One possibility: If this is first time removing the original rotors, you have to remove the "speed nuts" on the studs. These look like thin washers that are pressed on by Ford during manufacturing to hold the rotors on B4 the rest of the brake components are attached. About the size of a quarter, usually on 2 or 3 of the studs. You'll have to put a screwdriver or some other wedging tool between them and the rotors, and then twist, pry and pull them off. They do not need to be put back on. I am presuming you are refering to your front brakes.
