Headlights

[Roger M. Woodbury]

This headlight issue is a constant one on this list, but not only here, but
on others as well.  There is a continual misunderstanding about what light
is and how it works, which is compounded a great deal by the assumption that
most of us over the age of 30, (I mean, there ARE a few of us on this list
who are over thirty aren't there?) just assume that our eyes are not as
sharp as they once were.

But the real truth is that the design of the DOT approved headlight dates
to, oh, sometimes in the 1940s.  Then the true, state of the art, was the
tungsten filament, sealed beam bulb.  That DOT standard has been updated,
but little or not attention has been made to actual beam pattern development
in the DOT design.  Hence the light output pattern necessary in DOT approved
bulbs is basically the same as it was back before a lot of us were born.

Hence the principal concern is for light output in the face of oncoming
drivers, as well as those drivers who you are following in traffic.  US DOT
automotive standards are primarly directed at where the majority of drivers
are, and that is in the urban environment.  Since there is a lot of ambient
light in an urban environment of any sort, the requirements of automotive
lighting are significantly lower than in the rural environment where there
may be no more than one streetlight per half mile or less.

So, in the case of the 5000/200 series cars, the headlights were made to
comply with the minimum standard to insure DOT acceptance, and they are by
design, and will ALWAYS be, inadequate for driving anywhere but in the major
urban areas.  You can put relays, heavier wires, higher wattage bulbs and
magic pixie dust into the standard DOT headlamps, and while you will make
them brighter, you will only be making an inferior, inadequate headlighting
system brighter.

The difference is in the beam pattern.  The lens design of the European
headlamps is totally different than in the US DOT headlamp.  The DOT
headlamp produces a sort of inverted bowl shaped pattern, with the top of
the bowl at the hood of the car, and the beam sloping off radically in front
of that.  There is little difference between the low and high beam in these
lenses, except that in high beam the light is thrown forward and upward a
small amount.  The light diminishes as it reaches forward, as it is
unfocussed, really, being primarily a  big blotch of light to be used, when
the low beams don't light up the next street sign well enough.  The US DOT
high beam is not intended for continual use, as the "main" beam is the what
we called "low" beams.

The European headlamp theory is totally opposite.  What we call low beams,
are in fact, "dipped" beams in Euro parlance, and our "high" beam is their
"main" beam, or principal driving beam.  Their theory is that on the open
road, what is needed is a large mass of really intense light thrown out to
the point of maximum visibility of the driver and the braking ability of the
automobile from the maximum allowable speed on most roads.  Dipped beam is a
very finely directed beam, with fairly little light allowed to the left of
the front of the car, and this light drops off quite radically ending at the
edge of the left side of a two lane road.

The beam pattern is strictly controlled in a flat line across what would be
the bottom of the rear window of a car being followed, and that line extends
most of the way across the road side being travelled.  This is very good in
traffic, for instance, as halogen light is quite bright, but although the
Euro lights may be bright on both high and low beam, with the beam pattern
ending below the bottom of the rear window of a car being followed closely,
or stopped behind at a traffic light, the other driver won't notice.

On the right side of the travel lane, the European headlamp pattern makes an
abrupt rise to the right (45 degrees).  This provides striking illumination
for objects on the right side of the travel lane, as well as the breakdown
lane or road shoulder.  Hence, the bicyclist, pedestrian, or occasional
moose on the right side of the road will be lighted with the E-code lamps,
but with DOT lamps you might not see them at all until you were alongside of
them.  (If you saw them at all).

In the 5000/200 Audis, the highbeams illuminate about the area of a football
field.  When I installed my headlights in my 200, I relayed both high and
low beams at the headlamps, bringing new power to the new bulbs by using
heavier wire directly from the power point on the right side of the engine
bay.  In my case, the entire process was accomplished at my friendly Audi
dealer....I carried in my bulbs and had them do it, while I stood by and
watched, provided an extra pair of hands and so forth.

I live in rural Maine, and knew that this was a mandatory change.  I own
several properties and need to be able to drive some distance on short call
at odd hours, so I knew that I would be apt to need better lighting in
whatever car I drove, so I made the change to the Ecode lamps. Total cost
including labor was just south of a thousand dollars when I was done.  The
difference was astonishing to the extent that until one tries it and sees
it, it can't be believed.

The truth is that for most drivers, they are not necessary.  Most drivers
spend time driving where there is at least some ambient lighting, and some
traffic.

But for those who live and drive every day in rural areas where there are
few if any streetlights, and every corner isn't brightly lit by a
Seven-Eleven, there simply is not substitute.

Roger
1994 100CS Quattro Avant (standard headlights)
1993 V8 Quattro (standard headlights)
1997 GMC 3/4 ton 4X4 Standard headlights that are so terrible as to not be
believed.

P.S. I have also had Euro code headlights in the Mercedes 190D Turbo that I
bought in 1997.  These were a dealer ordered and installed option (!).
These were necessary because the US DOT 190D headlamp assembly, as was
almost all Mercedes models in the 1980s, was a flawed design.  The
rectangular, 7" sealed beam halogen headlights that were approved for use by
DOT, were recessed in the assembly.  This recess would allow snow, mud,
dirt, ice etc, to accumulate rapidly, reducing illumination by half
sometimes within a couple of miles of driving.  The Euro lamps were made the
headlamp surface flush with the front of the vehicle, so in addition to
providing far superior beam pattern and throw, the accumulation of road crud
was far, far less.  I was driving around 50,000 miles a year in my business
at that point, and a lot of it was in the severe dark of the rural north
woods, and I can absolutely guarantee you that on of the worst experiences
to have is to have to drive around a hundred miles to get home, after it has
started to snow, and to have to stop the car, and get out and clean off the
headlights every ten miles or so, because that xXZCCXXX logging truck had no
flaps on his rear wheels and he just COATED you with road slime.  The Euro
headlamps cut the interval by about half.  Worth the money then, for sure,
as there were no headlight washers....