I replaced everything lines,rotors,and made sure I got the correct Master Cylinder..also I bench bleed the mc and the whole brake system..My brakes are hard ..the car stops ok but not like a power brake system should..it still feel like the old power drum brakes I had to start with..any ideas?..My only thought is bad booster/prop valve?..that is the only items I can think of..how to test both these?

you dont mention prop valve, did you put a disc valve in?

Yes I did install a used one..dont know how to check to see if it was good before I installed it


Originally posted by FO_FDYFO:
you dont mention prop valve, did you put a disc valve in?

Are you getting vacuum for the booster from a source that is not shared with anything like a pcv valve? That could reduce the strength of the vacuum at the booster.

No the vacum is from the manifold same place as the old power drum brake booster..any other idea's?how do you check a prop valve or a brake booster unit?


Originally posted by JWagner:
Are you getting vacuum for the booster from a source that is not shared with anything like a pcv valve? That could reduce the strength of the vacuum at the booster.

Since disk brakes require higher hydraulic pressure than drums, I wonder if there is a difference between boosters: disk vs drum. If there is, then it would be expected that the disk booster would press harder on the master cylinder piston. One could go online to autozone or checker and see if the two applications take different boosters.