CELEBRATING 20 YEARS!

Quick question. If I'm converting the rear to disc and I have the Disc/Disc proportioning valve, do I still need a Disc/Disc master cylinder?

I'd guess that having a matched master/prop valve/caliper volume "fully engineered" would be best and will get the most out of the system, but I think there's hundreds of guys who have seen a good improvement switching to rear discs and just doing the prop valve... Some folks much smarter than me might have a different take, but I don't think you "Have to" switch by any means. And it might depend on which rear brakes you are using as well.

There many options, I want to do this soon too, Im thinking 8.8 w manual adj proportial vlv. Check utube

There many options, I want to do this soon too, Im thinking 8.8 w manual adj proportial vlv. Check utube

Usually, you have to upsize the master cylinder depending on what master cylinder you are using.

1978-1981 "g-bodies" have 24mm strait bore master cylinders used with the factory power booster.
1982-1988 g-bodies have step bore master cylinders with a larger bore 1.25+" for volume that necks down inside the bore to a smaller 24mm for higher line pressures.

If you have the step bore master cylinder, it may work fine depending on what rear caliper you run.
If you go with fairly large rear calipers, you will most likely need to upsize your master cylinder to a 1.0" bore master cylinder.

What rear caliper are you plan on using?

I'm getting a Currie crate 12 bolt rear end with Ford 11" disc set up on it. The set set up is a Ford Explorer rear disc. Not sure on the specs. Since they're an OEM set up, I think I'll be fine with the stock Master. Thoughts?

You'll need a disc/disc master cylinder and appropriate combo valve. Good luck!