>The rule of thumb is as follows:  If when you drag your finger across the
>rotor or inner-drum surface and your fingernail catches in the
>grooves...you should check the specs to see if a grind would be feasible.
>I used to work for an auto-parts shop that routinely ground rotors that
>were obviously fine; yet another gimick for quick cash.  A little research
>and a micrometer can go a long way toward avoiding this pitfall...
>
>Seth B.
>'84 Westy
>
You all seem to be forgetting something...as the brake rotors wear, it's a
function of linear speed.  In other words, the outside edge of the rotor
turns faster than the inside edge (towards the hub).  Because of this, if
you mic the worn rotor, you'll find it thinner on the outside edge than
further in.  If you just throw new pads on an uncut rotor, the pads will not
be "square" to the rotor resulting in reduced braking (as least temporarily)
and possibly premature warpage (because rotor starts getting too thin before
next set of pads wear out).  I have experienced this on several occasions
and now refuse to put new pads on without at least checking the "runout".
JMO
Karl Batzler
84 Vanagon
192k