Hey guys so recently my 03 350z has been making a super loud scrapping noise like nails on a chaulkboard (Very loud). I took a look and noticed that there is a white ring scrapped on my left rear rotor. The noise happens when I accelerate hard and sometimes when backing out of a inclined driveway while turning. Suprisinly the noise does not happen when braking. I checked my pads thinking it could be a wear indicator but there is none on the pads. The most recent thing I did to the car was the Spring Mount mod.
Any ideas?

 

A rock/pebble stuck between your rotor and brake pad? .. Have you pop the caliper to see if anything is wrong?

 

white sounds like a
pebble..

 

Already took the break pad out to look at it didn't see any rocks. What I think it could be is the metal shims that the break pad goes into. Could it possibly be that I didn't get an alignment after the spring perch mod ? Or could have something not have been tightened up? Also on the highway I noticed when accelerating hard the car feels like it is on ice as in the rear end feels like it is fishtailing.

 

Took a deeper look today, found out that my Axel nut was basically off. I was able to unscrew the axel nut with my hands (Very Scary). Tightened up the nut and everything seems alright now.

 

Shouldn't there be a cotter pin there to keep it from loosening?

 

Cotterpin for some reason is about an inch away from where the nut can be tightend to.