The front brakes on 2013 Camry SE with 51,000 miles makes 1 to 2 clicking noise each time brake pedal is pressed...ONLY...when reversing. This noise does NOT occur when braking hard/soft going forward. However, this clicking noise occurs about 90%~100% of the time when braking during reverse driving. And it's not just first reverse braking that makes noise. If I hit the pedal 10 times while backing out of my long driveway, it will make click-click noise about 9 to 10 times. This clicking noise was always there from the beginning when I bought it new, but I've noticed that it's gotten little more louder over time. When I examine the pad, caliper, and rotor, all looks just fine, and the pad (amazingly) seem to have still more than 50% left. Perhaps because 80% is highway miles. Upon google-ing, I can see that many dozen users of this generation Camry are experiencing the same thing. From what I can read and from closely listening to the brake while my backed up the car dozens of times, it's definitely coming from the brake caliper area. It does sound like brake pad being shifted by the rotor when braking in reverse and I'm guessing that is causing the metal bracket to make clicking sound. Just to be clear, for each pedal press, it only clicks once or twice right at the beginning when you press the brake vs. clicking continuously the whole time you are pressing the brake pedal.

Update from Feb 5, 2017: Since the noise was getting slightly louder over time, today, I decided to make 100% certain that it was coming from the brake and not other areas like suspension. I took brake pads out, and applied caliper/brake grease to those normal (metal to metal) contact areas when you do the brake job, and sure enough, the 98% of the clicking noise has disappeared. The only slight click sound I hear when I pressed the brake pedal is the usual braking contact sound. For the newbies, make sure you don't apply grease to the brake pad or rotor. Only small thin layer of grease is applied to those metal brackets holding the pad, and back of the brake pad on the metal shim. Also I notice that brake pad has 9 to 10 mm padding left, and rotor was 28 to 29 mm. So, I have to be totally fair with Camry in that perhaps this wasn't a legit complain. The fact, original brake pads and rotors hardly wore off in 52K miles in 4 years, there was no need for any brake service, and hence the brake grease dried up and just needed some grease lubrication.