Originally Posted by sfbimmer13
no not absolutely sure, however when they replaced them they said that the rotors where shot...how would I actually find out for sure if they are warped - I kept the old rotors?
They would need to be mounted and rotated while being measured with a sensitive probe for deflection/uneven surface. I don't know what the spec is for these rotors, but we are probably talking about in the region of 0.001".
The rotors can be glazed due to overheating of local areas, which changes the characteristic of the metal and causes uneven friction across the surface of the rotor, which results in vibration. The first time that happened to me, it went away after a few weeks of driving as I mentioned, but it might very well not, in which case you need to replace the rotor.