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Originally Posted by VTECaddict
If you want to adjust to US DOT headlight aiming regulations, The left half of the beam should drop 2" below the center of the headlight projector/reflector at 25' in front of the car. The left half of the left and right beams should be level with each other.
http://www.danielsternlighting.com/tech/aim/aim.html |
I have great respect for Daniel Stern and the amount of good information and resources his site provides.
However, for anyone wanting to vertically aim the Reflector Based LED Headlamps on their BMW properly and have NOT made any coding changes, the defined slope, plus the beam reference point height is used to determine the height at the reference distance. The Reflector LED's use a Harmonized E4 ECE/DOT Beam Pattern. VOL recommendations like those you linked can be used safely, but they are not optimal due to the light distribution differences.
Every BMW will have a permanent marking of the Percentage Slope Down on the headlamps (*Image 2* - some may even have two different gradients that will be notated as SAE -x% and ECE -x%; if they are not coded in any way, SAE value should be used).
Using the DOT Alignment point (it will be on the outer lens, approximately in the middle of the outer chamber horizontally and approx level with the top of the upper reflector vertically. It's a tiny circle with crosshairs that can be difficult to see (Image 3). The height of that point sets the Rise Value for the height at the beginning of the run using the slope value of the headlamp.