I bought a 1987 560 SL. The brakes vibrated a lot after a couple of weeks driving. I called the previous owner and he said the the rotors were just turned. I talked to the MB dealer and they told me to NOT turn rotors - only buy new. I bought new and the problem went away. My only experience with brakes. I now have a '97 SL with 72,000 miles and have not replace the brakes yet.
The dealer was telling the truth. MB rotors cannot be turned because they are CAST. If you use any other rotor, you can have them turned. Check carpartstogo.com for German Zimmermann cross-drilled rotors at the lowest price in the U.S. but when you tire of the black brake dust caused by the black graphite used in all German pads, try coximport .com for "Rotex" pads which use a very light gray compund and you'll hardly notice it. P.
Most brake rotors are cast. Non - cast rotors are seldom found in passenger cars. I believe that Zimmerman cross drilled rotors are actually cast too. By the way, drilling any rotor will damage the heat treatment of the material. Subsequent heat treatment may be possible but I believe cross drilling is a poor idea with modern pad materials. And cross drilling has never been shown to reduce brake rotor temperatures. Drilled rotors look nice and they have probably sold more Porsche's than any other "improvement". It's still a dumb idea.
The reason that turning Mercedes rotors is not recommended has more to do with the softness of their rotors. By the time the rotors are worn any significant amount, turning them will take them below minimum thickness and then you have to throw them out.
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