Originally Posted by greasegunn
Originally Posted by domer10
I would say warped rotor, this is why I do not cheap out with rotors anymore. I know you said you did not, but from experience this sounds like a warped rotor. The junk metal is proliferating into the mid level options for parts with certain manufacturers unfortunately.
I used top end Raybestos rotors. The thing I can't get my head around is the inconsistency - if the rotor is warped or if there is lateral runout wouldn't it be consistent and not vary?
There is extensive discussion of failure modes leading to shudder here on BITOG, already.
Rotor thickness- rare, but easily checked. Use a micrometer at 8 points around the rotor, any differences should be less than a .001" micrometer can measure.
Rotor was already warped when new - rare, but it happens. Check on vehicle with a dial indicator.
Rotor wears unevenly in thickness - usually only seen on hard use service vehicles with semi-metallic pads. Check with both micrometer and dial indicator.
Rotor warps in use - most common diagnosis, but not nearly as common as commonly thought. In 100% of the many diagnosis I have seen personally, the shop had zero physical evidence (did not use measuring instruments). I have proven a few wrong, and found one of the next two to be the cause.
Rotor was installed a crooked - very common. Check on vehicle with a dial indicator. A rotor installed crooked may not be salvageable. At a minimum the pad buildup needs to be removed.
Rotor has pad imprinting, uneven pad desposits - very common. Especially now with the ongoing elimination of copper in pads, which helped scrape the rotors clean.