Ok, so I've been looking for a rear end for over a month now for my 91 Z28. All I'm looking for is 3.42 posi with drum brakes and I'm finding it impossible. Well I need to get my car running so now I will just spend extra for a 3.42 posi with disc instead.

My question is: what exactly are all the parts I need to change this 91 Z28 from drum to disc? I've read many posts and read many different things. Does anyone know for sure?

And do the parts I need differ depending on what year the disc rear is out of? Should I stick with finding a rear from a 91/92 only?

Also, if you have one to sell and you are somewhere around Sacramento, CA....then I'll buy it.

Thanks very much to anyone who can help out.

Bugsy

 

I had a 3.08 drum out back and swapped in a 3.42 disc rear end. I gotta an 86 so I don't know what changed by 91/92. All I know is that everything bolted right back together and I did install a disc proportioning valve-just because. Like you I read other posts that said you did'nt have to, but I got it for free and figured what the hell. I did take out all the bleed screws and replaced them with self-bleeders, just loosen and pump like a mad-man, then tighten back up, best convenience items I ever bought.

 

IHI,

Didn't you have to change the ebrake cable and the brake lines?

 

Mines mostly track use so E-brake went bye-bye, and the disc rear end already had hoses going to caliper coming off the T on the rear end housing, so I just unhooked the "main" line from the T on old rear and hooked it back in on the new rear.

 

anyone else have any knowledge in this area?

thanks

 

AFAIK the MC and prop valve are the same in those years for drum or disc. So the rears should just interchange directly without having to change anything else. Go look them up on www.carparts.com or www.napaonline.com if they only list one MC and prop valve, then they just interchange.

Definitely find a rear from 90 up; the older ones will have different disc brakes, and they're the grossly inferior ones; and they require teh different MC and PV. Stay with the newer rear.

I'm not sure about 91 cars and the parking brake cables; but the 91 or 92 disc rear I have in my 83 just hooked right up to the 83 parking brake thing in the car like it was meant to, I hardly even had to adjust it, and it works perfectly. I did have to deal with the metric/standard thing on the hydraulic lines, but that was easy: I just got the end off of the 91 car side of the steel line, the last 6" or so, cut that much off the 83 car, flared them both, and used a union fitting. Again, works perfect.

 

Unless you're set on rear disc.....

Try looking at V-6 equipped Camaro and Birds.

They are all over the yards here, and alot got 3.42's





HTH

 

Very very few 6-cyl cars got posi.

 

Thanks for the replies guys. RB83L69, I think I will take your advice and look for 90 or newer rear ends only...i believe the 90 iroc had the borg wagner 3.45...not sure if that is disc only or not though....or i'll take any 91/91 3.42 disc posi. I'm just having problems locating one and so is the gm recycle yard. I guess I'll just have to keep waiting.

Thanks people.

Bugsy

 

Actually I don't think any 2.8/3.1 v6 got a posi!

Bugsy, why not just convert your current rear to a 3.42/posi? You've got 28 spline axleshafts so you can buy the take-off posi from http://www.slponline.com . Then just get 3.42 gears and you're totally set.

Know what I spent to swap in an '84 3.73/posi/disc rear??? Over $600. Axle was $150. One rear caliper was $60, I was able to rebuild the other one myself with a rebuild kit ($12). Got the junkyard car's prop valve and m/c for $15, turned the m/c in as a core for a rebuilt for another $20. Painted the axle with http://www.por-15.com 's Super Starter Kit (came out great!!) for $20. Changed the rear axleshaft bearings (aka 'rear wheel bearings'). Had to bend & flare a new brake line after snapping one at the fitting. Got new rear caliper bolts and slides and bushings and brake hoses (two hoses on 82-88 rear disc axle).

After trying to get the brakes to work, kept getting a "BRAKE" warning light and no brakes. M/c was bad, so I returned it (after a week of disbelieving that I was the 1 in 100 sucker to get a bad rebuilt m/c), new m/c worked much better. Still had no rear brakes, but at least I had front brakes again. Bled, re-bled, bled some more. (Hands turned nasty from overexposure to brake fluid.) Found out about the 82-88 rear disc recall. Bought the kit from gmpartsdirect.com for only $40. Took the rear discs apart again, rebuilt them again with the rebuild parts. Bought a Phoenix V-12 Injector ( http://www.brakebleeder.com ) and it made the bleeding process a 5 minute deal!! I highly recommend this tool!! I wish I had it in the beginning!! Anyway, finally, I got rear brakes.

Then I was so happy, I forgot to readjust the emergency brake levers. My rear brakes were dragging all the time, and completely confused the posi to hell. (In '84, the posi was actually an Eaton Gov-lock locker, not an Auburn posi.) So guess what? The gov-lock died it's usual, common f-body death, rendering my axle useless. Can't find 28 spline axleshafts anywhere in NJ junkyards.

Oh- yeah- I found one. In the mud, on a V6 car. Snapped the f'ing pinion lock bolt, tried a cold chisel and BFH but couldn't get the axleshafts. Oh I wish I had my air tools in that junkyard. So now I'm back on another junkyard axle, a 3.42/open/drum from an '88 V6 f-body. And looks like it'll stay that way until I can either save up for a brand friggin new 26 spline posi, or, find 28 spline axleshafts that aren't twisted up to hell.

Oh and did I forget to mention that I went through a 3rd master cylinder? Yep, the 2nd master cylinder tore a rear seal. So I opened it up to put a rebuild kit in- and found that the bore was trashed. Had to return it again for another. Actually, no, I didn't. I just remembered that I never returned that m/c for the $15 core charge- DAMMIT. Think they'll take it back after 2 years? Haha... well, anyway, so that 3rd master cylinder cost me $30.

So you can try hooking up a rear disc axle, sounds like you'd rather keep the drums. But I think you'd be better off spending your coin for the slp posi and new gears. That's $300, excluding labor for the gear setup, which should be $200. Meanwhile, I'm out over $600 (if you count the V12 brake bleeder, which I dont) and still dont have a good axle.

And I thought it was going to be a budget swap.

 

Here is a rear end for you...



Sorry, could not resist.

 

LMAO!!!!! :sillylol:

 

RU-QWIK, what kind of lube do you recommend for that rear?

(Couldn't resist, either!)

 

K Y seems to work well.. You can get it at most retail stores....

 

Wow!!

(THUD!!) <<--sound of Ed's jaw hitting the friggin' floor.