antonio

i have always machined my stock rotors when they needed it but i was wondering if you can machine (turn) cross-drilled rotors (c32 ones)? has anyone here machined theirs or can you not do it???? any help please.

Josh K

Someone correct me if I'm wrong, but I don't think Mercedes recommends turning rotors.

antonio

well, some don't recommend it because turned rotors get thinner and more susceptible to beibg warped. however, i don't think mercedes would discourage this otherwise there would be no need to have minimum limits printed on the rotors.

awiner

I've never heard of cross drilled rotors being able to be machined.

antonio

so you mean you have to buy new ones every other brake pad change (if you grind them)???? seems expensive. why is it that you can't machine them?

mbodo

I'm not so sure it's even physically possible to turn cross-drilled or slotted rotors, due to the fact that turning rotors in and of itself has the sole purpose of resurfacing or releveling the entire face of the disk. With holes/slots in the disk, I would imagine the machinery used to resurface the rotors would be damaged by coming into contact with the holes or slots.

Correct me if I'm wrong, but the machine that "turns" the rotors literally shaves off a 'slice' of the face, no?

Just my uneducated guess ...

antonio

yes, it resurfaces or shaves the face of the rotor. but what makes the turning any different than a non-cross drilled one? the surface is still smooth, regardless if it has holes in it or not, correct????

Steve Clark

Slotted/drilled rotors can be machined smooth again.However,the freshly turned rotors now have less mass and are less resistant to being overheated once again.I always replace brake pads early,and have never had to turn a rotor.Mercedes rotors are fairly inexpensive,so new ones aren't a lot more than having the old ones machined.
Front rotors for my C32 are about $90 a side,the 300TD's are each about half that.

Shine

Yes, I know ppl are rebuilding the rotors.the rotors look shining
after trimed.
I've also seen ppl have stock rotor drilled,get "Hi-end" appearance.

Consult authority to make sure the life time of trimmed rotor.

mmgrad

yeah, mb recommends changing your rotors each brake pad change because they want more money, and most people will believe what the advisors tell them... and, as my advisor tells me, they work on commission.. so the more they charge you, the more they make...

most people go by the rule of thumb that you should change your rotors approx every 2 pad change. if your rotors are still in excellent condition, maybe turning it once will be ok... as the saying goes, if it ain't broken, why fix it?

you won't get new tires if you didn't need it, right? rotors and pads are typical wear items... so when it looks worn out, replace it. if it looks usuable, but a little rough, then resurface it.