Coupe Quattro rotor warpage -Reply

[Gross Scruggs <GScruggs@wposmtp.nps.navy.mil>]

I read an article several years ago about the research that Cadillac did trying
to find out why rotors warp.  The real puzzle was why don't ALL warp.  What they
found was that the problem is directly related to the meatallurgical purity of
the rotors.  The more homogenous the metal in the rotor the less the likely it
will warp.  The mechanism involved is that  where 'different' metals trapped in
the same shape and are subjected to repetitive hot/cold cycles.  The shape of
the object changes.  When you intentionally make an object do this it is called
a 'bimetallic strip'.  When you don't want this to happen it is called a warped
rotor.

What does this mean for us as consumers?  It means we are screwed and can do
very little about it.  When we go down to the parts store and buy replacement
rotors we are at the mercy of the fates.  I have no experience here but I
suspect that when we buy expensive aftermarket rotors we are getting a more
homogenous casting/forging which will have less warpage.  I suspect that being
drilled or slotted or vented has little or nothing to do with the causes of
warping.

So, when your rotors warp don't feel guilty that you've been abusing them or
you've got the wrong pads or such.  They probably would have warped on your
grandmother's trip to the shuffleboard tournament.

Regards,  Gross 
'87 5kTQ
"My Karma ran over my Dogma"