I am having issues with my brakes on a 1981 VW Rabbit. It has a 1.9turbo diesel engine, and nothing is necessarily stock, but I’ve narrowed down some basic parameters:
The booster push rod is the major adjustment that I know makes changes. 1/4 turn one way, and the brake pedal goes almost to the floor, 1/4 turn the other way (out) and the pedal feels great, brakes work wonderfully with great power assist, but the brakes drag (I can hear it when I push it and the wheels heat up). When the brakes drag, they only drag when there is vacuum pressure. If I take the vacuum line off or turn the engine off while rolling and pump out the pressure, the drag goes away completely.
Is the booster push rod adjustment supposed to be so sensitive? If so, why? It seems like pushing down slightly on the pedal would be the exact same thing as turning the adjustment out… I am missing something in the theory of operation, and could really use some help understanding this one.
Things I have done: I have a brand new, high end master cylinder, plenty of fluid and the level stays good, vacuum pressure is solid. I have pumped the brakes, and it did seem to help once, but it has started to seem more like a random item…