///M Rotors

[4.6is Ryder]

Maybe I missed something, but has anyone figured out why the X5 and X6///M don't have cross drilled rotors like all the other ///M's? Hell you can even order them on a 1 series as a brake upgrade......Phil

[FSETH]

There is no reason for cross drilled. If they were drilled, they would need to be larger to have the same metal mass as plain rotors for heat dissipation. They are probably as big as they can be already and still fit behind the wheel. Cross drilled does not mean shorter stopping distances.

[4.6is Ryder]

Originally Posted by FSETH

There is no reason for cross drilled. If they were drilled, they would need to be larger to have the same metal mass as plain rotors for heat dissipation. They are probably as big as they can be already and still fit behind the wheel. Cross drilled does not mean shorter stopping distances.

Agreed but you would think BMW would use the same thought process on the X's that they use on other ///M's. I was thinking that the additional weight might have played a role in the decision. I think the cross drilled rotors would add another piece to the aggressive look........Phil

[JCL]

Originally Posted by 4.6is Ryder

Agreed but you would think BMW would use the same thought process on the X's that they use on other ///M's.

But they didn't use the same thought process. They changed to AWD, turbochargers, automatic transmissions, and so on. The X5M is an incredible piece of engineering, but it goes off on a real tangent for the M division, breaking many of the previous rules.

As to the non-drilled rotors, it may be to improve thermal performance since this is the heaviest high performance vehicle BMW has built, and those brakes are going to get very hot.