Hi I have a friend who have a 83 380 SEL and have brake problems. He change the brake master cylinder, the pads are new, he also have new brake lines, but the car wont stop if you hit the brake pedal. also note that the booster if fine because the pedal feels fine. And if you hit the brake pedal hard only the front brake works and if he just brake normal the car wont stop. The pedal feels fine and do not go all the way to the floor.Thanks in advance