I have a '99 Nissan Sentra 99,000 miles. I recently changed the brake pads and rotors (front) and there is a grinding sound coming from the left wheel when brakes are applied (audiable at low speed). And there is also a low scraping sound, when driving, from the right wheel (audiable at low speed). I took both wheels apart again and found no sign of rubbing from any other metals but one pad on the left wheel seems to be wearing unevenly. Maybe poor manufactufing. Can you explain to me the nature of the problem? Did I do something wrong? The brakes do work well.