Proportioning valve or no for 65 Dart disc/drum brake conversion.
I have taken several Combination valves apart, and concur that they are just a hold-off valve . The idea being exactly what
@C130 Chief said in post #18. It's just a valve with a spring. I can't speak as to the pressure required to blow it off tho.
And IMO, Chief is also right about w/c size being a better anti lock-up plan.
I’m guessing I don’t need a proportioning valve. Am I wrong?
The answer is yes and no. With four same sized tires and 10inch rear drums, you may get premature rear wheel lock-up, so in that case yes you are wrong. Premature Rear Wheel lock-up must be avoided at all costs because as soon as the wheels stop turning, the back-end is already planning to come around , and you may have only milliseconds to avoid a spin-out or a collision.
But if you have bigger tires in the back, you may be able do better proportioning with smaller brakes and or fine-tune with w/c size.
For example; I run NO Proportioning at all on the back of my car.
It has 10x2 drums on the back, 7/8ths w/cs, and 295/50-15s.
on the front are KH 4-pots and 235/60-14s.
The M/C is a 15/16ths, and yes I run a large single-diaphragm Booster.
When I brake hard, it's like I imagine it would feel to throw out a 'chute at speed; the car just hunkers down and stops without any drama. Because it works so well, I sometimes drive stupid because I know the brakes will be there for me.
I gotta admit tho, that she burns off more than double the sets of rear shoes to one set of front pads..... In other words, the rears are doing a lot of the light-pedal work. And I like it that way, cuz in 1999 when I built the car, there was no way of knowing if I would ever be able to procure another set of rotors. So I stocked up on pads at least.
