A couple of questions, what kind of a car do you have/??
Does it have 2 or 4 wheel disc brakes?
If you "pump" the brake pedal, does the pressure come up??
OK, If you have 2 wheel disc's, I'd try adjusting the rear drum brakes.
Also, Brakes need to bedded to the drums/disc's properly and the pedal may come up after repeated use. (transfer of brake material to the rotors or drums)
Also, brand new disc brake pads contain an inordinate amount of glue and resin. Burnishing the brakes makes them last longer and work better. Burnishing is a series of high speed stops, to the point that the brakes begin to smoke. The smoke is the product of the resins burning from the pad (a good thing)
If you pump the brakes and the pedal increases in height and firmness then the brakes need to be bled, Start with the furthers brake from the master cylinder and work towards the closest.
Another problem that has occurred is that the master cylinder rod is mis-adjusted. by turning the rod, it may increase pressure but be very careful as you don't want to put and un-due pressure on the M/C thus causing brake drag.
4 wheel disc's have a tendancy to feel soft so don't worry if the pedal feels light, the main outcome is that he car stops properly.
