I just put 99+ gt front brake calipers on my 95 stang. The thing brakes fine when you are going forward but when you are backing the car up the thing starts to vibrate and surge when you apply the brake. Once or twice they have locked up and sometimes after you go from reverse to drive the caliper will still be rubbing on the rotor and I have to hit the brake real quick to release it and then everything is fine! Does anyone have a clue what this could be?