Driving 40 mph coming around a bend. There was a car stopped about to rear off to the left and when coming up around the turn I saw and tried to stop. I was about two car lengths behind the car when I pressed the brake down and I pushed it all the way down and nothing happened. It was grinding and shaky when pressing it down. Not tight or anything. I feel like I normally would have that tension right away to be able to stop. There was no warning or anything and the car always has warnings when something is close.