O.k., I've been searching for about 3 hours now, and have yet to fully answer my question....

I've swapped my front brake system to C5's (thanks EBMiller), and I've gathered up almost everthing for my
LS1 rear swap. I plan on running a 98-02 Z-28 master cylinder, but what should I do for a prop or combi
valve?

BTW: car is an 87 Z-28 disc/drum car, and I'd really rather
use an o.e. valve than an adjustable, and preferably one
that doesn't require cutting/flaring lines....will the 91-92
prop valve bolt right in and work keen?

Thanks ahead of time.

 

 

I am going through the same thing right now, and had planned on replacing master cylinder, combi valve, and lines with 4th gen parts. Might be a little more labor intensive, but everything should fit and work correctly.

 

I think I'm going to do the 4th gen master and Wilwood prop valve....I'm thinking the C5 brakes will be greedy and
try and way more stopping than the rears....

 

i was talkin to a fellow member on this and he has a 91 rs with 87 Irocz rear end and brake lines. he tried using the stock 91 proportioning valve on the 87 lines and it does not work.

 

I swapped the LS1 brakes onto my 91 Z(original rear drums) . I ordered a new prop valve from GM for 4 wheel discs . I wasn't happy with the feel of the pedal. There was an article in Chevy High Performance putting in an adjustable prop valve last year. I put the original prop valve back in with the mods they said in the article(remove the rear spring and seal) and changed the master to an LS1 master . With an SSBC adjustable prop valve the brakes went from OK to Awesome.

 

From Dan Burke's page:

1LE Combo Valve (proportioning valve)
14089496 1989 1st design: M1.0 tube nut threads (For 1982 - early 1989 applications)
10136840 1989 2nd design: M1.5 tube nut threads (Late 1989)
10136840 1990-'92: M1.5 tube nut threads.

JamesC

 

The valve I got from GM for a 91Z with 4 wheel discs is 10164112 . That was the only one available .If you have a 4 wheel disc valve that doesn't fit you can switch the guts out of it into the one that does bolt up . I did this before trying the new one from GM . Let me know if you want the 91 combo valve as I don't need it .