> >I've also heard a theory that it's caused by sitting with your foot on
> the brake after heavy braking.  (The theory being that the rotor cools
> differently where it's clamped by the caliper.)  Personally, the only
> warped rotor I've had was done in by a draggy caliper, so heating was
> definately the culprit there.
>
> This can definitely warp the discs, keeping foot on brake after a high
speed
> braking session, or multiples thereof, don't forget they're glowing red
> after a a few fast roundabouts (90 - 40), 90 - 40 and then 90>0 in a 1 ton
> vehicle (and if you have roundabouts there.)

I'd add to this that although I doubt overtightening the wheel nuts (lugs, I
ask you!) causes disc warping on most hub designs, its remotely possible
that a corroded/dirty hub face contact might. Touch the wheel after a lot of
hard braking - a very large heat sink like that milling in the wind and it
can still get pretty hot, especially with binding brakes. Cleaning the back
face of the wheel and hub mating face would avert this (slight) risk.
Much more likely is the one above (holding foot on brake after stopping) and
also of course binding brakes. Automatics would also be more prone, as the
brakes are required a lot more - but I wouldn't touch one with barge-pole -
so I'm alright Jack.

Clive Smith
'88 Syncro Transporter