[chopper]

Assuming that there are no malfunctions in the calipers (loose mounting bolts, etc.), I have a suggestion. The replacement pads which I used to get for my old Vette came with a small tube of red goop, which was spread in a thin layer on the rear side of the pad backing plate and allowed to dry before installing the pads. The material formed a semi-rigid film which then sat between the backing plate and the piston, and absorbed the small amplitude vibrations which cause the noise. If I'm not mistaken, this stuff is sold in most parts stores and speed shops.