i have a 1964 biscayne, recently the brakes went out on me so i had to replace or rebuild just about the whole brake system, i replaced the master cylinder, rebuilt the wheel cylinders with new rubber stops and springs, replaced with new spring kits new drums and shoes, but yet i still have a problem with the brakes, the pedal still hits the floor, after all that ive still bled the lines on all four wheels to make sure there was no air in the line, but it does brake but not as well as i had it before, the lines seem fine. so my question is what could also be wrong with the car since it wont brake?