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After I put my summer rims on I noticed the rear rotors had a couple lines around them... almost look like something go wedged in between the pads and rotors like a stone or a piece of salt and then gouged a line around. I didn't think anything of it because aside from the lines, the pads were still making contact everywhere else (including right next to the line hence the clean surface) and the car still brakes and stops normally and very well actually with no noticeable change. Fast forward to now and both the rears seem to be scored pretty bad and now one of the fronts is JUST starting to go the same way. What the hell could be causing this?
I can't see it being a caliper or a slide because it is only a small maybe 5mm thick line or lines, whereas if a pad was not applying correctly it would make sense for a larger area of the rotor surface to be gouged, not just one line in the middle as the case is with the front one.
Just to clear up, the cleanest rotor is the front one that is just starting to do it. The worst one is the rear drivers side that originally had the marks in the spring. Then the other one is the other rear that has had a line for a little while and is now becoming worse.
What brand brake pads. I had problems with Raybestos Advanced Technology pads doing this. When I pulled it apart to check both times I had these problems there was a larger chunk of metal (or some other hard material) in the spot that was causing the groove. I contacted Raybestos and RockAuto. They sent new pads and I had the same problem with the next set. I went back to Delco and have never had it again. I have used Raybestos Advanced Technology pads on other cars of mine with great results. I don't know if it was a bad batch or what. Along with this groove, I got an intermittent screeching/grinding sound that irritated me immensely.
It might be worth inspecting the pads closely to see if you are having a similar problem.
I also had problems with 2 sets of Raybestos, although they were the pro series and they squealed like a dump truck.Regardless, I would grab a disc brake hardware kit from Carlson at Rockauto and guide pins if necessary. Lube them up good, makes a difference.
Don't let your local parts supplier talk you into any $1 packets of caliper lube near the register
either, get this as you will have it for sometime.
They're AC delco ceramics. They are Raybesto rotors though... I'll take them off and have a look. It sounds to me like the same problem Leadfoot described as a piece broken off.
07-26-2016, 11:37 AM
Rotor Scoring getting bad... 
