I'm neck deep in a rebuild that I've had my local mechanic working as a side project during his slow season. I've had the guts ripped out of a wrecked '88 GTA (engine, tranny, suspension, wiring, rear end, the whole 9 yards), and shoved into my '90 firebird that finally burned up after 240,000 miles of awesome driving. The firebird was the first car I'd ever driven, so perhaps that can partially explain the insanity behind doing (and having a third party do) $8,500 worth of rebuilding to a $1000 car.

Ok. Maybe not.

The rear end sounds like grinding metal (really bad brake disks, maybe) at all speeds, especially on the highway, and makes a violent, intermittent groaning noise at low speeds. Applying light brakes stops the groaning noise, and it stops once I get past around 25 MPH, but it still sounds like there's a cement mixer under my car when I'm driving down the road. An inspection from a second mechanic confirmed that the gear oil in the differential is black, and looks like a Goth Barbie glitter kit from all the metal filings.

I know the rear end is probably junk, but I was wondering if I could pick your brains, and try to get an idea of what I'm going to have to replace, and how much an honest mechanic would charge for it.

 

it'd be hard to guess without knowing what the problem is. take it apart and figure out what you need.

 

Sounds like the bearings and galled and pitting from the 'glitter kit'. Just as ede said take it apart inspect everything.

 

These rear ends are all over the yards. Before sinking too much into what you've got I'd look around for a complete replacement. The good parts (brakes) can swap over to another. I wouldn't necessarily consider the stock posi-unit, if so equipped, to be a 'good' part.

By all means open yours up and look first but by the time you swap bearings, etc. you can easily top the $175-250 a decent used unit should cost.

 

Is it a 9 bolt or 10 bolt in your car now? Would be easy enough to swap out the entire rear end with a wrecking yard replacement. Know what you want before you start looking, take the rear end codes with you to cross ref against the code stamped on the axle tube.

 

I am going to guess that you have a 9bolt rear (common rear on the GTA's and you say 3.27 in your profie), and if you do, they are very pricey to rebuild.
I am not sure what wheels you have and if you had planned on getting new ones, but I would recommend a complete 4th gen rear (98-02) out of a 6 speed car (3.42 gears standard) and get a pair of wheel adaptors and a set of 4th gen offset wheels. You can get all of the above for less than $600 if you find some deals.
Rebuilding the 9bolt (which will be stronger than teh 10bolt) will run around $1200 if you have a shop do it, and around $900 if you do it or have a friend do it.

 

Will the rear discs on my setup swap over to a unit with drums on it, or will I need to score a unit with rear discs as well?

 

Thanks for the advice. I was hesitant to try for a junk yard rear end, just because these type of cars get the crap beat out of them so bad. I don't want to put down my problems just to pick up someone else's problems. But I'm getting a general consensus that JY rear ends aren't that bad. I'll definitely keep that as an option on the table. Even I can turn the wrenches necessary to do that kind of swap.

 

It's easier to swap over to one that originally had discs but the drum rear can be modified. There's some threads on it somewhere here.

Always open the cover of any JY unit you look at. Provided the oil is clean, the magnet is clear, pinion is tight and no leakage around the axle seals you'll probably be OK. Ratio is stamped on the ring gear in teeth count. A V6 rear end is usually a safe bet, doesn't get beat on and should have good gears. I figure for a build like yours you'll probably want an aftermarket limited slip anyway, so open vs. factory posi shouldn't matter.

 

OK, so I found out that it is a 9-bolt, and it's the austrailian built flavor. I can't find a replacement or parts for it right off hand. Does anyone know where I can go to find parts?

 

Parts for the nine bolt are going to be double (or more) than for the ten bolt and 10x as hard to find. Check: https://www.thirdgen.org/forums/tran...highlight=bolt

'Course by the time you add up the money for the parts (if you need to replace anything major) you may be at, or over, the cost for a used 10-bolt. There's some used 9 bolts out there too. I picked up mine for $175 'bout a year ago.

I recommend a used later model, 28 spline 10-bolt with an aftermarket limited slip. If you can't find a good used 9 bolt. Make sure you open the cover of any used rear end. I went to a local yard to look at a used 3.42 w/discs. They wanted $225 for it. Pulled the cover and it was a gov-loc with a fuzzy magnet. Saw the 9 bolt next to it, it was clean and the posi was tight. They only wanted $175 for it. I think that 3.42 is still sitting there.

 

It's looking like it's just the posi unit that needs love. It doesn't turn worth a crud. Can those things be rebuilt at all?

 

Also, if I do decide to go with a 4th gen rear end, would I be able to use my 16" hi tech wheels? I already treaded them, and I'd really like to keep the stock looking wheels. Plus, this car is a bit of a sleeper since it looks like a bone stock firebird without the ground effects, hood, or spoiler that a T/A gets.

 

One of those sites is the old nine bolt site with info on rebuilding. Read some talk recently about buying replacement cones, etc. from Aus.

Don't need a 4th gen rear, they're a hair wider anyway and no stronger.

 

I found the factory in Aussie. I'm going to contact them, and see what it would take to get parts, or a replacement unit.