Hey guys, I might have the opportunity today to buy a rear end off an 88 IROC. Question is, would it work on an 89 RS body? What is the price I should be expecting, and does anyone have any tips or guides on installing the rear-end?

The reason why I'm replacing rear-end:

https://www.thirdgen.org/forums/tran...-8l-89-rs.html

 

Yes, it is a direct bolt in.

The IROC rear may have disc brakes, whereas your RS 'probably' has drums. If that is the case, some people recommend replacing the prop valve. Personally, I did the drum to disc conversion in my IROC, and I didnt swap prop valves, and my car has never stopped better.

 

Oh- I paid $200 for my rearend, but thats because it was a 9-bolt posi. I still had to buy new rotors, calipers, and pads, so I have alot more in the rear than that. If your putting in another drum brake rear, than expect to pay ~$100.

 

If you're swapping to discs from drums, you should consider swapping to a disc combination valve. While the drum valve will work, there is an increased bias from drums to standard discs (82-88) to PBR's (89+). There's also the parking brake cable and speedo gears (if the new rear's ratio is different) to address. Following is a 10-bot FAQ that may be helpful:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

 

Thanks to all of you guys. So it should be a straight bolt in, while it is recommended that I do some things, it is not entirely necessary. All that is really necessary is the e-brake swap,yes?

How long should a rear swap take by myself, and what tools are needed (I have plenty)?

 

Well, I have had to do it quite a few times so I can do it pretty fast, lol.

I dont see it taking more than 2-3 hours if you keep at it. Rusted bolts, and things like that will make it take longer, get some Parts breaker and hit all of the bolts and such the night before you plan on swapping.

Is the rear your getting a drum, or disc rear? Do you have drums or discs in your car now?

 

Im going from drums to discs.

 

The "recommended way" would be to swap out proportioning valves in order to correct the amount of brake fluid that engages the calipers.

BUT-
I personally dont like messing with lines having to do with the master cylinder and such, so I decided to see what happens if I dont swap it (because I had heard of people not swapping them with good results) and so far my brakes work great, my car stops far better than it ever did with rear drums, and no more spongy pedal.

Up to you, really.

 

Entirely up to the OP. That said, GM engineered different valves for different applications. Makes sense to me, for "best brake performance," to use the correct valve.

JamesC