Sbarnhart22270

I will state up front that I dont really know anything about rear axles. I have a 90 camaro with a posi/drum combo. I know where there is a car with a ltd slip/disc combo. My question is can I put the disc axles in the posi rear end and have disc/posi? Do I need a whole new rear end for discs or is there a reasonable brake swap for just the rear? I have also heard that a 4th gen rear will fit. You guys know way more than me so what would you do? My rear end is out of a TA GTA supposedly and I dont really have a reason to doubt it , but I havent actually checked the numbers.

jmd

iTrader: (4)

Cars over 20 years old means it makes sense to:

Stop guessing.
Pull the rear cover to change the gear oil.
Count ring & pinion teeth so you know what you actually have / stop guessing.
Look over the differential carrier to see what it actually is / stop guessing.
Take pictures so if you have questions you can post pictures and stop guessing what's really inside.

High points of 10-bolt rears:
The flanges at the ends are 3-point for drums to mount the wheel cylinder & backing plate. This is for all 82-97 10-bolt drum rears.
Disc rears had 4-bolt flanges to mount the caliper brackets.

Carriers commonly available which you may find in your adventure:

Open. Not posi, not limit slip.

(Posi(traction) is just another term for limited slip.)

Cone friction limited slip; "Auburn" style. Widely regarded as non-rebuildable. They work until they don't. I have one w/ 150,000+ on it but others aren't so lucky.

Gov-Lock. These have inertia of differently spinning axle speeds cause a gear to lock the sides together. Usually more commonly found in GM trucks. And not ideal for a street car; avoid them.

Clutch friction limited slip; "Eaton" style. Rebuildable but not common in production; you'd have to buy aftermarket. A good option for street/strip.

"Torsen" or Zexel-Gleason gear bias. These were an SLP option for 1998. These were standard in V8 f-bodies 1999-2002 (the SLP option became an Auburn.) For a nice driving street car, these are probably your best bet.

Also:
Axles from 82-88 were 26 spline in 10-bolt rears. Some, but not all third gens around 1990 went to 28 spline.

26 spline iron caliper auburn posi rear? Skip it.
28 spline aluminum caliper limited slip third gen rear? Go for it.

Re: discs:
If you haven't ugpraded front brakes yet, do that first. WAY more gains to be had from front brakes.
If the calipers are the iron caliper 82-88 style, they're not worth the time to swap. 89-92 are what you want.

Once you figure out what gear ratio you have and whether you have a limited slip diff., you can better make a choice on purchasing a rear that may or may not benefit your car. Usually, you wouldn't want to go from a 3.23 to a 3.08 or lower (for example.)

Now, go read the FAQ on 10-bolt rears at the top of this forum. And realize some third gens got the 9-bolt rear instead of the 10. It too, warrants reading.

big gear head

Don't call a standard differential a limited slip. That is completely wrong. Posi is Eaton's trade mark name for their clutch type limited slip differential. Posi and limited slip are the same thing.


For a street car the rear disc upgrade isn't much of a benefit. If you were road racing then you would need good disc brakes for the rear. You also need to upgrade some of the other brake components when doing the rear disc swap.

Sbarnhart22270

So basically a rear disc swap isnt worth the hassle. That gets right to the heart of the matter.
I am learning about repairing this car as I go. My confidence level isnt the highest and if I screw something up I want the money to have someone else fix it. The motor is good so far(rebuilt), good suspension(new), exhaust(new) and some body work.
I am doing the interior myself and then trans(have it looked at,no probs yet), then rear end(also no probs yet).
You guys know so MUCH about these cars, I just wanted to see if my idea would work.
I am going to get some stuff off of a parts car and wondered if getting the disc rear was worth it.It is kinda far away so I figured while I was going I would check it out.
Thanks, I will concentrate on better fronts instead.
Maybe with more research I will mess with the rear.
Again, Thanks.

big gear head

Forgot to answer your other question about the 4th gen rear. They will bolt in, but they are about 4 inches wider. Many people have used them with their stock wheels and had no problems. Others have used wheels with more back spacing to get the tires back under the car again. The '98 to '02 are the most desirable because they had the Torsen differential instead of the Auburn.

formula00ra

iTrader: (1)

I think the rear brake swap is worthwhile. It will cost you about 800 bucks to get all the parts and have the calipers rebuilt. Once installed you will find that the disc rotors won't fit over the drum axles. Just take the rotors to a machine shop and tell them to open up the part that mounts to the axle a quarter of an inch and they will fit fine.

fullsize fun

I just pulled a rear from a 3800 V6 car with the optional 3.42 and g80 and its an auburn unit. the 98 V6 car next to it was a 3.23 with no posi.

L67ss

RPO stickers are your friend. Also 98+ rear discs aren't a hard swap