Originally posted by Chamuko
The spirals are not there for heat. When your pads touch the rotor they transform mechanical motion into heat. When this happens there is a huge ammount of friction and heat, enough to cause powder and gasses. The slots and dimples are there for theese gasses. If you want to get rid of heat , you would want more metal. the real and only "spirals" that matter are the internal ones. You ever look at your front rotors from the side? it has slots for the air to go through em and cool things down.

ditto. slots are there for better pad "bite" and to give powder/gases some place to go. the direction is irrelevant. the only reason rotors hafta be mounted a certain way is if the internal vanes are directional.