'87 TR Rear End

[BASSr]

OK, time to tackle the next item on this car. The rear! It is a GU6/G80 according to the RPO's and have not gotten the codes off the rear itself.

I hear a bearing noise from the right rear of the car, almost like the brake shoe is rubbing but the noise is constant (always there no matter what the speed of the car and the pitch does not change), so I am assuming that the axle beaing on the right side is the culprit. The seal in the front of the pinion drips some fluid, so this is another thing that needs to be done.

I got in touch with a local guy who does work on rears and he is quite knowledgable. Seemed to know these rears quite well and made some comments about the housing shafts normally being twisted on these rears. I know the last two owners of this car raced it but to what extent I do not know, so were they at their local 1/4 mile racing every week or were they just in the parking lot pulling hole shots!

I am going to put the car up on the lift today and pull the cover but have some questions:

- is it common for the housing shafts to be twisted?
- how much work is involved with replacing the front pinion seal myself?
- can I replace the axle bearing if that is what is needed to get rid of the noise?

Bruce

[kenmosher]

Pinion seal, if that's all it is, involves removing the carrier, so it's not trivial. Not horribly difficult either, but basically you disassemble the rear.

If you are going to go that far, it's worth it to check the carrier bearings (BE CAREFUL TO COUNT SHIMS AND NOTE WHERE THEY GO! Otherwise you'll have to set up the rear all over again.) Also, check the pinion crush sleeve and front bearing.

To do all this, you have to pull the axles and you should be able to see if the bearings are bad (and may have scored or ruined the axles themselves).

As far as the axle housings twisting, I haven't see a lot of that, but it does happen. A good welder can spot a couple welds on the tubes near the carrier and help prevent that (just be care, since too much heat will warp the tube).

In the end, it may be well worth it to have your guy just do it ... that way you don't have to worry about something being hosed.

[BASSr]

I just pulled the cover and the inside looks very nice. No excessive wear on any of the gears, fluid was very clean.

The code on the rear is 3TPG115, so it seems like this is the original one for the car!

Bruce

[turbofish38]

My experience has been if it is making that type of noise than most likely the axle needs to be replaced. OEM ones are gone so you would have to upgrade to a set of Mosers. Axle bearing and seal are easy. Just rent the bearing puller at AutoZone. Pinion seal is easy too. Pull the driveshaft and U-joint flange and the seal comes out from the front. No need to disassemble everything. Buy a new crush sleeve and make sure you put the correct preload on it is about the hardest part. Its kind of a judgement call if you need or should do anything with the carrier and ring and pinion.

[BASSr]

OK, a little feedback.


I decided to not fool around with this and finally found someone who is very knowledgeable. This guy was referred to me by a GM mechanic and he is the guy who I want to do the rear.

When I talked to him on the phone he knew these rears well so I decided to take the rear out of the car and bring it to him. When I pulled up in his shop (about an acre fenced in area behind his house with the garage add on to garage add on that we have all seen) and saw rows of axle housings outside, somehow I knew I was at the right place to have this work done. The guy, Andy, turned out to be very well versed in working on rears and a very nice guy.

After a quick visual of my TR rear, all the parts are original (axles, carrier, carrier bearings & shims, pioion yolk, and ring/pinion gears) but that the pinion seal and axle bearings/seals had been replaced. The carrier with the axles out would not spin freely and had no backlash. Gears are good. It looks like someone tried to replace the front pinion seal and reversed the carrier bearings/shims when they put it back together. The carrier bearing caps/seats show a little wear but nothing that will cause any further problems. Andy tested the axle's and they are in great shape. Andy then tested the axle housing and we found that the passenger side is straight but the driver side is out about 1/8"-3/16". That can be straightened no problem.

Bottom line is to straighten out the driver side axle housing, replace all the bearings & seals, and replace the carrier shims, and I will be set.

One other thing we found is that the pinion yolk is defective from the factory (seal surface is out of round from casting) and I got a new one from GM so the whole problem with the front seal leaking will be fixed once and for all.

According to Andy, the only way to replace the front seal is to pull the carrier, otherwise you can NOT get the right pre-load/torque. He said that in probably 60-70% of the time you might be able to get away without pulling the carrier but the right way to do it is pull the carrier.

Glad I did it this way since I know it will work roght when I get it back in the car.

Bruce

[Herbert Chance]

Anybody know if a pinion snubber will stop the noise of my car when it shifts from first to second really hard.

[Keller]

Does the noise sound line the rear tires breaking loose? If so, probably not.

Does it sound like your whole rear end jumping up and down rapidly? Then it very well might.

Pinion snubbers are best at helping with starting from a stop. I would still recommend adding a longer one. These cars already have one, but its only about an inch long.

(BTW, this should be in its own thread...)

[BASSr]

I got the rear back yesterday. The guy who did the re-build said it was in the best shape he has ever seen a GN rear in, not really beat up or abused. Just whoever tried to do the pinion seal previously screwed up by reversing the bearings & shims (left to right) when they put it back together.


I got it all back together (suspension links, springs, shocks, brake lines, filled with fluid, backer plates in, new wheel cylinders, etc) and everything went back together nicely. Did not get the brakes back together but I started it up and let it run for abot 10 minutes (to help break in the new bearings & seals) and it is so quiet compared to the way it was. I am such a happy camper now! :

Today I'll get the brakes back on, bleed them, and take it for a test drive.

Then I can get my new project on the lift ('77 el Camino). I just picked it up yesterday fairly reasonable. It has a leaking brake line (front right) but will be a nice driver. Body is pretty straight and has very little rust except in bed but peculiar that the wheel wells in the back are rust free? It has power windows/locks, swivel bucket seats (neat option), and posi-rear. Non original motor and trans (probably drop my SB 406 with TPI into it with a 200 R4.

Bruce