I just replaced the pinion seal on my 1969's 12 bolt rear and it is still leaking. The rear was rebuilt about a year and half ago by a reputable mechanic/body man (the only outsider I'll let work on my car)who verifiably installed a new one. It started leaking almost instantly after rebuild.

I just put a second seal in myself just this past weekend (Time restraints and all kept me from taking it back to him) easy enough job, so I did it myself. The car is still up on jack stands and I'm seeing a little dribble of 90 weight form the Pinion seal.

Is there a known problem with these pinion seals? On inspection of the yoke all looks ok. It's not chewed up or grooved at all.

Any thoughts? Am I missing something? TIA


John

May not be the pinion seal itself. Could be gear oil creeping out through the splines and threads on the pinion gear.
I put sealant on the splines of the yoke and under the washer and on the threads of the pinion gear as I am reassembling it. I havent had a leak yet.

The service manual recommends putting sealer around the the seal where it seats in the housing too.

The 8460S seal that is sold for the 12 bolt is not the correct seal. The correct seal is no longer available. The 8460S is for the 12 bolt truck, but it will work in the 12 bolt car as long as you do not drive it in all the way. Leave it out about 1/16 to 1/8 inch from being fully seated. This seal goes in too far and the ruber lip goes against the outer pinion bearing. This can cause problems. Also do as stated above, use sealant inside the yoke and around the outside of the seal. I wouldn't put it on the threads though. Use Lock Tight on the threads.

Great tips guys...Thanks. The seal I put in is actually a National 8460N. It did seem like it was set too far in, I just thought it was supposed to be that way.

Here is what the '67 GM Service Manual states:

1. "Pack the cavity between the seal lips of the pinion flange oil seal with a lithium-based extreme pressure lubricant, position seal in bore the using tools...press seal into bore until it seats against shoulder."

2. "CAUTION: Pinion oil seal flange must not bottom against carrier. Press seal into carrier bore until it seats against internal shoulder - do not apply unnecessary pressure after seal is seated. To do so will destroy rubber seat and distort seal."

3. "Pack the cavity between end of pinion splines and pinion flange with a nonhardening sealer (such as Permatex Type A) prior to installing washer and nut on pinion."

That's what the book states, but when I read it the first time (and each time since!), and after reading BGH's response in this thread and it's still not clear to me how far to drive the seal in.

BGH, the book states to seat it against the internal shoulder, but not bottom against the carrier, whatever that means, and you state to leave a 1/16 to an 1/8 from seated. When I look at where the seal goes, it seems to me that if I fully seat it, it will block the passageway for the gear lubricant, so leaving the 1/16 to an 1/8 spacing makes sense. Also, would it be fair to make the statement that as long as the inner side of the seal is not touching the bearing (your concern) or the outer side is not touching the bottom of the pinion yoke, you should get a good seal? Also, do you recommend the Perm #2, or a more modern sealer like an RTV for use on the splines? Thanks in advance.

John, the only piece from the service manual not mentioned in the above posts is the use of a quality lubricant in the cavity between the seal lips. Not having a good lubricant on the lips, and in the cavity could make for some rough initial rubbing on the shaft..........of the pinion yoke.

I got the S mixed up with the N on the seal number. When I drive the seal in I check the clearance between the seal lip and the outer bearing. When there is about 1/16 to 1/8 inch clearance between the seal and the bearing I stop. This usualy puts the outer flange of the seal about the same distance from being seated. I leave a gap between the lip of the seal and the bearing because when you insert the yoke into the seal it will push the lip in farther.

I use GM 1050026 sealant on everything. Someone suggested using Teflon thread sealant in the splines in the yoke, which also sounds like a good idea.

I have the same exact prob with my 8.2 10 bolt - new seal, still leaking. Is the procedure the same?

It has the same pieces, so should be the same. If you put sealer on the splines and around the outside of the seal, and if you install the seal as BGH described, it should be good....unless you have a bad seal, or a grove worn in the yoke where the seal rides on it. Good luck.