. "When I hit the brakes, there is a very profound rumming noise, and the car does not stop the way it used to...it seems to slide...I tried bedding them, however, to no avail (actually I was told that these type of rotors do not need bedding...just drive normal !..???) I now have to hit the brakes HARD a few times, before it actually gets some sort of grip, and have to constantly hit the brakes mu" . . .