Apparently at some point my car was in a minor front right accident ... and the jerk who fixed it saved a few bucks by replacing the headlight with a halogen model....

Well, I never noticed anthing wrong when I bought it, and later looking at the pathetically weak passenger side headlight I just figured the d2s bulb was going bad... so I bought a new one and went to replace it, only to find a halogen 'projector'... Further inspection found the ballast to also be missing... it really was a whole hallogen headlamp *downgrade*....

So, logically, I decided to fix this issue.... At that moment on ebay there weren't any decent deals on 2000/2001 xenon lights. As you probably know if you are reading this, up through 2001 standard xenons were used, and then in 2002 bi-xenons came around. Unfortunately, the two light assemblies differ in several important way: different overall shape (straight drop-in not even remotely feasable) and entirely different projector / lens internals. Specifically, the 2002+ bixenon units are substantially larger than their single-xenon 2001&below counterparts.

Without no easy source of a drop in 2001 xenon replacement, I made the decision that I wanted bi-xenons. Why not, i asked, they are just better! Not to be outdone, (or just without thinking...) I hoped on ebay and bought a pair of 2006 a6 bixenons w/ hardware. The hardware worked, but one of the lenses was broken beyond repair, so I got a pretty good deal.

In typical fashion, I had just signed myself up with more than I bargined for Here's a before & after :


my car torn apart,


the modified lights about to go back in,


and the (not yet aligned) final product (low beams)...

 

The two units looked similar size online, so after removing my lights I tested the slight chance that they might fit anyway... well, I did know it was 'slight'...

So, same company, same model, just one yr diff - just bolt in the new projectors ? NO.


wrong length


more wrong length


and more...


wrong diameter as well... (the 2002's are larger diam)





looks like FUN!!

 

worth a try anyway.

I did manage to fit the 2002 unit into the 2001 housing - backwards & with some pushing - but it was wasted effort as the two projecters are way different...

It's hard to tell but the projector doesn't even come close to being a bolt-on.

 

My next idea was, what if I could use my housings but with the 2002 lens & silver internals? Well, since I had some extra housings (the 2002's) i decided to find out.

It was impossible to get the silver plastic out of the '02 intact... so I had to cut off the clear cover with a cuttoff wheel... However, since I couldn't destroy the 2001, i would need a way to get the housings apart *intact* ...

NOOOO amount of prying, gentle heat-gun use, etc would separate the lens from black plastic main body.... I remembered some suggestions people had offered when I needed to fix a leak on my old lexus sc, so I went to the oven to try to heat the whole thing up... Now, if someone really took some time and did this right I suppose it would work... I have seen legitimate looking tutorials of such online. The adhesive supposedly has a **slightly** lower melting temperature than the lens. Regardless, I was in a hurry and in minutes flat did this: :-)

*Good* thing it was scrap anyway.... while I'm at it, I should warn you not to clean the silver internals with alchohol...

 

so, this project would require some real effort. Sometime later (hopefully sooner) i'll be the proud owner of a mill & lathe, but for now I am not, and it would have been a pain to port all the stuff over to school. So this turned out to be an interesting process.

Basically, while the general form of the 2001 & 2002 projectors was the same, the lens' diameter, length, and bolt pattern were different, as were said dimensions of the lens half of the assembly.

I wasn't (well, decided I couldn't be) too concerned about total length, since I figured I would just cut a hole in the black rear-cover & somehow weld on some more plastic to accommodate the 2002's being so much longer overall than the 01's... thankfully it ended up fitting fine, but with no way to test-fit and no motivation to model it all in Catia, I assumed the worst.

 

The 2002 had some extra bulk, as well, in the bixenon-part, which if your not familiar with is just a small solenoid which literally moves a piece of sheet metal up & down in the 'image plane' (a physics/optics term), which by design lays at the front of the lens portion of the assembly. In the standard xenons, none of the extras are there, just a fixed piece of sheet metal with the slight s-jog in the middle. The pic here *is* right-side-up. The lens inverts the image (in all directions ie up->down, left->right) . As shown, it is in the low-beam configuration.

If the picture was taken on-axis with the light, you could see how the cross-piece i'm talking about here is straight and horizontal, with one half at one 'height', a small jog right in the center, then the other half at a lower height.

This whole thing blocks a lot of the output of the hid bulb - it exists to keep your lights out of the eyes of oncoming traffic... It is a shame that there aren't any clever designs to eliminate the need for this. I imagine it would be possible to at least make the reflecter such that much less are needs to be blocked, but that would be a lot more complicated of a reflector... who knows. anyhow, as it is now this plate does block a substantial portion of the output... It covers nearly half of the area of the image plane, is approximately coincident with the axis of the bulb, and since the reflector is roughly a symetrical oval it appears that this plate removes somewhere near half of the output!

Also, I don't seem to have any pictures of it, but there was nother aluminum sheet metal sheild on the top of the reflector... about 2 sq in, right on the roof. I removed it. This will only prove detrimental if it was there as a heat shield for the thermoset plastic reflector. I made the educated guess it just removed a part of the output, and I had enough of the light-removing stuff



two views of the bixenon


2002 bixenon on left, 2001 on right

 

So on to modification...

In case it wasn't clear previously, the details of the problem force me to use all the 2001 housing parts along with the 2002 projector assembly (the lens & reflector).

First, enlarge the hole to fit the larger '02 lens diameter. I used a air die grinder and dremel, and a lot of care. As you can see in pic1 towards the upper left, I had to grind a tiny bit off to eliminate some slight interference.



ground out


and it fits! (pic from what would be outside the front of the car)

 

Next, figure out some way to bolt the 02 projector into the 01 housing. As before, the depth & hole patterns are completely different. In the previous post you can see the 02 lens set in its final position in the enlarged hole to the front. The 01 lens & reflector would line up with the bolt posts you see.

The two problems are the needed attachment points are in different positions in both the horizontal and vertical directions. The 02 lens & 02 reflector will obviously have to stay in their original positions relative to each other, as they have a specific optical design.

My solution? God I wish I had a mill handy... so in ~ghetto fashion I fabricated a bracket that would bolt down where the 2001 assembly would have been, and then provide the same bolt locations that the 2002 assembly had in its original unit.



the end result. actually looks kinda nice... [all for pieces shown, two for each side. The projectors are bolted on by three bolts each.]


my 'jig' to bend the radius's.


after bending


tap some steel to back the aluminum, providing a place to bolt the 2002 to, without needing to hold a nut when installing. More on this later.

 

It turns out that it was a little easier to modify the 2002 reflector for a new bolt hole, finally using that new hole + two of the original locaitons. in pic1 here you can see this mod partially complete. (I re-used an artifact in the units original mold pattern to make a new bolt hole...)

As you can see in pic2 here I also had to make a pair of cutouts for the 2001 bolt studs... this seam less risky than trying to cut them off to length while still inside the housing.

Note the epoxy build up in pic1. It would *really* suck if these things broke after I finished & installed everything.

On that note, I painted them black to look cool... no seriously, though, as I might have already mentioned, there was a 'mystery-light-deflector', a separate small piece of sheet metal that I initially thought was a non-reflective part to dim the output.... (so I left it out of my build entirely)

there is a distinct possibility that that was indeed present as a heat shield... perhaps durr=ing testing VW found that the roof of the reflector part would get too hot, potentially melting, and rather than re-design it all Hella (the oem for these projectors, i believe) added this small shield. So the black should radiate heat a lot better than the previous metallic silver, hopefully keeping it cool enough not to cause me a major headache. (Note: 2 years later (2010) as I fix the links to the pictures not probs!)





epoxy reinforce. the horizontal cut you see is part way through new hole I'm using for my bolt pattern.


always prep the surface to increase the chance the epoxy will make a good bond.

 

And with the custom brackets installed...

behind the two holes visible in both shots is where that small steel piece I tapped (threaded) earlier will go. This way, I just have to get it started, and since one piece holds both bolts, I don't have to get a wrench in there on it, (ie it can't freely spin like a nut would, requiring me to hold it while I tightened the final assembly in.)

in pic2 you can see that I didn't make the funny shape just-for-fun... (i'm holding a deep socket) This was the only way I could get a driver in there to tighten my bracket down to the 2001 bolt holes.

notice how the bracket fits exactly underneath the lens frame, thus the lens and reflector can mount directly together, preserving their designed function.