Brake Calipers...
 

About 3 weeks ago, something in the back of my car started making a thunk sound, as if a bowling ball were rolling around in my trunk and hitting the sides. It only happened when I took my foot off the gas pedal, didn't matter if I eased it off or jerked it off, it thunked. Really loud on first-third gears, less of a thunk fourth-sixth. Freaked me out, rushed it to the dealership - they drove it around and heard the noise, tore the rear axle and other assorted items apart, tightened everything they could up, and pronounced the whole mess fine. Shenanigans!! As soon as I pulled out... thunk. Went through this rigamarole several times - they finally slapped a microphone underneath the car, drove it around, and isolated it to a brake caliper... replaced it and she's back to normal.

Has this happened to anyone else?? Has this been addressed by Mazda in the past or is this just a freak occurance?

the actual caliper? what was it doing? are you using the same pad that was on the old caliper?