dandingo

Quick question:

Are the holes in cross-drilled rotors directional?

I just installed a pair and noticed that the holes were in the same pattern on both rotors (so one side of the car has the holes in the opposite direction). I didn't pay any mind at the time, but now that I think about it... seems a bit odd.

Thanks.

-Dan

Josh K

I wouldn't worry about that. Cars with the x-drilled rotors as OE from Mercedes have the same thing.

dandingo

Thanks!

bbearden

I know the holes really don't matter but I have heard that slotted rotors are directional. A friend of mine installed drilled and slotted rotors in the wrong direction (left on right and vice versa) but it has yet to create any uneven wear patterns on the pads or rotors. I do know that if you are searching for upgraded rotors and opt for the x-drilled ones, ensure the holes are chamfered to relieve stresses during machining or you can have problems with cracking in the future.

lowphat

I have drilled and slotted Brembos. The holes might not make a difference but I beleive the slots do. Both holes and slots are directional on my setup. They are installed so that if you were loking at the particular wheel from the side of the car, at the top of each rotor the angle of the slot and the hole pattern starts at the outside of the rotor and angles down towards the inside of the rotor. At the top of the rotor, the top of the slot is ahead of the bottom of the slot as the wheel rotates. I beleive that it matters in terms of the slots because besides the function of clearing the pads as they pass over the slot, the slots also help to vent gasses created during the braking process. Angling the slots as described above would cause the gasses to vent out from the center of the wheel rather then back in towards the center. A more efficient process.

theine

My front rotors (C32 AMG) both are left, I think this is standard with mercedes, my rear Brembo's both rotate against the tire movement.