Going to go pick up an IROC disk break rear for my RS this weekend. But before I do the install have a few questions. First one, should I replace my master cylinder with one for an IROC? Is there any difference in master cylinders for a drum brake rear and disk brake rear? Or would it be ok to just install a Wilwood (or similar) adjustable proportioning valve?

Thanks in advance for the help.

David

 

It depends on the disk brakes that you get.

If they're the aluminum PBR calipers, then their hydraulic requirements are similar to those of drums, and the MC and PV will work. In fact those parts are the same in 90-up cars with those brakes.

If they're the crappy cast-iron Saginaw calipers, then their hydraulic requirements are quite different from drums, and the MC and PV will probably need to be changed. Additionally, the calipers will probably need the recall kit installed, and doing the PV mod would probably be beneficial.

Since you say "IROC rear", and the vast majority of those were Saginaw-equipped, odds are you'll need to do some other work besides just the rear swap.

 

What other kind of work do you mean? According to the guy I am buying it from, the rear has 3.73 gears in it already and the posi unit was reworked. Going to paint the rear with POR 15 and put a different cover on it. Along with new pads and maybe rotors. Do you know where I can find slotted or cross drilled rotors for this rear?

Thanks for the help.

 

The paragraph right before the one you quoted.... since nearly all IROCs were produced before the changeover to PBRs, nearly all "IROC rears" have Saginaw calipers; so you'll need to change the MC and PV, and install the caliper recall kit, and probably do the PV mod, if you want them to work reasonably well (as well as they can that is).