Originally Posted by oldbobcat

Riders will continually knock the caliper to one side when they replace the wheel, and then recenter it using the screw. Some mechanics will do this too, I've noticed. After a few of these adjustments, one pad will be too high and the other too low, and the screw will bottom out or fall out. It's best to center the caliper like Kontact said, and then use the screw for fine adjustment, like after a few hundred miles of pad wear.