The other day I droped my tranny pan and changed the filter hopeing this would solve a shifting problem I have. When I put everything back together and started to drive I hit the brakes and they went stright to the floor and nothing happend. I started rolling backward(was going up a hill) and couldn't stop. It has plenty of fluid. I was wondering what the hell the problem could be?

 

master cylinder is the first thing that comes to mind also check your booster but i would put money on the master cylinder if the booster goes out like in my buddies full size the pedal got rock hard replaced that just to end up replacing the master cylinder as well so change the master cylinder first bleed out your system accordingly then see what happens

 

Yup, master cylinder. If the fluid is ok and there are no leaks and the brake pedal goes to the floor, it's a faulty master cylinder.