Which way do the grooves go? - Page 2 - The Unofficial BMW M5 Messageboard (m5board.com)

KBK · 10th June 2006, 05:52

Must be a reason. It could be as simple as it has been shown, that over time, they are less likely to develop a crack. Who knows. Or, that overall..there is no remotely measurable performance difference, so the manufacturers do what they like. Could even be a pad dislocation (walking) issue.

jaj · 10th June 2006, 08:11

The rotors go on with the vanes inside producing a pumping action that throws air "out" of the rotor as it turns. Putting them on the wrong way hinders the cooling process considerably and may cause pad fade (read: not good).

The slots end up whichever way around that the manufacturer decided that they should end up - it's the internal fins that matter.

I suppose the "forward slanting" fins pulls the pads into the center of the rotor, but the effect will be minimal.

Cheers
JJ

E55AMG2 · 10th June 2006, 16:17

Actually, they mount them that way on track cars to help keep the pads clean and to aid the radial vents in pulling air thru the rotor to keep it cool. The venting effect (for pad outgassing) works regardless of the direction of the slots.