[Biturbos4] HID light cutoff

[Quincy Chiang]

Hi all,

I have European-spec HID headlights (ecodes) in my S4, and I gotta say the difference is very noticeable.  See the picture in the link below, left is my S4 with ecodes, right is my ex-A4 with North American-spec HID headlights:

http://pictureposter.audiworld.com/41218/ecode_vs_us-spec_beam_pattern.jpg

My Canadian S4 doesn't come with stock HID (stupid crash standards...), so the ballasts and bulbs are Phillips aftermarket, but it is 4100 or 4300K, same as stock.  As you can see, the ecodes' cut-off is even sharper, and it has a higher tilt to the right to illuminate road signs better.  They also concentrate more light to the center, right where you want to, but I think this is because of the smooth projector lens in the ecodes, as NA-spec projector lens have concentric rings in it.

John, if you modify the cutoff, you may as well just aim the low beams higher.  I believe the sharp cutoff is required to minimize glare to oncoming traffic, so I don't recommend doing anything to them.  I'd re-aim them a little higher, as the headlights are often aimed too low when they leave the factory.  Other than the, your auto-leveling is supposed to help a bit it the situations you describe, but I've found them largely useless.  I don't miss that feature at all in my S4.

HTH.

Quincy
'01.5 S4 - best possible lighting $$ can buy for my car
'09 CoupeQ - worse lighting ever, thanks for nothing DOT!


----- Original Message -----
From: John <AudiFans at BackYardEngineering.com>
Date: Thursday, January 19, 2006 2:56 pm
Subject: Re: [Biturbos4] HID light cutoff

> Mark Quinn wrote:
> > I love the HID lights on my A6 but hate the sharp cutoff, especially
> > when going downhill or down dips when you can't see 5 ft in 
> front of the
> > car!
> > 
> > I know this cutoff is formed by a motorized (for adjustment) 
> plate. 
> > What I want to know is if it might be possibly to cut slots or a 
> zig-zag
> > line in the plate to give a softer rolloff (rather than a 
> cutoff)?  Has
> > anyone tried this.  Or can anyone who may have taken their 
> lights apart,
> > comment on the feasability of this?
> > 
> > Or am I just blowing smoke?
> > 
> > -Mark Quinn
> > 2001 A6 2.7t (various mods)
> 
> You're just blowing smoke...  ;-)  The Audi HID lights of some of 
> the best DOT
> lights I've seen. That said, they are still slightly different in 
> beam pattern
> to the ECE versions. The sharp cut off is what allows more light 
> on the road
> instead of the oncoming drivers face. It also make them good in 
> the fog. There
> is an auto-leveling mechanism, but that has nothing to do with 
> beam pattern. I
> get the impression that the DOT version is stingier on the upsweep 
> to the right
> and that most factories and dealers tend to be real conservative 
> adjusting US
> headlights. You could relatively easily and cheaply replace the 
> HID lamp only
> with the ECE version. Might not make a noticeable difference to 
> you... We have
> the same car you do and it was delivered with the low beam low 
> enough to leave a
> large dark gap between the low pattern and the high beam pattern. 
> :-/ I
> readjusted them and they're better, but IMHO still weak on the 
> right upsweep.
> The adjustment for the HID requires VAG-COM or equivalent... If 
> you're going to
> do it yourself, keep in mind a correct low beam adjustment is 
> angled down and
> still has the sharp cutoff touching the ground...  When you're 
> playing with
> VAG-COM, be sure and note the current settings before changing 
> anything.<" 
> target="l">http://forums.audiworld.com/a4gen2/msgs/205827.phtml>
> John
> 
> 
> 
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