[s-cars] hid 'upgrades'

Tue Jul 9 20:10:47 EDT 2002

Chris:

Agree with what you've said regarding most HID kits, and I don't think your
post was intended as a direct response to my conversion.

Still, I wanted to clarify that the entire reflector module (including
convex refectory lens, reflector, bulb and ballast) from the new A6 xenon
was grafted into the Ur housing by means of an adapter bracket in the
conversion that both Igor and I completed.  Since the entire "bullet" is
replaced as a unit, the beam pattern is new A6.   What is lost versus OEM,
and is annoying to other drivers, is the auto dimming feature, so if my car
is loaded down or I am on an incline, I get some protests from drivers in
the oncoming lane. I have the auto dimming stepper motors from the new A6
housings, and can confirm that they will fit without modification into the
Ur housing, but I haven't tried to figure out the circuit to needed to
operate them and to keep them in synch with each other. Too many little blue
wires and too little time for me to bother.

This is a fairly inexpensive way to have outstanding lighting, and keep
factory part numbers throughout.  It addresses and corrects most of the
shortcomings of the aftermarket kits.

Bob

-----Original Message-----
From: Chris Covington [mailto:malth at umich.edu]
Sent: Tuesday, July 09, 2002 6:28 PM
To: Kenneth Chang
Cc: s-car-list at audifans.com
Subject: [s-cars] hid 'upgrades'

People have 'upgraded' their UrSs to Xenon, however that is not the proper
light source originally engineered for the headlights and it does not
produce the correct output, even if it does 'seem' brighter to others -
it's also probably very disturbing.

The only proper, legitimate way to do this is to get the factory Euro C4
HID headlight system and install it.

Here's why:

(Read from:

http://lighting.mbz.org/tech/info/bulbs/HID/conversion/)

"Trying to "convert" halogen headlamps to HID is an unsafe thing to do.
There are *NO* legitimate or safe HID retrofits for the headlamps of any
car which didn't have HID lamps as a factory option. Here's why:
HID (High Intensity Discharge) headlamps use an arc capsule where an arc
jumps between two electrodes. This arc is used as the light source,
instead of a glowing filament. Not only is it very important to have the
light source (filament or arc) at exactly the right spot in the reflector
for the lamp to produce a proper beam, but the source (filament or arc)
must also be oriented correctly--either fore-and-aft, or side-to-side,
depending on the design of the lamp. In addition, headlamps that produce
both a high and a low beam must have a bulb with not one, but TWO
filaments, each of which must be very precisely located and, in the case
of some low beam filaments, shielded. In this game, fractions of a
millimeter count! The only way to assure the correct placement of the
source in the lamp is to use the correct bulb type. Most people don't
realize this, however, and there are some unscrupulous types, placing
their wallets before your safety, who make a buck off of your NOT knowing
how crucial it is to use the correct source in your headlamp.

These "conversions" generally consist of a headlamp bulb base that has
been drilled-out, with an HID arc capsule crammed in and glued. Sometimes
instead, there's a semipermanent adaptor plate that fits where the bulb
would go, with the HID arc capsule fitting inside of the plate.

There are no HID arc capsules that have more than one arc (i.e. high beam
and low beam in one capsule, as found in 9004, 9007, H4, HB2, and most all
sealed-beam headlamps.

There are no HID arc capsules that have a transverse (side-to-side) arc
path. 9004 headlamps and most all sealed beams use transverse filaments.

Even if we consider replacing a single-axial-filament bulb with a
single-axial-arc capsule, these so-called conversions are unsafe. The
quantity and nature of the light put out by the arc is quite different
from that of the filament, and the reflector and optics of a halogen
headlamp are not designed to produce a proper headlamp beam with anything
but a halogen bulb. Even assuming the arc position were perfectly
matched-up with the filament position, the nature of the light from an HID
capsule is such that the resultant beam pattern will usually produce very
much excessive glare to oncoming drivers and backdazzle to the driver in
bad weather, and will fail to illuminate properly the places in the
driver's field of vision that really need to be illuminated.

The folks pushing these "conversions" assure their customers that it's not
particularly crucial to get the source position exactly right. I'd like to
think that's because they simply don't know any better, that they consider
any piece of glass with light coming out a "headlamp"...rather than to
think that they're simply placing their personal profit over your highway
safety.

Perhaps most dangerous of all, these "conversion" pushers casually dismiss
the fact that if you install one of their "conversions" in a system where
the original headlamps produce both a high and a low beam, you will not
have a high beam after the "conversion"! The pushers claim that a high
beam is "not necessary" with HID headlamps. This is certainly quite wrong
both from a legal perspective and a safety perspective. A low beam
headlamp, no matter how bright, is a low beam headlamp, and cannot
substitute for high beam.

----------------------------------------------------------------------------
----

Now for the technical nuts 'n' bolts for those who want to know exactly
why it won't work:

----------------------------------------------------------------------------
----

"retrofitting" an HID arc capsule in place of a filament bulb is a very
poor idea. There are lots of folks out there advertising "retrofits" of
this type. In a nutshell, it is sometimes possible to physically adapt an
arc capsule to go where a filament lamp was meant to go. It is really NOT
possible to attain an acceptable (let alone compliant) beam pattern this
way. Some of the "retrofits" get kind of close with regard to cutoff
gradient and relative light levels within the beam, but most all of them
have beam problems...improperly placed hot spot, dark spots in the center
of the beam, excessive foreground illumination, excessive stray (glare)
light, improper cutoff placement, etc.

It is, as I say, sometimes possible to place the arc in the headlamp
exactly where the filament was located before. However, an arc is a
fundamentally different *kind* of light source than a glowing filament.
The reflector and/or lens optics in a headlamp meant to take a filament
lamp are designed specifically for the characteristics of a glowing
filament.

Many optic designs rely on the edges of the filament to shape the beam
pattern, for instance, and there is no reason for chromatic correction to
be worried about, because in most filament-lamp headlamps, chromatic
aberration is not a problem. (Some polyellipsoidal optics do exhibit
substantial prism effects at the cutoff.) The boundaries of the arc in an
automotive HID capsule are much "fuzzier" (to use a technical term!) than
the edges of the filament in a filament bulb. There are substantial color
differences at different points in the arc (the edges, the ends, etc.),
while the color of a glowing filament is relatively uniform. The arc is
usually not the same length as the filament. For all these reasons, it is
not reasonable to expect an acceptable beam pattern just because the arc
is placed in the same location as the filament was.

Note that this does not even address the issues raised in lamp designs in
which the filament is not coaxial with the bulb base (9007, NDF/9008) or
in which the filament is transverse rather than axial (H3) or transverse
AND non-coaxial (9004). All arc capsules (D1, D1S, D1R, D2, D2S, D2R,
9500) have axial arc paths that are coaxial with the base. This does not
stop "headlamp mercenaries" selling "conversions" for such headlamps. The
resultant mess cannot be called a beam pattern, but as long as the
"converted" lamps spray-out lots of purplish light, the purchasers of such
"conversions" tend to be happy, not knowing and/or not caring that they
are driving with dangerous, overly-glaring, inadequately-performing
headlamps. ESPECIALLY if the seller of the "retrofit" has given
ill-informed (or just plain fraudulent) assurances that the kit is "beam
pattern corrected". There's flatly just no such a thing!

Most people do not have the expertise (let alone the equipment) to judge
the acceptability of a headlamp beam pattern. Most people can tell the
difference between arc light (purplish) and halogen light (not purplish).
It is certainly possible to physically place an arc capsule into a halogen
headlamp. But for all real purposes, it is NOT possible to make an
acceptable headlamp this way. For some cars, legitimate HID retrofit kits
are available. These consist of complete new headlamp lens-reflector units
to go with HID capsules and ballasts. This is the *ONLY* safe and proper
way to put HID headlamps on a car not originally so equipped. "

On Tue, 9 Jul 2002, Kenneth Chang wrote:

> Has anyone installed any HID lights in their Ur?  I'm thinking about some
lltek motorsport HID Xenon upgrade kit.  Has anyone tried this?
> Ken
>
>
> S4audinut at aol.com wrote:
> >
> > --
> > [ Picked text/plain from multipart/alternative ]
> > In a message dated 07/09/2002 3:28:06 PM Eastern Daylight Time,
> > Jimmy at texasbankers.com writes:
> >
> > > That page must have got hammered.  Even the link from their home page
> > > doesn't seem to work.  Oh well, it looked like the legit Audi press
> > > release,
> > > so there will be other links soon.
> > >
> > > Try this one:
> > > http://www.germancarfans.com/news.cfm?NewsID=2020709.001&Page=2
> > >
> > > Jimmy P.
> > >
> > >
> > >
> >
> > I think it is ugly, but I havent liked anything they have put out since
the
> > TT and early (not our)  a4. Hyaundi and Kia seem to be building better
> > looking cars than most of the big makers. OH well.
> > Rod
> > _______________________________________________
> > S-CAR-List mailing list
> > S-CAR-List at audifans.com
> > http://www.audifans.com/mailman/listinfo/s-car-list
>
> --
>       	  Kenneth Chang
>
>           Sun Microsystems, Inc.
>           500 Eldorado Blvd, UBRM01
>           Broomfield, CO 80021
>           Email:kenneth.chang at sun.com
>           Phone: 303-880-0180

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