Originally posted by: Zenmervolt
Originally posted by: 91TTZ
Originally posted by: Apex
Originally posted by: Zenmervolt
Originally posted by: Apex
HID bulbs may or may not change the cutoff. This is because the arc from the HID is bright at a slightly different place than the filament on the halogen bulb. Will it make the cutoff less sharp for sure? There's no way to tell until you test it. However, there's a pretty good chance it will. Definitely not 100% chance, like some would like to imply though.
Changing the shape and positioning
WILL change the beam pattern. Period. The laws of optics do not bend because we want them to. Just because the cutoff looks clear does not mean that the beam pattern is acceptable. The cutoff is a very small part of the overall beam pattern.
There
is a
100% chance that using a HID bulb in a housing designed for halogen filament bulbs will alter the beam pattern. There are no ifs, ands, or buts about it.
ZV
I never said the beam pattern will not change, only the cutoff. Will the beam pattern get worse? Probably, but not necessarily. One assumes too much if he assumes the original beam pattern is the best. Often, the original beam pattern is already pretty compromised.
The fact remains that the only way to see if there is an improvement or reduction in usability and glare is to try it. Period.
I agree that you'll never know until you try it. Obviously if two bulbs place the filament/arc in different positions, it will change the beam characteristics. However, the plug-in HID kits do their best to place the arc in the same spot as the filament on the old bulb. It may not be exactly 100%, but most cars on the road aren't properly aimed anyway.
I can tell you from my own experience that the HID bulbs produced a beam pattern that was damn close to my old halogens, to the point of not even needing to be re-aimed. The beam pattern on my car most definitely did not experience this horrible degradation that some claimed it would.
The shape of the light source is very different. Even if it's in the same place (which it isn't, and no matter how close they get, it's still not right) the differing shapes will cause issues.
And the simple fact is that it remains illegal to put any headlight bulb into a socket not designed for it if you are going to drive the vehicle on public roads.
My position is always to do it right or not to bother. Doing it right in this case means replacing the entire assembly, including the reflector and lens.
For more detailed information, one can go here:
http://www.danielsternlighting...sions/conversions.html
I seriously doubt that if your HID lights were evaluated scientifically they would still be producing a legal beam pattern, regardless of the perceived improvement.
ZV