[s-cars] apparently warped rotors, when hot

[Steve Marinello]

A question to the list...

Does it make sense for front rotors to act warped after they heat up, but
not until then?

The sedan I purchased a while ago had nearly new drilled Zimmermann rotors
on the G60's up front.  Having had to replace the pads (Red Box installed)
I went to bedding them in.  Some 10-15 second  drag breaking to heat them up
some and then started the bedding in with the stepped up speed and breaking
episodes.  Nice, smooth breaking for the first set, then after a bit started
a second set.  Third one in from about 60 mph, the steering wheel starts
dancing in my hands.  WTF?!  Tried it again; same thing.  Drove a bit and
did it again...smooth.  And so it goes.  Sometimes smooth; sometimes feeling
warped, but almost always when they've been nominally heated up.  Not hot,
buy any means.

In any case, slapped a set of used stock rotors on it and the problem
doesn't seem to exist.  Longer pedal travel 'cause they're worn, but no
shimmy.

Any similar experiences?  If it seems to do it only when it's warmed up,
does it make any sense to turn the rotors?  They don't seem to show a warp,
at least when cold.  They're barely worn; not much more than a fingernail
thickness lip.

TIA,

Steve