Friday I had Hawk HPS pads and new brembo rotors put on the front of my car. Over the weekend, the left brake started thumping rhythmically upon braking, and I could also feel it in my pedal. By monday, this had turned into a metal on metal sound, a clanging. I returned to my garage and I discovered that the bracket holding the caliper had a stripped bolt. I replaced the caliper with a rebuilt one and now the thumping has started again. Any ideas as to what is going on? This is at low speeds, high speeds, etc.