First read the tech article on this site
https://www.thirdgen.org/newdesign/t...hgenrear.shtml

I wrote another similar thread before and decided that since i just did the swap, i would clean that post up and add more info and pics. This is what i know about the rears and swap from lots of time searching and my recent experience.

The 4th gen rears retain all of the third gen stuff, all shocks/springs, panhard bar, lower control arms and such.

If you lower the car, get an adjustable panhard bar to recenter the rear… if not it will kick out on the driver’s side. Mine did that with an eibach pro-kit.

LT1 and LS1 A4 cars had either 2.73 or 3.23 rear (gotta check that out) and T56 cars had a 3.42. The LS1 rear is preferred in a lot of cases because of the brakes that usually come with it. They are pretty big at 12inch and big 2 piston calipers and work good. Up until '99, the 10 bolts had Auburn posi units..(from the best of my knowledge) which is a clutch type posi that needs limited slip additive. 99+ Ls1 cars had Zexel Torsen differentials which are great for strip performance. Although some SS model cars from 99+ did have options for the Auburn unit. Zexen diffs dont have clutches which can wear out in a short amount of time. Just another advantage of the zexel differential.

The 93-97 4th gen rears are 3.8" wider from hub to hub so the stock thirdgen wheels will stick out some. A lot say that its even with the fender lip so its not all that bad. Some stick out abit past. the 98+ rears are abit shorter, at about 3.5 inches wide they say, but my measurements are showing more like a 3.125 inch difference. LS1 rear is about 64 3/4inch long and 9 bolt was 61 5/8. Below you can see my pics, its even with the fender lip.

Also, the rears are available with traction control or without out it. These are called 4 channel rear ends for traction control, and 3 channel rearends without traction control. Since thirdgens don’t have ABS or traction control it really doesn’t matter which type rear you get performance wise. However the brake lines on the rear will be different. The rears with traction control and abs have split separate lines and don’t connect to a T block like the 3 channel and factory thirdgen disk brake rears...so if you get a 4 channel, you’ll want to run new hardlines from the calipers to a T block on the rear end, just like factory thirdgen disk brake cars have. You should be able to reuse your factory disk brake cars rubber line and Tblock and just screw in the new hardlines to the 4thgen calipers. Several members have done this. (82-83 cars might have different fittings for the hardline on the car from what I read, so you might wanna check that) Just measure the new hardline lengths, which should be about 18-20inch on the drivers side and 26-30 inch for the passenger side. Check which type fitting ends they have. i'm not sure on this one. Also check to see if your factory lines will work…I have heard it works as well.

3 channel rearends have brake line setups like our thirdgen cars. The lines run from calipers and meet at a T block on the rear and the rubber line from the T block just screws into the factory thirdgens hardline fitting. My rear was a 4 channel but I had 3 channel lines put on. My car is a 89 with factory PBR calipers and 9 bolt rear end. LS1 rear was direct bolt on from suspension stuff to the brake lines.

For the drum rear to 4th gen conversion, you can use the stock 3rd gen master cylinder...some have even used the stock-proportioning valve with out problems. However it wouldn’t hurt to put in a disk rear proportioning valve or an adjustable one from summit racing or wildwood. I’d recommend it. You will need the proper brake lines from the calipers to the T-fitting at the rear. You should be able to keep everything factory from that fitting forward just like the disk brake cars above. This comes from the research on this site I have done, so the hardline fittings on the drum car must be the same as the disk cars. The rear brake lines and the parking brake are the only things you'll need to modify when swapping to a 4th gen rear

Now for the stuff that don’t work….like I just mentioned, the only thing that isnt a bolt in deal is the ebrake cables. For that to work, you need to make a bracket to hold the 4thgen cables to the top of the trans tunnel.. or get different cables and mod them to work

LS1 98+ rears go here for Ebrake cable info. It covers part numbers, custom brackets and such. Basically, The Bendex P/N# C1621 are the ones to get, but I guess they are discontinued? So use Tru-Torque# C94597 which are 1460mm long. Page 2 of the bottom link goes into good detail on these cables and mods. Also you can use the stock LS1 cables if you mod them as mentioned in the link. I am not running cables yet, and probly will be buying the ones mentioned.

https://www.thirdgen.org/techbb2/sho...=&pagenumber=1

If you have a 93-97 rear, go to a parts store like advance auto, or pep boys or whatever, and ask for e-brake cables for a 90-92 camaro with rear discs. this will give you the right cables. you'll need two. The 90-92 F-bodies used identical rear disc brakes as the 93 to 97 4th gens. A lot of ppl use the 91 or 92. Get the first design, as there are two I believe.

Few pics at the bottom of this thread… describing stock wheels sticking out

https://www.thirdgen.org/techbb2/sho...h+gen+rear+end

Some info on beefing up 10 bolt rears

https://www.thirdgen.org/techbb2/sho...h+gen+rear+end

 

And heres my installation pics! Hope it helps. It was really easy to do. Basically you get the car on jacks and start disconnecting stuff. I started with the torque arm, then driveshaft…then unbolted the brake line from the hardline on the body. Then control arms/shocks/panhard bar and the rear came out. Then just reverse process on install. The rear fit good and my brakes work great! Didn’t change a thing with the proportioning valve. Took me about a day to do it, but I’m a slow worker with no power tools.

 

and more can be found here as i dont think i can post more than 3 pics

LS1 rear end installation pictures

 

Sweet write up! I'll be doing this swap during the winter months with a '95 Z28 rear. Comes with brand new Auburn posi, Strange 28 spline axles and 3.73 gears, LPE girdle, all new parts, welded tubes, glass bead calipers all for $700! I can't wait..

Looking at some of those pics from Zepher's post, I'll be needing new rims as stock GTA's kinda look weird

Btw, your car looks sweet!

 

I've seen some people talk about welding the axle tube to the differential. does it really help all that much, and what does it entail. a bead of weld all the way around?

 

apparently it keeps the tubes from flexing at all, but i'm not sure how proven it is. it makes sense tho and since its not all that hard to do you might as well. its just a bead all around from what i seen

 

Makes to me too. pittsburg, haha you should tell you football players to wear helmets