Does it matter which way whether drilled, slotted or both...In my case I have slotted and my rotors where put on in by myself in a way where the slots go the same direction as the rotation of the wheel...But does it matter which way the slots go? Also, does braking power increase or decrease in any of these meathods...AND IS THIS A DUMB QUESTION...

 

Direction on the slots is a tough question. I think about the only thing it'd effect would be pad wear.

Braking power is pretty unneffected by slotting or cross-drilling. The original concept of the slots or holes was to allow brake gasses to escape from being trapped between the pad and the rotor. Since modern pads don't let off these gasses, they become unnecessary. The slots will help keep the pad smoother but will also wear the pad faster. Cross-drilled rotors are at higher risk of fracture due to being perforated.

 

I have seen the slots going both direction on different cars from the factory. What actually matters more I think is which way the vains inside the rotor rotate. If the vains are directional (and some are) then you want the vains rotating in a way to scoop the air into the rotor. I hope that makes sense.

 

Hmm... and I thought it made more sense that the veins be oriented so that hot gases/air escaped out of the vein due to centripetal forces.

 

drilled disk cracks very easily, esp. with non-casted disk

 

That's what I would have thought too! The idea being that air is drawn through the system to help keep things cooled off. Angleing the vains such that they push air toward the center of the hub would be working against the natural centripetal forces that Tabach0y273 mentions. It seems to me that that would be counter productive.

Just a thought!
Drive Safe,
Steve R.