier installed
with new bearings & new oil seal = 32-55 lbin
with used bearing & new oil seal = 16-28 lbin (your situation)

I recommend you research pinion depth, pinion to ring gear wear pattern or tooth contact, and backlash if you are not familiar with them. The smart thing to do is after getting pinion preload correct, recheck the contact pattern of the pinion gear to the ring gear with gear marking compound and also measure backlash. This will ensure the rear end is set up properly and you don't toast the pinion bearing or prematurely wear out the pinion/ring gear, chip teeth, etc.

after the new seal is installed, you tighten down on the pinion nut in small increments then measure the rotating torque. per the book you're supposed to measure the rotating torque prior to disassembly, then shoot for 3-5 lb-in greater than that when incrementally tightening down the nut. Now if your preload is out of spec prior to disassembly then don't use that value when reinstalling, instead just shoot for 20 lb-in. Regarding any [tapered roller] bearing preload, it is better to have too little preload than too much, but note there is a preload. I don't mean play.
you'll also want to inspect the yoke for burs and clean that up, and if it's grooved then you'll need a new yoke otherwise the new seal won't contact it properly and it'll leak again. Also make sure the axle housing is clean and smooth, and use sealant around the outside of the new seal where it contacts the axle housing, like permatex aviation. Make sure you use a good seal driver so the new seal is driven flush and even. And you'll need to clean the axle housing of oil so the sealant cures. GM uses #12346004 sealant which is just ptfe pipe sealant for the splines. also oil the new seal and yoke, don't install such that a dry seal is initially riding on a dry yoke. also mark the locations of the yoke and driveshaft like was said so there isn't a balance issue.
hope this helps.