brakes

[gismo0184]

are slotted better than cross drilled??

[Grant@Tirerack]

The only time cross drilled rotors make sense from a mechanical standpoint is when the size or mass of the rotor is increased to make up for the material they are removing when they drill out the holes. Rotors function by acting as a heat sink. The movement of the car is converted into heat energy by the pad and rotor rubbing together. The rotor absorbs that heat and dissipates it. The more mass you remove from the rotor, the less effective it will be in absorbing that heat. That required mass is designed into the rotor based on the vehicle weight. If you take a stock size/weight rotor and drill holes in it, you remove some of it's mass and make it less efficent. You may get some better wet braking and venting of pad gas but you loose more in hard braking and higher temperature braking situations. If this is on a race car where they replace the rotors after each race event, it's a fairly good trade-off. For daily driving, that excessive heat buildup will lead to warping and cracking in the rotors. Slotted rotors offer all of the benefits of better wet braking and pad degassing while removing far less material/mass from the rotor. Slotted are the way to go.

[alfonso2501]

Hi Grant, you mentioned that slotted rotors improve breaking in the wet. I’ve never heard of this before. Could you please explain? Thanks.