What causes a Shimano BR-505 front caliper to rattle? My lbs mechanic says the rattle is from a misaligned caliper. However the rattle does not sound like a rotor rubbing on a brake pad it sounds more like a tin can rattle filled with nuts and bolts. These Shimano brakes have a loose fitting cotter pin installed through the tops of the pads, which seems like it might be the culprit of this rattle--however why would this pin rattle on the front brake and generate no noise on the back brake. Could the rattle be from a loose or misaligned brake pad spring clip? Unfortunately, I do not own the bike so I can’t tear apart the brake or adjust it to figure out this problem. The Shimano brakes are on a 2011 Specialized RH Expert 29er that I was test riding. I do not have any experience with Shimano disc brakes. I do have lots of experience with Avid BB7s, J5s, J7's and Elixir 3s and have never heard any sound like this before.