FromDate: Tue, 6 Jun 2000 10:19:08 +0100 From: "Hunter Johnson" <HJOHNSON_at_dbmail.debis.de>
Subject: Re: Euro Lights (long)

Jim E says:

"For some unknown reason (at least to me) the ZKW were never used on the M3 coupe - neither the 3.0 or 3.2."

Jim B says:

"Would the coupe lights be different than the sedan? Just wondering, since the Euro lights I have on my car are ZKW (purchased from Bekkers Imports, IIRC)."

Jason says:

"I saw some strange lights on Kelly wollenbergs car once. Looked like US headlights, but were glass. She ordered them when she did euro delivery. So they arre US dot glass lights. maybe you got one of those..."

The early Euro E36s came with polyellipsoidal low beams, which were replaced 5 years ago with what Jason calls "looked like US headlights but were glass".

The polyellipsoid system works like an overhead projector, with the bulb at the first focus of the ellipse and the screen which produces the sharp horizontal cutoff positioned so that the funky semi-spherical lens projects it onto the road. The "poly" part of the polyellipse means that the reflector shape is two different ellipses, one shape for the vertical cross section, another for the horizontal cross section. This way a lot of light is dispersed from right to left, but not so much dispersal happens from top to bottom.

The newer headlamps are Free Form (Hella's term) which means that a computer is used to calculate the shape of the reflector given the bulb position and the desired beam pattern on the road. This technology was used on ALL US E36s, although of course the ECE and DOT beam patterns are different, so these units are different. FF lamps are much more efficient than the polyellipsoid system (if there is a screen, then some of the light is hitting the screen and not getting to the road), although personally I prefer the Polyellipsoid since it focuses the light more intensely.

On all E36 headlamps the high beams are probably simple parabolas.

One of the other differences between DOT and ECE lamps is the use of glass vs. polycarbonite for the outer lens. The DOT has strict rules about the watertightness of the headlamp assembly, and the ECE lamps often fog up from poor sealing. However, the DOT lamps' plastic also get sandblasted after several years of use and this messes up the ability of the light to get out, requiring replacement of the entire headlamp to return to 100% performance. The ECE unit's glass outer lens can be replaced for around $60.

The difference between a Bosch, Hella or ZKW headlamp unit designed for the E36 is probably nonexistent, although these suppliers will probably tell you otherwise.
The fact is, BMW specifies the headlamp beam pattern (at the suggestion of the initial supplier), and from there on the subsequent suppliers have to meet this criteria. One exception, however, may be that if ZKW wasn't an OEM supplier,
their lamps might be inferior (i.e. insurance replacement but never specified on new vehicles).

Personally I believe that while there is still a difference between the BMW ECE and
DOT headlamp, with the next E46 this difference may be non-existent -- about 5 years
ago I changed the lamps on my 300TE Mercedes-Benz from DOT to ECE and gained very
little performance. The ECE and DOT have been working over the past 5 years to achieve a homogenized headlamp pattern for use world wide, and while they're
not there yet, the ECE pattern now allows more light above the horizontal than they
used to, and the DOT lamp has a blend between a simple "hot spot" and a horizontal
cut off, and I don't doubt that as the age of the motoring public in the US continues
to creep up, the DOT will get more and more complaints about headlamp glare, requiring
a more European-style beam pattern in the US -- especially given the advent of gas
discharge bulbs, which throw twice the light from 2/3 the power.

That said, please keep in mind that a properly aimed ECE lamp (1% drop) has a range of
60 meters, so at 60 mph you are out driving the range of a European headlamp (60 mph =
45 m/s, so 60 m = 1.3 seconds). The DOT lamp which throws light above the horizontal
will therefore have a much greater range.

However, I find that the ECE high beams are superior to the DOT highbeams, even though
they might be simple parabolas.

John F. will surely want to comment on all this, since both of us live in Germany,
but my impression is that neither of these systems are optimal. My recommendation
regarding retrofitting ECE lamps to your car is that first try to reaim the DOT lamps
so that the hot spot is directly in front of the bulb, instead of down and to the right.
Also, raise the beam so that the horizontal cutoff is at a 1% drop from the bulb, per
ECE specification (that is, if the bulb is 60 cm above the ground, and the car is parked
10 m from a wall, then the horizontal line should be 50 cm above the ground).

If that doesn't do it for you, then try the ECE lamps, but I would go the extra mile and
install the Euro spec headlamp adjuster. This has four settings: 0, 1, 2, and 3, and I
believe that they correspond to the % drop, so "1" is the normal setting. By adjusting
your new Euro lamps correctly you can dramatically increase the range of the lamp by
moving to "0" on the fly, and dropping back to "1" when you encounter traffic on the
highway. The "2" and "3" are used if you have lots of stuff in the trunk, which causes
your headlamps to shine upwards.

Hunter
1998 M3/4 with Euro lamps, no adjuster