Rotors are machined to have a slight wobble. This is to push the pads
back so they don't drag all the time when the hydraulic pressure is
released. There is no other method of retracting the pads on disk
brakes. Drum brakes have springs. Disk brakes don't.
The worst brake rotors that I've ever experienced, as far as "warping"
or hard spots is on the "modern" dogde. in 120k it is on the third set
of rotors, and it had pretty new rotors when we got it. At with that,
many miles were put on with brakes that shook from "warping" or hard
spots. These are ventilated.
I have NEVER had a problem with rotors "warping" or hard spots on an
MB. I think I have changed out either 3 or 5 in 40+ years and perhaps a
million miles in MBs. 2 of those were on the Hawaii Kai 200D whose
front rotors were way thinner than the minimum permitted when we got it,
and the odd one was from deep scoring due to a stuck rear caliper on the
240D.
Karl Wittnebel via Mercedes wrote on 12/29/18 1:31 PM:
Thanks Peter. Yes I am aware of the hard spot theory. It may even be true.
But when I put the new wheels on we had the car in the air and the rotor is
warped so badly on the left front that it binds on every revolution. So
anyone who says rotors don't warp and that the vibration is all from
cementite or whatever hard spots, doesn't really know what they are on
about. Or they never drove an older car.
I think the solid rotors warp far more than the vented ones. I imagine this
is just a stiffness thing related to thickness, but also to heat
dissipation and even the diameter. The rotor is too thin and the diameter
is too small for the car, basically. In pedestrian use it is fine, but when
you fail to notice the yellow until too late and go hard on the binders,
then end up in the crosswalk, there is no creeping forward, no creeping
backward. You can put the car in neutral or park and let off the brakes,
but the rotors are done after one rapid stop. Kind of silly. We are talking
a single aggressive stop from maybe 40 or 45 to zero, one time.
_______________________________________
http://www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/
To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
