pinion yoke seal replacement questions - Third Generation F-Body Message Boards

Saculia · 09-22-2009, 12:47 AM

Hi,

My 91 formula has recently developed a slight leak from the pinion yoke seal. The leak has not gotten that bad yet, but some oil has been thrown on the drive shaft tunnel and also the exhaust. I am planning on replacing the seal this weekend before I lose any more oil.
My car has the 3.42:1 ratio posi disc rear end. I have been looking for a replacement seal and I have been finding that two seals have been listed for our cars for 91. One is for a 7.625" and the other for a 7.75" ring gear. I find this a bit confusing, since I was under the impression that all 10 bolt rear ends from 90 to 92 came with the same size 7.625" pinion gear. Is this correct? Is this the pinion gear that is in my car? I just want to make sure that I get the right size seal before I take my car apart and find out that I have the wrong part.

Also, what lubricant should I use on the new pinion seal to prevent the pinion yoke from the burning into the new seal? Would some high temperature grease do the trick, or do I need something else?

Finally, my manual calls for tightening the pinion nut to 1/16th of an inch past the mark where its original position with respect to the yoke was. Would I need to do that if I use some thread lock on the nut?

Thanks in advance for all of your input.

big gear head · 09-22-2009, 07:52 AM

The 7.75 is the 9 bolt Borg Warner rear end. If you have a 10 bolt then you have the 7.62 rear end. I just use gaer oil or regular grease on the seal and I haven't had any problems with that. I wouldn't worry about marking the nut. I just torque them to 150 foot pounds with red locktite. This has worked fine for me for many years.

Saculia · 09-22-2009, 10:31 AM

Thanks for the reply. I will torque the nut to 150 ft lbs.