1968 Dart Proportioning Valve Plumbing? Which lines go where?
I wonder if I could just get a proper disc/drum style master cylinder and not use a proportioning valve?
There are only three things that separate a disc/drum M/C from a Drum/drum.
1) the sizes of the reservoirs,
2) residual valves, and
3) the size of the piston.
There is NO proportioning done in the M/C.
If your car has 4 same size tires on it, then you MUST have a P-valve.
And the reason is;
Disc brakes are NOT self energizing, drums are.Therefore;
Disc brakes require much greater hydraulic pressure for the same rate of stoping. This much greater pressure , with no control to the rear, will cause the rears to lock up much sooner. When the rears are skidding, traction is lost, and there is nothing to keep the back end in the back, so it tends slide out sideways and spin the car around. Therefore, the rear drum brakes have to have some kind of brake-force reduction, or increased friction to the road.(Bigger or stickier tires)
Drum/drum systems achieve rear proportioning with reduced shoe size, and wheel cylinder size.
The rear brake system is completely independent of the front. They are just operated by the same pedal. The rear system is actually not even connected to the pedal and is normally operated by a hydraulic connection inside the M/C.
The Chrysler P-valve I showed is actually a C-valve,or Combination Valve, in the which;
The upper portion to the front brakes is just a distribution block.
The lower portion is the Proportioning system to the rear brakes.
The inbetween portion houses the shuttle valve, that turns on the brake warning lamp, when either brake system fails.