I recently had some work done to the rear, just regular 20 year stuff that was due to happen. I had the U joints done and the tail shaft/rear trans seal changed, also had the pinion seal changed. My problem is the pinion seal, after the seal was changed it leaked, went back to get a second one and it leaked AGAIN!!!!. I put a piece a cardboard underneath my car and I get a quarter sized drop the next morning. Should I be concerned or is it normal to leak a little. I read a ton about the pinion nut should be marked before you take it off, something to do with preloading???. I will ask the shop if they did that because I read it can cause problems if not tighten correctly. Please let me know what I should ask before I go back for the third time. BTW I never had leaks before this was done !!!

Yes, you mark the spindle and yoke so you can put it all back together, torque at 100 lbs.ft and then tighten more till the marks line up.Hopefully that will get you about right with the preload (crush sleeve)

As for the seal did you check the depth of the first step in the bore Sometimes the replacement seals are deeper there than the case and hammering the thing all the way home so it's flush in the case will distort the seal and cause a leak. Stuff that looks simple sometimes...or often is not, there's more to it than meets the eye.

Many pinion seal leaks are caused by bad pinion bearings. Replacing the seal doesn't always fix the problem. Also, some people don't put any sealant around the outside of the seal before they drive it in, which allows the seal to leak around the outside instead of around the rubber lip. Check yours and see exactly where it is leaking. If the rubber lip of the seal wasn't lubricated then it might be getting hot and causing the leak. I've had that happen before.

I have never marked the pinion nut when replacing the seal. I usually use a new nut and torque it to 150 foot pounds. Be sure to use some red Locktite on the threads before putting the nut on. These nuts can back off after a while, especially when using the old nut again.

I just took a look under my car and it has a fresh drop of oil the size of a quarter, looks like its leaking again. I don't think he put on a new nut or locktite, can that be the problem?

....Also, how do I know if the pinion bearings are bad??. Please advise as I'm going to see the mechanic first thing tomorrow morning and give him an earful....

The yoke may have a groove worn in it causing the leak remove the yoke and if you drag your fingernail across were the seal rides and can feel it catch you may need to speedi sleeve the yoke and install a oversize seal

A new yoke is about $10 more than the sleeve kit. One thing that I forgot to mention is, when you put the yoke on you need to smear RTV sealant into the splines so that oil doesn't seap through the splines and cause a leak. Only put sealant in the splines of the yoke. DO NOT put sealant on the splines of the pinion shaft. If you do then it will shove the sealant into the outer pinion bearing and cause major problems.

Get a hold on the yoke and see if you can move it up and down or in and out. If you can move the yoke in any direction other than rotation then you have a bearing problem. Even if it moves just a very little bit you have a problem.

exactly.... or you can use teflon paste

I didn't get a chance to go see the mechanic on friday...so I was thinking.

Is is possible my pinion seal leaked out all of the gear oil prior to this fix because I never noticed any oil on the floor before . And if I had no gear oil in the diff, wouldn't I notice a noise or even failure of the rear end. Like I said prior, I never noticed noise or oil before I got this seal replaced last week.

I'm hoping the seal is only leaking and not the bearing, but still can't figure out why it's leaking, this guy has installed hundreds of seals before so I'm sure he knows what's he's doing.

One last question, if the seal is suppose to "seal" , how does a bad pinion bearing still make a leak, I mean if the seal is good, how can oil get thru??

I'm not an expert on this , just looking for answers. I go back Monday to the mechanic to check it out again.

Bad pinion bearings will allow the pinion to run off center, which will cause the seal to be too tight on one side and loose on the other. This is what causes a leak when a bearing is bad. The shaft doesn't run in the center of the seal. A loose pinion nut wil do the same thing. It allows the bearings to have slop in them and run off center.

I had the third pinion seal installed thursday and guess what, it still leaks.

So it looks like I have a problem. Before we installed the seal, I had the mechanic grap the pinion shaft and check for play. He was able to move it side to side and up and down, not much but enough to tell it wasn't tight. We figured we try one more time and see what happens...

So now the question, what should I do??, just replace the pinion bearings with a kit or decide to upgrade the gears. I want to know what is involved and the ballpark cost with repairing my 2.73 or upgrading to steeper gears. I didn't have a chance to discuss my next steps with the shop cause I had to run out.

Let me know your thoughts.

Replacing the pinion bearings requires complete disassembly of the rear end. You can do that if you want, or you could go ahead and change the gears while you are in there. It's your call.

A pinion bearing kit is going to be around $60.

A set of thick gears is going to be about $180 and a complete installation kit is going to be about $96. This will have all of the bearings, shims and other parts needed to install and properly set up a new set of gears.

Labor is going to depend on what you shop charges. You will have to talk to them about the difference in the price of the 2 jobs.

Ok thanks, I'm shutting the car down for the winter, looks like I have time to do research as I won't do a repair utill spring...

Kinda hyjacking the thread, but I have the same problem. .. replacing the seal didn't help. To boot, I have whining gears. I'm ordering gears and a kit for the bearings and seals. I was told that I could have a Borg Warner rear, and if I did, it was different than the others. How do I know? (RPO codes missing off my car). I know it's 10bolt not 9 and it's an '89 TransAM and has Limited Slip. Not sure if it's 7.5" or 7.625" but I'm told that part wouldn't matter?
..car has 3.73's in it now which tells me they have been replaced before (likely wrong and that's why it whines)

Thanks

The Borg Warner rear end is the 9 bolt. If you have a 10 bolt then it's the GM rear end. The '89 would be the 7.62.

that makes it easy. Thanks.