Inspect the pads for uneven wear, and if both are the same compare to the other side wheel.  Every time I've had  a stuck caliper one pad has been near zero and the other fine.  Do you have a parking brake cable on this set up?  That can do it too if it's too tight or that side is frozen with rust.

Stuart
 
My right rear wheel shows 10 times the brake dust of my left rear wheel [gowesty wheels, Audi 500 turbo rears disk conversion]. Could this be a sign of a hanging caliper? 

Mike in Cotati, no matter what BenT says.