I did a disc conversion on my friends 70 Coronet R/T. Stock 70 pin type calipers and master. Car doesn't want to stop even at idle. Pedal feels normal until its about half way down. Then it feels like a brick is under the pedal. You can't move it further. All stock stuff. Pedal linkage is correct,tried 2 boosters,2 master cylinders(1 1/8" and 1"). Rear wheels can be turned by hand with brake applied unless it has extreme pressure is applied. I actually have this same condition with a 66 coronet. It has 4 wheel drum with a converted dual master. Otherwise all stock.
Any ideas?
Doug