XPost: comp.mobile.android, misc.phone.mobile.iphone   
   From: me@privacy.invalid   
      
   "Vic Smith"  wrote in message   
   news:2b4m7hp2le1tl7anjbnleua0jiu1qsmfep@4ax.com...   
   > I agree that rotors don't warp "as in a potato chip."   
   > Rotors do warp "as in a warped rotor."   
      
   Is "warp" the right word to use for a rotor (disc) that remains as a flat   
   plane but with a surface that is not uniformly smooth over the whole area?   
   I'd always thought that a warped disc had a wavy surface like a potato chip   
   (aka potato crisp in the UK) or a vinyl LP - ie where the pads had to move   
   parallel to the rotor axis to remain in contact with the disc that was not a   
   perfectly flat plane.   
      
   Presumably if the surface becomes glazed in some parts and/or roughened in   
   some parts that causes different amounts of wear in the different areas,   
   exacerbating the problem.   
      
   What is the advice for avoiding rotor warping? How should one brake   
   differently to avoid it? I presume using engine braking (selecting a lower   
   gear) when going down a long hill reduces the amount and/or time that the   
   pads have to be in contact with the discs. I've also heard it said that if   
   you hold the car on the footbrake (rather than applying the handbrake or   
   transmission lock) after braking to a halt, the area of the disc that's in   
   contact with the hot disc will not be able to cool as much as the rest of   
   the disc, leading to "rotor warping" - which is another reason (in addition   
   to dazzling the person behind with your brake lights) for applying the   
   handbrake whenever you come to a stop. As my driving instructor drummed in   
   to me: "footbrake to stop the car; handbrake to *stay* stopped" - I can   
   still "hear" him saying that 40 years later ;-)   
      
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