[crustysarge]

Hey guys, I thought I would throw this in too. I have been playing around with brakes on my 77 Trans Am after adapting the rear discs from a 98 Trans Am donor car. Much to learn about brakes, believe me. I have been experimenting with different master cylinders and have yet to get it to where I would consider "right". Anyway I pasted the statement below about residual brake pressure because it is VERY important. If you try running a drum set up Prop. Valve on rear discs that ain't too good. Do some research on the net under "residual brake pressure", you will find lots of info. A drum setup will apply 10 PSI which is too much for discs. Now if you decide to use a manual valve and the M/C is higher than the brakes, like the truck in question you should be OK.

Residual pressure valves hold a preset pressure from the valve to the brakes be it disc or drum. On some cars with the master cylinder lower than the brakes on each wheel, by holding a set pressure it insures that the brake fluid does not siphon back into the master cylinder. Also as with the case of drum brakes the return springs installed on the brake shoes will collapse the slave cylinder where you would not have contact from the shoes to the drums with just one push on the pedal. With 10 psi residual pressure held, the shoes are held close to the drums for instant braking on the first push of the pedal.