bought an 89 lx notch with a rear disc brake conversion i could not by any means get the brakes to bleed.... with the car off you can bleed them and get a had pedal until you fire up the car the pedal goes to the floor with power assist. i thought the master cyl was bad so i replaced it and tried to bleed them again i bleed them over and over with a power bleeder and manually still with the same result.... the car appears to have the stock proportioning valve on it for a disc drum set up would this affect the rear brakes and cause them not to bleed? also it doesnt appear that there is a residual check valve for the rear disc is this required?..... if anyone knows anything about this help would be greatly appreciated this is the only thing stopping me from driving my newly rebuilt baby thanks so much ethan