adjustable proportioning valve ?

[1968GMC]

Heres a good question. Some of you know that i'm converting from drum to disk in the front. Now if I get a adjustable prop valve, do I still need to buy a 72-up master cylinder?

[hobby67stepside]

I don't suppose this will help, but I am going with a '74 booster and master cylinder and using the proportioner that was stock with that unit. I am using calipers from '70s cars and a rear end with drum brakes out of a '71 (I think). I don't know if it will work properly. I sure hope so. Sorry for the lack of anything definite.

[tom hand]

Yes...you need to use a master cylinder that was designed for disc brakes. Drum brake mc's have a check valve that keeps a small amount of pressure in the line at all times to counteract the return springs in drum brakes. If you use them with discs it will make them drag, dramacticy reducing pad life and will make a ton of dust on your front wheels