windsor

I have a 68 with power disc brakes. The brake pedal is hard a s a rock. With the booster hooked up to vacuum, they grab hard with just a slight touch. Then the pedal is rock hard. If I disconnect the vacuum, the pedal is hard as a rock as well. There is about a half inch of play. The car does slow without the vacuum, but it is almost impossible to stop. What makes the pedal soo darn hard?

atec77

place you foot on the pedal , start the car, does the pedal lift a little ?
if not then I expect your booster is faulty / leaking .

northey

Is it the same car as you posted about on the 15/06 under"mustang brake probs, need help"?

That problem sounds like a rubber "washer" missing from inside booster.
This post sounds like booster failure.

whatever it is, you need to get an expert to fix it.