My '70 GS (350) came with drums all around, and I have installed discs off a Cutlass. Well, in my ignorance, I simply added the disc brakes and did nothing to the rest of the system. This setup stops the car, and I've been using it this way for 10 years. Only recently have I came to realize that my brakes need ...."something else". My question is......what? Should I add a proportioning valve for the disc/drum setup, or just what do I need to do? Thanks.....
You are correct, you should change to the proper proportioning valve. Or if you really want to dial it in get an adjustable one.
There's even more to it than that; somebody help me remember about the early A-body disc setups. The master cylinder shouldn't be unique to the disc setup if I remember right, but is the hold-off function built into the combination valve for '70, or is the hold-off valve separately plumbed into the front circuit? Either way, that function is needed for the discs. Devon
In 1970, it was separately plumbed. The distribution block on the frame was the same, regardless of disc/drum or drum/drum. The front disc cars got a proportioning valve that was located off of the master cylinder. Check out Inline Tube for the stock style hold off valve.
