Rotor direction?

[Nine9six]

OK, I did something stoopid yesterday...I removed the front rotors to have them skim cut and am installing new pads. Upon removal, I did not mark the rotors (R / L). I know you can tell R from L by the p/n, but I still cant find a p/n on the damn things.

My rotors are OEM turbo's (cross drilled) from an 87 Turbo Look car, that have vanes running through the middle of the rotors. Kinda like an impeller on a pump. Common sense is telling me that when the rotor is installed correctly, the internal vanes as viewed from the OD edge of the rotors, should be in a "scooping" direction as the car rolls forward. This configuration would route air from the OD of the rotor and expell it through the ID (for cooling purposes). This is opposed to a "flinging" direction if installed in the opposite direction. Can anyone with a 87-89 turbo verify the direction of the rotor for me?
I hope my description makes sense...
Thank you...

[KTL]

Here you go. From the Porsche spec. book.



The venting of the rotor works in the opposite than you described. The cooling air is sent through the eye/center of the rotor and expelled out of the vents. The vents do not collect the cooling air and expel it thru the center.

[Nine9six]

Kevin,
Thank you so much!!! And here I was getting ready to reinstall incorrectly.
Thanks again from saving me from myself...

[MovOvr1]

I did the same thing the other day with my Maxima, but after seeing this thread I am now sure that I got them on right.

B

[Bill Verburg]

Not all rotors are directional, only those w/ curved vanes like the '78 up 930s.

Most especially the smaller ones have straight vanes which are non directional.

You can't look at the holes or slots either, you need to look at the vanes, as Kevin said the direction of air movement is center to edge.


The curved vanes are more efficient at speed, straight at lower speeds.