A Clonk after stop and move again

toyota
highlander

#1

This the the right rear wheel. It is a 2001 highlander. I have all brakes replaced years ago at the dealer service center.

Then I heard the one clonk every time when the car start moving after a full stop. The first few stops in the morning are fine. Toyota said the calipers replacement needed. I have a Toyota certified mechanic replaced both and brakes (not genuine Toyota parts). He is not from the Toyota dealer. It was around 2009, June or July.

The noise seems not going away with the replacement. It was there but can’t tell when. The mechanic test drive and did not noticed that. It becomes almost every stop now. I took the car back to Toyota to check the front brake replacement this late July because I heard squeaking noise at braking two months ago. I had bought the life time replacement deal at the first brake replacement. Guess what, the dealer shop replaced my back brakes and told me my fronts are OK. I asked about the clonk I heard. Response was: it could be a lot of things. It could be the gas tank half filled. There is no uneven move at braking. I suspect it is a sticky caliper and that cause the replacement of the back brakes again. My son confirmed the noise location. Any suggestions what cause that? Thanks!