So somebody posted about a banging noise when backing up and i was having the same problem. what i found out was when i replaced my brakes i removed a lil metal piece that seemed useless and now i realized that the metal piece was actually a brace of some sort for the brake pads, now that is gone pads slide around a lil bit maybe les than a 1/4 inch and create a banging noise when braking. You'll get the same noise if your discs are not completely flat.

So i'll have to look at some junkyards to see if i can get those metal pieces back.

It doesn't seem to be too much of a big deal but due to the fact i have had no problems with my brakes except for that strange noise.

 

yeah i got that noise, i'm hoping it will be gone when i replace my pads and rotors.