I took my rotors off to paint my calipers and didn't mark which side each one came off of. Which way do the curve on the slots go?
If I am standing on the passengers side looking at the car(the front of the car being to my right) would the slot go downward to the right or upward to the left? Basically would it be a frontslash or backslash?
Thanks to all on their help.

 

It's not the slot that matters; it's the curve of the vane inside the rotor. When viewing from the passenger side the inner vanes should go counterclockwise from the inner edge to the outer. The driver side will be the opposite.

 

The vanes inside the rotors are more important than the slots but many rotors have straight vanes and the rears are a strange bi-directional compromise (or at least I don't understand it).

In general you want the air to flow from the center out to the edge under forward rotation. You do not want to orient the vanes or slots to draw air towards the center.

ed

 

Thanks. My inner vanes are straight, and I put them on with the slot going counter clockwise, so I guess I am on the right track.

 

Wow, I didn't even think about the vanes when I got all my rotors turned a few weeks ago.

Thanks for the info!

james