2-Piece to 1-Piece Headlight Conversion

[CCA4]

Hey guys,

I just got done doing the 2-piece/1-piece conversion on my '97 A4, and also added HID's, so I thought I'd turn the pics I took into a DIY, since I never really found a good one when researching. So here goes:

DISCLAIMER: I take no responsiblity for the terrible things you might do to your car after reading this post, it's for informational purposes only.

Tools I used:
-Dremel with a cutoff wheel bit
-Angle grinder
-A set of Torx head sockets
-Soldering gun, flux-core solder and shrink tube
-Clear Silicone
-Files, ratchets, wrenches, and other assorted common tools

I also purchased DEPO 1-Piece projector housings on E-bay, and an 8000k HID kit from VVME and was more than pleased with both.

Ok here's the rundown. The 96-98 A4 came from the factory with (ugly and inefficient) two-piece halogen headlights. Starting in 98.5 they upgraded to projector housings with xenon lamps. This is a pretty basic step-by-step guide to converting your 2-pieces to 1-pieces. Lets get started:

The first thing you're going to need to do is remove the bumper. The front bumper cover is held on by 2 or 3 torx head screws on the inside of each wheel well, and two long torx head bolts in the front. The screws will be easy to spot, evenly spaced along the front of either wheel well. The two bigger bolts are oriented vertically behind the left and right lower grille inserts. If you yank the grilles out you should see the bolts. They're pretty big torx heads, but if you plan on owning your Audi for a while, you should be the proud owner of a big set of torx sockets anyway. The stock headlights are held in by 4 torx head bolts; two on the top, two on the bottom. The two on the bottom are inaccessible with the bumper on, hence step one. When you get all set up, it should look something like this:
http://i316.photobucket.com/albums/mm323/christopercook7/SNC00052.jpg
Below is the part of the fender you're going to need to trim off. I've heard of guys using a Sawzall to do the rough cut, but I wasn't feeling that lucky...
http://i316.photobucket.com/albums/mm323/christopercook7/SNC00053.jpg
I suggest you tape off the part of the fender you don't want to cut, just to keep the hot chips and sparks from messing up your paint. Start by cutting a little at a time, test-fitting the light as you go. It will take longer this way, but if you cut too much, you'll be screwed and need a new fender, so better to take your time. When I was done cutting, my fender looked like this:
http://i316.photobucket.com/albums/mm323/christopercook7/SNC00054.jpg

I did the rough cut with the Dremel, cleaned it up with a grinder, and finished it off/removed burrs with the files. I can't stress enough here to TAKE YOUR TIME.

Test fit the lights one last time, the rubber around the corner light should be tight to the fender like this:
http://i316.photobucket.com/albums/mm323/christopercook7/SNC00055.jpg

Repeat this process on the other side, and you're done with the hard manual labor. The next step is to wire in the new headlights. This step is complicated by the fact that the stock lights didn't have ballasts, the HID's do.

I decided to cut the stock wiring harness off inside the stock headlights. Another option is to cut the wiring harness off just behind the plug that goes into the stock housings, and use a multimeter to check the wires. By that I mean, turn on the low beams, and use the volt meter to see which wire is hot. Then repeat to find the high beams and fog lights. Either way, the hot wires for your low beams should go to the ballasts for the HID's, then back to the HID bulbs. The high beams can be transferred straight into the new housings, and the fog lights will have to be moved (since the 2-piece housings have integrated fogs and the 1-piece do not).
Cut a hole in the back of the housings to allow for the new wiring setup, something like this:
http://i316.photobucket.com/albums/mm323/christopercook7/SNC00065.jpg

#1 is the access panel behind the projector lense. The large black wire and the black and red mesh go to the ballast, part of which can be seen in the foreground at the bottom right corner.
#2 is the stock wiring harness, which i covered up and re-routed through the access panel behind the highbeam bulb

For now, I just taped off the fog light leads (black wire on mine) to be used later. The HID kit from VVME came with a pretty good set of directions and a wiring diagram, and was reasonably priced. If you're going HID I'd suggest using them. Place the ballasts as far from the motor as is practical, they don't like getting hot.
http://i316.photobucket.com/albums/mm323/christopercook7/SNC00062.jpg

http://i316.photobucket.com/albums/mm323/christopercook7/SNC00063.jpg

The above pictures are where I chose to mount the driver and passenger side ballasts, respectively. The driver's side is mounted on the plastic shield covering the P/S fluid reservoir, the passenger's side is located just forward of the second firewall, just behind the air box.

Here's the end result:
http://i316.photobucket.com/albums/mm323/christopercook7/SNC00057.jpg

http://i316.photobucket.com/albums/mm323/christopercook7/SNC00058.jpg

If you have any questions, comments, or would like me to add or remove material from this DIY, PM CCA4 and I'll talk you through it. Thanks guys!

[ImTheDevil]

Looks great and very nice work on the trimming on the fender. Love the plate too:)

[CCA4]

Love the plate too:)

Haha thanks man. I've been gettin mixed feedback about it, but I like it so f*ck 'em :tongue:

Anybody think I should add or change anything? Cincy said he's gonna move this to the DIY section, but I haven't checked yet.

[ImTheDevil]

Two comments:

1 - in the paragraph about the stock lights you said the projectors started in 98.5 but facelift was 99.5 (typo I assume)

2 - I'm curious about the four bolts holding the light in - mine only had 3. Two at the top and one on the outer side down low which is accessible with the bumper on. Maybe that was a 12v vs 30v thing? Regardless I agree with pulling the bumper when grinding - that's a no-brainer:)

Sounds like a winner and worthwhile addition to the DIY section. FWIW I don't know each wire in the headlight harness offhand but the green/yellow is the fog wire and the custom on German cars is to use brown for ground wires. Just a tidbit:)

[CCA4]

re: #1, yep..typo. Good eye ;)

As for the 3 bolts vs. 4 bolts, its funny you should ask that. The new 1 piece headlights only had mounting brackets for three bolts. The 2-piece jobs I took out had four, the two obvious ones on top, then two on the bottom side of the housing: one on the inboard side of the headlight, oriented perpendicular to the center line of the car, and one on the outside of the housing, also perpendicular to the center line. The one piece headlights were missing the mounting bracket for that 4th bolt. They don't seem to be any less secure than the 2 piece lights i took out, maybe Audi decided 4 bolts was overkill?

Good tidbit, I cut everything off inside the headlight housing because I was too lazy to figure out what went where before that plug :lol:

[ImTheDevil]

Yeah that must be it. Mine only had 3, and where your fourth bolt was mine had a guide peg that went into a rectangular eyelet on the lamp housing.

[CCA4]

For the record, guys: The driver's side ballast might be mounted a bit too close to the engine. I went back through and re-checked all my connections yesterday and the label on that ballast had peeled off and shriveled up from the heat comin off the header on that side :eek:

I would probably try to find a better place to stick this one if you decide to do this conversion.

[ImTheDevil]

In my car the driver side ballast is between the ABS module and power steering reservoir. In a friend's car before we put the light housing in we mounted it to the bottom of the crossbar below the headlight. It was kind of a pain but it's protected there and very clean to look at. I'd do one of those two options.

[CCA4]

Thanks for the tip man, I'll check that out this weekend

[Cincy]

Just picked up a 12v to daily and the headlights are just terrible. Going to have to do this process sooner than later on it to be able to see as clearly as i do in the TT. Just not happy i dont have lower fogs but may still try to add in some bright yellow hid's for them also.

[CCA4]

Yeah I didn't realize how terrible the lights were until I swapped them out. You might try one of those headlight restoration kits in the mean time?

[Cincy]

my lenses are clear, just the output is weak compared to my TT. I drive with the fogs on to make up for them.