About 5-6 months ago I had brand new crossdrilled rotors and new pads put on all 4 corners of my GS400. This was done at the dealership that I worked at (Nissan) by a qualified mechanic (20 years exp. + a friend) Since this is not a big job to begin with and I had no problems until the last week or so I'm sure the install was done properly.
Last week I started to hear a continuous scrapping noise coming from the brakes (I think). This noise is constant, using or not using the brakes and will being making noise from take off until about 40kmph. After that I'm not sure if the noise stops or is just overcome with road noise. I travel the highways daily and there doesn't seem to be excessive heat buildup so it can't be that bad just rather noisy.
It sounds like something is dragging on the rotor.
Last night I got home and jacked up the front end and no noise.
Jacked up the rear end and the noise seems to be comming from the pass. side rear brake.
I no longer work for Nissan and I am now with Jaguar so simply running it through the shop is big $$$.
I will be putting on my summer rims and tire this weekend and will check out the noise while doing the rims.
What should I be looking for?
Axle boot look good no tears, etc.. really sounds like the brake.
Braking is perfect, just sounds like the pad is dragging?
Thoughts, ideas, images are all appreciated, thanks in advance.

 

Maybe the dust sheild has been hit and is just touching the rotor. A rock or something might have knocked it around.

 

I quickly checked that with the rear end jacked up without the tire removed. Looked ok will inspect further with wheel removed. Any other ideas if thats not the problem?
Is there something that could break off, snap or wedge with the rotor/pads?

 

Perhaps the brake spring clips (aka brake hardware) has worn allowing your pads to come into contact with the rotors.

IIRC the rear pads don't have wear indicators but I would pull all the pads to look for uneven wear ....

 

I think you need more anti-squeal compound....Im usually generous with that when I do my brakes.

Also check if there is any small pebbles stuck between the rotor and pad.