OK, i have a 65 coupe with 4 wheel drums. After a little driving the break pedal becomes hard, the car still stops ok, but it becomes very hard to press. i have a stock single piston non power setup. also my brakelights come on and stay on after the pedal becomes hard. i have the brakelights wired 64.5 style with a pressure switch on the MC to activate the lights. So somehow pressure is building up in the system and causing the brakelights to stay on and the pedal to become hard. could heat do this? what would cause this? im leary of brakes, i know i need to change mc's soon to a newer style, but id like to figure this out first. oh yeah, i recently replaced rear drums only, not shoes. i dont know if this would have anything to do with it?