BRAKE PROBLEM WITH MY 69 CHARGER

[police1]

do you guys think it's a bad master cylinder when you have brakes but there almost to the floor when they  start grabbing hard?

[b5blue]

You can get air in the system from any of a number of places or your brake shoes could be out of adjustment, ether could do what you describe. 

[kab69440]

Usually the first sign of a MC going out is the pedal "giving" a bit when holding even pressure on the pedal. I concur with the captive air or adjustment malfunction.