Probably this question has been discussed many times, but this is my first post to the group, and there was an active discussion at the 2005 Consorso Italiano BMW Corral this past weekend about the correct direction that the E34 M5 throwing stars should point.

I have knowledge from my body shop expert in the San Jose area that BMW labels their asymmetric part numbers with, I think, an odd part number for the left side of the car, and an even part number for the right side of the car. Since the throwing stars are asymmetric, i.e. the left and right are different, the part numbering scheme falls under this definition.

Whatever the part number/side of car part number direction, it boils down to the correct part numbers for the left/right side of the car. Using this part numbering scheme, the correct direction, according to my body shop expert, for the throwing stars is to have the blunt edge facing the direction of rotation. This is opposite from the direction that intuitively appears from looking at the throwing star covers. Anyway, with the covers in the direction I described, the car looks like it is moving even at rest, which adds to the looks of the car. And aerodynamics for brake cooling kind of make sense that the blunt edge should face the direction of rotation, if it is thought about enough. The blunt edge will create a high pressure area. If the streamlined edge is facing the direction of rotation, it would create a low pressure area near the brakes, directing external airflow away from the brakes, not toward them. But, I am not an aerodynamic engineer, and I have not been able to find photos of the original setup. Any aerospace engineers out there that could explain this???

The funny thing is that in pictures in magazines and on the web, I have seen both directions shown. You probably have, also. I have even seen cars in magazines that have different directions for the front and rear wheels, which makes no sense whatsoever.

So I am willing to undergo any flaming and discussion about this subject, just to try to get at a consensus about this....

Jeff Cooper
San Jose, CA