Rotor Direction - 2008 e90 m3

[fillytown]

Hey Guys,

Ive tried searching for the answer but haven't found the answer.

I am replacing my brake pads, and while doing so my friend told me that my rotors are backwards. The rotors were last put on at the dealership, but I wanted to post the picture and perhaps someone can clarify.

The attached picture is of my rear left (driver side rear) rotor on my e90 m3 2008.

Thanks guys!

[Rat3d ///M]

they are correct

[Amirsm3]

Your friend is mistaken lol.

[roastbeef]

Correct. They wave the air out, not cut it in.

[Richbot]

Your friend's wrong.

However, the BMW rotors are backwards from some aftermarket rotors in that the holes are "swept back" from the direction of rotation My ECS rotor holes sweep toward the direction of travel, opposite the direction of the vanes, and same deal with my slotted front stoptech rotors

OEM:


ECS:

[fillytown]

Awesome, thanks guys! Much appreciated.

[dparm]

The holes themselves are not a good indicator of anything. It's the direction of the internal vanes that matters.

[roastbeef]

There was a thread on here a while back where someone did a bbk install with two of the same side rear rotors. One rotor was "cutting" and one was "wafting."
I'm no expert but in the long run, if one rotor was hotter than the other it may have a negative impact in balance at the track.

[Amirsm3]

Originally Posted by roastbeef

There was a thread on here a while back where someone did a bbk install with two of the same side rear rotors. One rotor was "cutting" and one was "wafting."
I'm no expert but in the long run, if one rotor was hotter than the other it may have a negative impact in balance at the track.

No need to be an expert, that's just common sense, lol.

[InnerBlueSkies]

Sorry for the old bump but I just spent an hour trying to determine whether I installed my rotors correctly. The sound answer cannot be determined solely by the layout of the holes but rather the flow of the veins as one poster suggested.

For a non car DIYer such as myself, one would be led to to believe you want to draw cold air into the disc, quite the opposite. *** I got lucky here just following a low left-high right drill pattern.

https://www.cquence.net/blog/how_to_..._brake_rotors/

[Denny347]

Originally Posted by InnerBlueSkies

Sorry for the old bump but I just spent an hour trying to determine whether I installed my rotors correctly. The sound answer cannot be determined solely by the layout of the holes but rather the flow of the veins as one poster suggested.

For a non car DIYer such as myself, one would be led to to believe you want to draw cold air into the disc, quite the opposite. *** I got lucky here just following a low left-high right drill pattern.

https://www.cquence.net/blog/how_to_..._brake_rotors/

That is really good information. I just assumed that the direction of the holes indicated the direction of the veins. I learned something new.