what? do you mean rotor?? no you probably aren't right, pick the car up and take a look, shake a few things around and see what moves.

 

I think you mean the dust shield thats behind the rotor. If they are bent they usually make a screeching when they rub up against the rotor. A rattle could be coming from many places.

 

like he said get the car up and get touchy feely

 

my dust shield is bent and its making noise too, so it can be that, like they said jack it up take your wheel off and look around.
does it make more noise when you turn your wheel????

 

bro a backing plate shield does not make a rattling noise unless it is complete rotted out falling apart from the knuckle... the sound it should be making is a rubbing noise continously but pitchy... If your more concerned about rattling... sounds to me like a exhaust heat shield... i could be wrong.. but like these guys said on top... jack your car and start moving things around...