Bryan
The shiny spots are hard spots in the cast iron caused by overheating and
cooling cycles. Cummins cylinder liners used to do the same thing if you
really overheated them.
I think the pulsations are caused by uneven rotor thickness or warpage. If
the rotors have enough metal I would have had them turned and new pads.
After all the cycles they will have taken a set and probably won't warp
again. Trouble is, today they are so close to the minimum thickness when
new to save weight and gain mileage.
Years ago I remember reading that Grumpy Jenkins used nothing but used
blocks because they had taken a set and wouldn't shift.
JMHO
Ron Gibson, Omaha NE
> 42,000 miles on the van.
> Noise and pedal pulsation (fast) starting 3-5 seconds into hard , high
> speed breaking. Example, 5% down grade at 75 MPH and break hard to
> drop speed to 40 MPH. It's not ABS. ABS does not pulse that fast.
>
> All four surfaces on the rotors look similar. The spots are very shiny.
>
> Any information, opinion, suggestion or wild ass guesses will be
> appreciated.
>
> Thank you,
> Bryan (I installed new raybestos rotors & pads)
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