Re-surfacing brake rotors

[Charlie Guthrie]

I have read the same expert opinions regarding cast iron not warping and the
pulsation being due solely to pad material being deposited unevenly. Let me
say this about that:
On the rotors that I have replaced due to pulsation, (that would be more
than 5 pair) (yes I'm a track junkie and I have way  more brake acceleration
than engine acceleration) I have routinely measured 0.005" to 0.008" of
runout near the outer surface of the rotor. Based on the rotor coloration,
there were uneven deposits of pad material, but not enough to account for
the variation in indicator runout. Also, I have had some of the rotors
turned with the minimum amount of material removed and usually they required
a second cut because the 0.003" initial cut did not clean up the entire
surface. Parts of the surface would show clean, cut metal while other parts
would still show the pad residue. This tells me that the variation in
indicator readings was not "entirely" due to the pad deposits being
uneven....
Nice theory, but it just doesn't hold up to my experience.
Now...do I believe that the warpage may be caused by uneven pad deposits?
Yeah, maybe. Carroll Shelby thought so as well as other "gurus." There are
also some folks that believe in Buffy the Vampire Slayer :-) Everyone
believes something...I believe I'll have another beer.
Charlie G