Hey Paul, couple of suggestions for you. when you remove these rotors look at the back side of the rotor, the hub has holes in it that alows rust to build up on the back side of the rotor between the lug holes, and if the rotor is not clocked the same when it is put back on, it will warp when it gets hot, also make sure the hub is clean of all rust before you install a new rotor or it will also warp from it not seating flat on the hub, and tighten the lugs evenly. Rich