i have a 92 RS with rear drums and 2.73 gears. in the garage i have a 3.42 posi with rear disc brakes out of my 83Z28. one day id like to put the Z28 rear end in my RS and convert it to disc brakes. what all is involve in this brake swap?

 

It pretty much bolts right in.
You'll will need the proportioning valve and maybe the master cyl as well.
The brake lines did change from SAE to metric around 84 I believe, so that will cause some problems.

The brake line at the proportioning valve, for the rear brakes, may come in from a different angle.

You'll need the e-brake cables for the disc rear.

I put a 87 9-bolt disc rear in my 82 Z.
I also swapped all the brake lines to get around that SAE/Metric thing, and the different angle on the proportioning valve deal.

Even with the correct proportioning valve for the rear disc, I had to modify it to get enough press to the rears.

You'll probably have a hard time getting the parking brake to work well. Hopefully you have an auto tranny.

 

Well, the only thing you REALLY need is the e-brake cables (well, brake lines that connect are good too if there is the SAE vs metric problem).

I'm running with completely stock (92 RS) master cylinder, prop valve, etc. The only thing I replaced was the rear axle (just like you've got) and the e-brake cables. The rear brakes do function, although I will lock up the fronts first (my tires aren't helping... 225's on the front and 255's on the rear)

As far as e-brake cables go... By 92 (not sure what year this changed) the center cable from the e-brake handle has a self-adjuster IN THE HANDLE mechanism. This is far superior to the manual adjustment in the tranny tunnel that older cars (84 and earlier for sure) had. This also means the e-brake cables don't have to be the perfect length, as the self-adjuster can handle a little bit of variation.

I believe the brake cables that I settled on were for an 87 with drums. 87 was kind of a bastard year with lots of mix and match parts. At some point around then the mounting points for the e-brake cables moved farther down the tranny tunnel. So plain old 83 disc cables won't work (too short I think). The stock 92 drum cables you've already got are way too long. I will find out for sure what cables I used and get back to you (of course that is the one detail I forgot to write down :-) but the friend who helped me will know). We had three sets of cables on hand and only one set worked (and on the passenger side it was VERY tight, but it did work).

 

Oh and by the way, if the rear calipers you are considering have NOT been rebuilt with the recall kit (GM p/n 18019028 about $35 from gmpartsdirect.com, one kit does both calipers) you absolutely SHOULD rebuild them. It isn't terribly difficult to do the rebuild and the self-adjuster in the old calipers (the one that allows the e-brake part of the caliper to work) fails VERY often on the old-style (non-1LE) calipers. Since it also adjusts the piston out to compensate for pad wear, if the calipers haven't been rebuilt they stop working right fairly quickly.

This only applies to non-1LE brakes.