I have a 59 Chevy Apache that I put disc on all four corners with a dual chamber master and boster. I used residual valves front and back. Do I need a porportioning valve or will it be ok without? It is powered by a 383.
The rear brakes should not lock up before the front, or the car could swap ends in a panic stop.
A proper master cylinder will allow the rear brakes to come on slightly before the fronts, and then the braking power is greater on the front to prevent the rears from locking. An adjustable proportioning valve will prevent rear lock-up in maximum effort stops.