This may be obvious, but I ordered a set of front and rear rotors from R1 concepts; how do I tell which are the front and which are the back? I know which rotors are pairs (because of the part numbers) but I don't know how to determine the front from the back.

Also, What direction should the rotors be pointed on the car?

Like this: http://www.bmw-sg.com/features/leube...-uber-z4-4.JPG (what I would consider backwards)

Or the opposite way?

The rears have a larger hat and its more offset to accommodate the parking brake shoes.

For direction, they should be oriented so that the vanes bite into the air as they spin when the car is traveling forward. If the vanes aren't directional, however you want.

Also, the rear rotors are solid, at least most are. And the fronts have an air gap between the two braking sides.

How do I know tell which way the vanes are pointed?

This...........

The Driver's FRONT side disc.



Here is a picture of the front disc.



And here is the picture of the rear disc. You can tell the difference in the size of the hat as compared to the front.

Thanks Geddy

My factory rears are vented... Curious.

As for direction, here's a link to explain how they should be oriented:
http://www.centricparts.com/98-000-0...tion-email.pdf