I had the same problem as CHARMZ too. It's not easy to see if the rubbing is on the inner part of the rotor. It was definitely easier to see when my car was racked and lifted.

 

Hello everyone, this is my first post. I was searching for a cause of an illusive noise on my GS rear brakes when turning to the right. This site looks very helpful so I thought I would post my findings. I could not detect by myself what side or wheel area the noise was coming from so I used my electronic ear microphones while driving. I determined it was the left rear and no matter how slight the turn to the right there was a harsh metal to metal scrape noise. At first I was looking for typical,backing plate rubbing after a normal brake job but I could not find anyplace it was making contact. I also checked and replaced the brake hardware. After looking at everything I could see I decided to inspect the old rotor that was removed during the job. When looking on the inside edge of the rotor there is a groove designed to match up with the parking brake backing plate. You cannot see this without the rotor removed. Turns out the old rotor has some fresh looking scars in this area. I pulled the new rotor and sure enough the lower area of this backing plate worn from rubbing metal to metal. My assumption is after my 296k miles my rear bearing has some slight play allowing contact under lateral force. My solution for today was to slightly grind this area of the backing plate (it's not a bendable area) to provide a bit more clearance. Problem solved. No more noise and just thought I would share.

 

I got my alignment done sort of did the job.... but my sound was more of a chuga chuga chuga chuga chuga (choo choo) sounds... okay jokes aside it sound like a train like motion....

 

I guess I should have recorded the sound for you but your description fits perfectly. This is a noise only produced during turns and very my an on off on off noise as it rubs one one section of the rotor. We are talking thousandths of an inch of machine tolerance that is starting the noise unless it's after a rotor replacement witch may increase the contact. If you could picture an old vinyl record and how they used to begin touching the needle as it was lowered. (If anyone remembers those) Mine was only contacting about half the rotor during the rub and missing the other part. If it were the face of a clock it was contacting say from 12 to 6 and missing the rest. Resulting in a scrape metal to metal noise.

 

Gridlock13 where in NY are you located I am in Brooklyn

 

hmm... I figured mostly it was my front left wheel making the sound cause it happens when turning but as you said play could happen in the rear.... All my rotors are rusted up and warped I'm going to change them on the weekend hopefully and see if i have the same exact problem... Tho I think my problem would be like some where its happening in the front

 

I'm getting this problem when turning left... It sounds like brake pads rubbing

 

My GS has the same noise when I turn, took my wheels off and checked my brake pads and well they were pretty much completely warn down. (I just purchased the car)

New pads are on the way.