GMT400 projector retrofitting

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GMT400Tahoe

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THIS THREAD A WORK IN PROGRESS, NOT YET COMPLETE

This is a build thread to document the projector retrofits I have built for my GMT400 platform Chevrolet Tahoe. There is information regarding two different retrofits in this thread:

  1. Budget build that I did as a proof-of-concept. This allowed me to see if I could do it without wasting too much money if I could not complete the project. This was moderately difficult but manageable.
  2. A high-end build that I did with the best components. Once I knew I could do a retrofit on these vehicles, I wanted to build another one with the best parts. This build was more difficult because the high-end projectors are generally larger and even more difficult to fit in the shallow GMT400 headlight housings.

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The budget build installed on my 2000 Chevrolet Tahoe Z71. Yellowstone National Park.


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The budget build installed. Xenon low beam illuminated. DRL still activated but receiving full power from relay harness instead of reduced power from vehicle wiring.

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The budget build installed. Illumination of both bi-xenon high beam and halogen high beam via 4 high mod.

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Close-up view of the budget build installed. Notice defluted area in lens directly in front of projector.

Purpose:
Without going into too much detail, a projector retrofit is really the only way to correctly do high intensity discharge (HID) lighting.​

Plug-and-play (PnP) HID where bulbs are thrown in reflectors or projectors made for halogen lighting result in scattered light that does not provide an improvement in functional light output and scatters light in directions that blind oncoming drivers. This is because the source of light in a halogen bulb is at a different location from the source of light in a HID bulb is different still from the source of light in a light emitting diode (LED) bulb. The net result is that PnP HID or PnP LED provides a decrease in functional light output relative to simply a good set of halogen bulbs in reflector housings. People think their PnP HID lights are providing better light output, but in reality the hot spot of light that illuminates down the road is actually decreased and everyone else on the road thinks they are a turd with the blue light they scatter in all directions (unfortunately back before I learned about projector retrofitting I used to be one of those annoying drivers when I had a PnP kit on my old Tahoe).

In contrast, installing a projector that is specifically designed for HID can provide the desired increased light output that is properly controlled and focused on the road, all while preventing the blinding of oncoming drivers that is associated with PnP.

An additional benefit of projector retrofitting is that many projectors are bi-xenon, indicating that the shield within the projector that generates the desired sharp cutoff can be moved out of the way when the high beams are activated, allowing the same bulb and projector that function primarily as a low beam to instantly provide high beam illumination. In order for the bi-xenon function to work on our GMT400 platform vehicles the 4-high headlight modification must have already been completed. The 4 hi mod is an easy modification that allows the low beams to remain illuminated when the high beam is selected, good information on that found in the following 1,2,3 posts.​
 
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GMT400Tahoe

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Retrofit 1, a budget-minded retrofit:
The first retrofit I completed was a budget build to see if I could do it. It was successful and provided a massive lighting improvement for my vehicle. For my first retrofit I defluted a spare set of OEM headlight lenses to allow the projector output to pass through the lens unobstructed. This involved using a drill press to slowly sand down the fluting until the inside of the lens in front of the projector was flat. I did a poor job documenting my work on this retrofit, but I will share what I have.

Parts:

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Acme standard mini H1 bi-xenon projectors
: for properly directing HID light. Notice bulb type is H1. Also notice projector is bi-xenon, which allows for use as high beam in addition to normal use as low beam. Budget priced at only $20.00


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Ballasts/ignitors
: necessary component for igniting HID bulb
4500K HID bulbs, H1: good OEM color, provides best light output. Bulb type is H1 to fit projector.
HD wire harness: necessary for multiple reasons. First reason is that allows increased current necessary to ignite HID bulbs to pass directly from battery to ballasts instead of through vehicle wiring not meant for large current. Second reason is allows the HID system to continue to be run as DRL, because 12V provided from battery using harness instead of the decreased voltage that the DRLs run at. Decreased voltage causes numerous problems for HID such as flickering bulbs and damage to ballasts/bulbs.


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High beam splitters: Necessary to activate bi-xenon shutter and still retain halogen high beam. Allows both halogen high beams to illuminate and bi-xenon shutter to drop. Effectively creating quad high beams. Note that bi-xenon operation requires prior completion of the 4-high headlight modification in order for the HID bulb to continue to receive power when high beams are activated. Notice I accidentally purchased quantity of two, but only one was needed because each order provides one pair.


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Capacitor
: Purchased to prevent the flickering that is sometimes observed when switching from low beam to high beam when 4-hi headlight mod is run on GMT400 vehicles.

All items for my first retrofit were purchased from a great website for projector retrofitting called The Retrofit Source (www.theretrofitsource.com). Notice the total cost for everything needed for this budget build was $190.00. So everything necessary to do HID correctly does not have to be prohibitively expensive.

For my second retrofit I purchased from another great website called Lightwerks (www.lightwerkz.net). The reason I made the purchase from them is because they do a great job providing YouTube videos on installation tips, product comparisons/reviews, and information about DIY retrofitting. I found their videos very helpful in brainstorming how to complete my high-end build, so I purchased from them for my second retrofit. You can't go wrong with either of these two retailers.
 
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GMT400Tahoe

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Retrofit 1, a budget-minded retrofit (continued):

Installation:

The following are the steps I took during the building of my first retrofit. It was a learning process and there were several aspects I would do differently given my current level of knowledge (see step 6,7 for examples). Therefore use these steps as a general guide, but not a definitive step-by-step instructions for performing your own retrofit.
  1. I strongly suggest any retrofitting project be done on a spare set of headlights. A few reasons for this are that if a mistake is made it does not leave you without headlights on your vehicle, you do not need to be rushed to get them back on the car, and it is good to keep a spare set of the OEM halogen headlights in case of selling the vehicle or needing to pass a vehicle inspection, etc.

  2. GMT400 headlight housings are so shallow that even the smallest projectors such as the mini H1 series of projectors will not fit within the housing. The projectors are much deeper than the headlight housing. Therefore much of the back of the reflector housing needs to be removed in order to make room for the projector. The first step in the process was simply removing the reflector from the headlight mounting hardware. This was more difficult than it sounds because the adjusters need to be removed from the headlight as well, and they were very firmly attached via brittle plastic snaps to the back of the reflector housing. The plastic of the OEM housings I was using was brittle and fragile. Be careful not to break the adjusters during this removal process because they will be critical for headlight aiming when the projectors are installed.

  3. Once the reflector portion of the headlight assembly is removed from all of the other components, use a marker to draw a few reference lines on the back of the housing. Basically want to keep a reference for the directions up/down, left/right and front/back for the housing. It is important to do because the GM400 headlight housings are angled slightly, so if the projector is accidentally mounted perpendicular to the lens it will be pointing in a completely wrong direction.

  4. Since I was using OEM housings, the lens is pretty permanently attached to the housing using a permanent adhesive. That coupled with the brittle plastic means that no amount of baking is going to remove the lens from OEM housings. But since the projector is so much deeper than the housing and requires cutting of the back of the housing, the lens does not necessarily need to be removed. This is in contrast to aftermarket housings, such as the Spyder manufactured glass lens housings that are popular on this forum. The lens on those housings are held on by a butyl adhesive, which readily can be removed with heating either from a heat gun or in the oven. The budget minded retrofit detailed in this post shows how to retrofit the OEM housings without removing the lens. In a later post I show how I removed the glass lens from the aftermarket housings for the high-end build.

  5. Once reference lines are drawn, remove much of the reflector by cutting away from the rest of the housing. I used about a 2 inch hole saw to make the first cut and then used a dremel to cut any further material away. Make sure that you only remove as much material as needed so that the projector can fit through from the back of the housing. Do not remove more material than necessary.

  6. When the projector can fit through the hole cut out in the back of the reflector, the fluting on the OEM plastic lens needs to be cleared out in front of the projector. I used a drill press with a series of increasingly fine 2.5 inch sanding discs to smooth out the surface. When I finished sanding I buffed and polished the lens until it was smooth and clear. This was a really tedious process and it was difficult to reach in through the hole in the back of the reflector to buff and polish the surface. It also required a thorough rinse with water when everything was finished in order to clean the debris from inside the headlight housing. After going through this tedious process, I recommend that unless someone is absolutely set on using OEM lenses, much of the trouble in this step can be avoided by purchasing clear lens aftermarket headlight housings. The clear lens makes any of the defluting process explained here unnecessary.

  7. With the reflector housing prepared, the next step is to mount the projector. There are three commonly used ways to mount a projector to a housing:
    • Threaded shaft: Easiest mounting method. Not possible in GMT400 housings because of shallow housing depth
    • Nut-and-bolt: Good method to use because allows easy adjustments of projector. Possible on GMT400 housings. Unfortunately I did not know about this method at the time. I used this method on my high-end build described later. Now that I
    • Build a bracket: This was method I brainstormed for my first retrofit described here. Basically I made a bracket out of aluminum sheeting, cut a hole to fit the projector through the sheet and drilled some holes to mount the projector to the aluminum bracket. Then when the projector was secured to the bracket, I epoxied the aluminum bracket with attached projector to the back of the housing. Although I describe this method that I used on my budget build in this post, I recommend using the nut-and-bolt method for retrofitting projectors into the GMT400 headlight housings. It is cleaner, more simple to accomplish, and allows easy adjustments. I simply did not know about that method when I was building this budget build. Lightwerkz video that does a great job explaining the different projector mounting methods.

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      Aluminum bracket made for mounting projector in foreground. In background is OEM housing with much of the back of the housing removed in order to make room for the projector.

  8. When mounting the aluminum bracket to the back of the reflector housing, it is critically important that the platform provided by the bracket be perpendicular to the direction the projector needs to be facing. Small variations can be made by adjusting the way the projector is bolted to the bracket, but if the bracket is grossly off alignment, the projector will be too. This is difficult to describe, but use the reference lines that were described in step 3 to aid in generating a surface that is flat and perpendicular to the front/back reference line. I used a grinder to help generate the flat surface needed. The goal here is to have the newly bracketed projector pointing in about the same direction as the halogen high beam. I tested this by wiring up the partially finished assembly to turn on the projector and the halogen high beam and pointing it at the other end of the garage. Basically what I was looking for was that the hot spot of the high beam was centered at just an inch or so above the center of the cutoff from the projector. This confirms that when the assembly is finally installed on the car, the high and low beams will all be pointing in the same direction, with the halogen high beam aimed slightly higher than the projector low beam. It also ensures that the housing can be installed on the car without having to make a massive amount of adjustment to aim the projector. If this step is not taken, the halogen high beam will likely become useless because because its aim point is so much different than the projector low beam. It also may result in a headlight that needs to be adjusted so severely that it bulges out from the grill in an attempt to align the projector. The aiming of the projector output relative to the high beam is critical. Use the high beam and low beam on at the same time to align the projector in the correct orientation before any permanent adhesive is applied

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    Aluminum bracket mounted in place to the back of the projector using permanent adhesive.


  9. When the surface for the bracket is ready and the projector is pretty well aimed, I used an epoxy to permanently adhere the metal bracket to the back of the reflector housing. Here another aspect is important to properly align everything - the rotation. The rotation of the projector must be in alignment with the housing otherwise when everything is finally put back together you will end up with a cutoff that is not parallel to the ground. The alignment is pretty easy to lock down because the GMT400 headlight housings are nice and rectangular in shape. I took extra care to make sure a horizontal line generated by following the top of the projector housing was parallel to the top of the headlight housing. When I had that rotation locked in where I needed it, I finally epoxied the bracket permanently in place to the back of the headlight housing. I made sure to use coarse sandpaper to roughen up the side of the bracket being epoxied to make for a better hold as well. I used a JB Weld epoxy, but the faster JB Quick variant can also be used. I held the assembly in place until I was certain the epoxy was holding firm in order to make sure that the delicate rotation adjustment of the projector did not move out of place. I let the epoxy sit overnight to ensure good permanent adhesion.

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    Projector mounted to the bracket and bracket mounted to the housing.


  10. Finally, the projector, bracket, and housing are all in one piece. I then plugged everything back in to double check the alignment of the projector, both up/down left/right and rotational. If I found a slight adjustment was necessary I used washers to slightly change the distance between the projector and the bracket until I had it exactly where I wanted it. If you did a careful job in step 8, there should only be minimal adjustments necessary here. Make sure you get all the adjustments done in these steps because once everything is put back together it becomes infinitely harder to make changes.

  11. Weatherproofing the assembly is the next step. Thankfully, in this budget build with the smaller H1 mini projector, much of the projector is already firmly inside the housing. I just confirmed that there were no gaps in the epoxy between the aluminum bracket and the back of the housing, and then used a bit more epoxy to fill the very small gap between the bracket and the projector that was caused from adding a couple washers during the adjustments. The bottom of the projector containing the solenoid for the bi-xenon shutter mechanism was still slightly exposed and I was concerned about breathability of the housing when I was complete - a big problem when people start cutting open their headlights is condensation becomes an issue. So I epoxied all the way around the projector but intentionally left a small gap open to allow movement of air in/out of the housing. I then used a small bit of light foam wedged in the gap to prevent dust from moving that same gap. I also made sure that this small gap and a bit of foam was not in a location that would be getting wet during driving in heavy rain or car washes. Hard to describe, but something that is necessary to think about to prevent condensation/dust/water issues.

  12. Everything should be coming together now. Test the solenoid for the bi-xenon function to make sure it works, should hear an audible click when power is applied to it from the shield dropping down out of the way to provide the high beam effect. Then the next step is to prepare the vehicle to make room for the additional space being taken up by the projector.

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    Headlight housing re-assembled with projector and ready for install on vehicle.


  13. The back of the headlight mounting hardware also needs to have material cut away to make room for the projector. This was easily accomplished using the same hole saw mentioned in step 5 and then making small pieces as needed with a dremel. Make sure there is a little room between where the projector is sticking out and the headlight mounting hardware to allow for the slight adjustments that will be necessary during aiming. Also in my case, the projector was bumping into the side of the hole in the radiator support where the headlight wiring comes through, so I used the dremel to slightly grind away some of the metal in that support to give room for the projector. Thankfully there is a lot of room behind the headlights to give room for the additional depth of the projector, so once the headlight mounting hardware is modified and if necessary slightly modifying the radiator support, there is plenty of room to work with.

  14. Install the new headlights on back on the vehicle. They will not be aimed properly, if you took care to align everything correctly in steps 8,9,10 they should be ballpark close. The rotation of the cutoff should also be parallel to the ground. If that isn't you are in rough shape because the headlight adjustments will not fix the rotation. The headlight adjustments will only be able to provide up/down left/right adjustment of the projector. Use the proper tools to adjust the projector output, on OEM headlamps a torx bit is necessary to make the adjustments while on aftermarket headlamps the adjusters are often simply Phillips head screwdriver. The rule of thumb for projector cutoff is that it should be about 2 to 2.5 inches below the headlight height when the vehicle is 25 feet from the wall. Make adjustments and then test out to make sure the cutoffs are below vehicle mirrors when a reasonable distance away. Want to strike a good balance between allowing good visiblility, but making sure projectors are pointed in a direction towards the ground. If aimed too high the hot spot generated by the projector just below the cutoff is not doing any good because it shoots off to infinity instead of hitting the ground, and if aimed too low the purpose of increasing visibility by doing the retrofit is negated.
 
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GMT400Tahoe

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Retrofit 1, a budget-minded retrofit (continued):

Results:
Even at a total cost of less than $200.00 for all parts needed for this retrofit, the lighting improvement provided by the retrofit was dramatic.

The projector provides a nice even light output all the way out to the cutoff, allowing better distance visibility while still in low beam modes. I spend a lot of time driving on Wyoming highways at night and the increased light output allowed me to see much farther down the road to better scan for animals in the road and buy me more reaction time to respond to danger.

In addition, when the bi-xenon high beams are activated, visibility increases to distances such that I can scan the same distances ahead of me that I do when it is daylight.

Finally, lighting width is also improved by the retrofit, allowing more visibility of potential dangers off of the shoulder of the road.


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Budget build, xenon low beam only. Notice cutoff provided by projectors so that light is directed fully at road, not scattered in all directions. Also notice functional white light provided by 4500K bulbs.



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Budget build, bi-xenon high beam and halogen high beam illuminated. This setup provides such great illumination that long distance visibility is nearly that of daylight conditions. Only drawback is that bi-xenon high beam illuminates road signs with such brilliance that the reflections back can be blinding. Thankfully, lighting is often good enough in with low beam only that the bi-xenon feature is rarely needed even at highway speeds.


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Budget build, GIF file showing direct comparison between low beam and high beam settings.


Since this retrofit was my first attempt, it is not perfect, and there were a few issues I wanted to improve upon for my next build. My biggest criticisms of the budget build are as follows:
  • H1 bulb alignment issues. The two most commonly discussed bulbs in projector retrofitting are the H1 bulb and the D2S bulb. The H1 bulb is used in these projectors, and is known for having finicky alignment issues requiring the bulb to be placed in the projector at just the right placement in order to provide the best hot spot and cutoff characteristics. Also the bulb holder on the H1 projectors is a small metallic clip that allows the bulb to rotate a few degrees within the projector, which further attributes to the finicky alignment issues. This is attributed to the H1 being aftermarket bulb, so not as good of quality control as OEM bulbs. In contrast, nearly all OEM HID lightning uses the D2S bulb, which does not suffer from the same bulb alignment issues as the H1 bulb.
  • Crispness of cutoff less than perfect in defluted lenses. One of the desirable characteristics of a projector retrofit is the sharp, crisp cutoff provided by the projector. While the Mini H1 projectors I purchased indeed provide that cutoff, the crisp lines are blurred after they are placed behind the lenses on my vehicle. Even though I made an effort to deflute the region in front of the projector, I hypothesize that the because this was done by hand it is not perfectly flat and could be diminishing the sharpness of the cutoff. While the cutoff is still visible, it is not the perfectly crisp line that is desired. Therefore this is purely an aesthetic issue and does not effect the overall functionality of the retrofit.
  • Light intensity still outperformed by OEM systems. Even though the lighting provided by the retrofit is much better than the output of the halogen reflectors through the stock vehicle wiring, the output is still less impressive than the OEM output on high-end vehicles. This is a result of the budget nature of this build, where the least expensive components were used. The D2S bulbs mentioned earlier that are used in OEM systems are known for producing more light output than the H1 bulbs, and OEM ballasts are also known for contributing to better light output.

Given these criticisms, the budget build still leaves room for improvement. I would consider the budget build to be a very effective functional projector retrofit, but lacks some of the flashier benefits provided by other retrofits.

This is ultimately what inspired me to make another retrofit that I call the high-end build. In this build I wanted to address the previously mentioned shortcomings by using one of the best D2S bulbs on the market, a very well reviewed projector, OEM ballasts, and clear glass headlight lenses. The high end build is expected to retain all of the functional improvements of the budget build but also benefit from the other desired characteristics of a projector retrofit. As of 09/16/2017 the high-end build is still a work in progress, and results will be shown in following posts.
 
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GMT400Tahoe

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Retrofit 2, a high-end retrofit:
The second retrofit I completed was a high-end build using knowledge gained from the first retrofit in order to produce the highest quality lighting possible. It was also successful and provided further lighting improvement for my vehicle. I did a better job documenting my work on this retrofit than I did on the previous one, trying to take as many pictures of the process as possible to guide any others that may be interested.


Parts:
  1. Recycled Parts: I recycled some of the parts from the budget build to use in the high-end build. The recycled parts that I had on hand were as follows:
    • HD wire harness ($25.00)
    • High beam splitters ($5.00)
    • Capacitor ($15.00)

      See parts description in Post #2 of this thread for description of what these parts are necessary for. Also recall that the 4-hi mod is also a necessary requirement on these vehicles in order for the bi-xenon function to work.


  2. Morimoto FX-R 3.0 bi-xenon projector, 2.5 inch lens: These are widely accepted as one of the best overall projectors on the market. Notice the 2.5 inch lens size, which is important to note because there is also a 3 inch lens option. The 3 inch lens will be too tall to fit in the GMT400 headlight housing without severely cutting the top and bottom of the housing, which will make weatherproofing steps later on nearly impossible. I strongly advise against purchasing any projectors with 3 inch lenses for our vehicles because they will be too tall for the GMT400 headlight housing. The bulb type used in these projectors is the D2S bulb, which is a common OEM bulb type. ($110.00)
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  3. Osram 66250 CBI bulbs: These are widely accepted among retrofitters as some of the best HID bulbs you can buy. The produce some of the greatest magnitude light output and produce light at a cool white color of 5500K. These bulbs produce a slightly whiter light than the 4500K bulbs I used in my budget build, which usually corresponds to a decrease in output intensity, but since the CBI is such a high-end bulb the intensity is expected to be much greater. Basically, the Osram CBI bulb is able to produce a desirable cool white color output while not sacrificing light intensity ($110.00/pair)
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  4. Hella ballasts, gen3 (5DV 007 760) ballasts: These are Hella manufactured 35 Watt ballasts that I purchased used by pulling them myself from a vehicle in a salvage yard. I specifically pulled them from W210 Mercedes-Benz E-class. I used these ballasts because OEM ballasts are generally considered to yield the best performance and reliability, and the Hella generation 3 was a ballast I was already familiar with from one of my other vehicles. One of the nice perks of pulling this part from the W210 E-class was that the ballast came with a nice cradle for the ballast that I was also able to use in my build. These particular ballasts types are not necessary for a retrofit, but I used them as a personal preference. So if you do not want to scavenge parts from a salvage yard, there are many quality ballasts available at The Retrofit Source or Lightwerkz. I paid $24.00 for the pair of Hella ballasts at the salvage yard - a smoking deal.
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  5. E55-R shrouds: The shroud is simply a piece of plastic that covers the face of the projector to provide a finished look to the product. Notice I did not use a shroud in my budget build because I left the fluting in all regions of the headlight except the part in front of the projector lens, so a shroud was not necessary. A second benefit of a shroud is that it catches light bleed that occurs out the sides of the projector, which on a projector retrofit could still hit the sides of the reflector and inadvertently cause glare. Although notice that the FX-R projector being used in the high-end build is completely enclosed, so light bleed will not be an issue in this build anyway. The shroud is simply being used for aesthetic purposes, and I like the clean appearance of the E55 shroud. Once again, the shroud used, or the decision to use a shroud at all, is a personal preference and does not affect the performance of the retrofit. Most projector shrouds are made for 3 inch lenses, and recall for the GMT400, a 2.5 inch lens must be used, so if a shroud is to be used, be sure to also include the appropriate shroud centric rings which are used to snugly fit the shroud on to the smaller lens. If the projector and shroud is purchased from The Retrofit Source, they will include the appropriate shroud centric rings at no additional cost. ($30.00)
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  6. Spyder Auto aftermarket headlamp housings, clear glass lens: I purchased these aftermarket headlamp housings for three reasons:
    • They have a clear lens that requires no defluting and which will not distort the projector output
    • The lens is glass, so will not oxidize over time and become dull like the plastic OEM lenses.
    • The headlight lens is attached to the reflector housing using a butyl sealant which can be heated using a heat gun or oven to allow the sealant to release in order to more easily perform the work necessary for the projector retrofit.

      I purchased the headlamp lenses from Amazon. Amazon link for Spyder Auto headlamps purchased. The cost for the headlamps with shipping and tax included was $111.17

Notice that the total cost for everything I needed for the high-end build was $385.17 in new parts, plus the $45.00 worth of parts I recycled from the budget build. Therefore the total cost for the high-end build sums to $430.17. But recall that I got a great deal on the Hella ballasts by pulling them from a vehicle myself at the salvage yard. If I had not saved that money on the ballasts, I expect the high-end build to have cost approximately $475.00 or so in parts. Notice the high-end build was more than twice the cost of the budget build, which came in at only $190.00 in parts and used OEM headlight housings that I had on hand.
 
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GMT400Tahoe

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Retrofit 2, a high-end retrofit (continued):

Installation:
The following are the steps I took during the building of my second GMT400 retrofit. I learned from some of the mistakes and shortcomings of my first GMT400 retrofit to improve this one, but it is still not perfect. As before, please use these steps as a general guide, but not a definitive step-by-step instructions for performing your own retrofit.

Before starting, note that the high-end retrofit uses a projector that is larger (more depth) than the projector used in the budget build, and therefore the projector extends farther behind the headlights. Therefore the high-end build using the FX-R 3.0 projector required cutting and removing small portions of the the steel radiator support in order to allow the projector to fit. Do not proceed if not prepared to cut the steel radiator support.

  1. Start with the aftermarket clear lens headlamps by disassembling the reflector housing from the two black plastic mounting brackets. The flat bracket that mounts to the radiator support is easily removed, but the other portion of the bracket that clips into the reflector is more difficult to remove. Be careful not to break these small plastic clips that attach the headlight bracket and adjusters to the back of the reflector. I used a set of plastic interior panel removal tools to help remove this clips without breaking them. For stubborn ones, I used a heat gun to heat up the plastic and make it more pliable to help with removal without breaking the plastic. Like before, be especially careful with these adjusters, because they are fragile and essential for the aiming of the finished headlight.
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  2. Once the reflector and lens portion of the headlight assembly is removed from the plastic brackets, remove the lens from the back of the reflector housing. This can be accomplished in one of two ways:
      • Use a heat gun to apply heat directly to the portion of the housing where lens attaches, working around the housing until complete.
      • Use an oven to apply heat to the entire housing, then remove from oven and pry housing apart before it cools.


    I used a heat gun during my work since it is easier to direct where I want the heat as I pry the housing apart. If an oven is used, a temperature of 270 F for approx. 7 minutes is recommended. You only want it hot enough to heat up the butyl sealant, but not melt the plastic housing.

    When using the heat gun, I applied heat all around the border of the headlight to heat up the butyl sealant, then I focused the heat to one side of the housing and used the same interior panel removal tools to gently wedge in the space between the glass lens and the housing and then wedge them apart. Be careful not to damage the housing during this prying of the lens from the housing. As the butyl sealant begins to let go, pry the lens from the housing and work your way around the housing, applying heat as needed. Try to prevent the sealant from dripping on to the lens or on to the reflector housing during this removal process - it is a pain to try to get off.
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  3. Place the lens somewhere clean and safe, will not need it until finishing the retrofit. The reflector housing needs to have enough material removed in order to fit the projector. To do this, first use a sharpie to mark on the back of the reflector reference lines directly vertical and horizontal of where the low beam bulb fits. These reference marks are helpful later on when making sure you are placing the projector in the correct location on the back of the housing. Once reference marks are drawn, use a 3 inch hole saw to remove much of the back of the reflector. Be careful that the hole is centered over the hole where the low beam bulb used to go, although it doesn't have to be absolutely perfectly center, because more material will have to be removed after the 3 inch hole is drilled. The 3 inch hole just provides a good amount of starting material to remove. After the 3 inch hole is drilled, you will be able to fit the face of the projector into the hole to get an idea of the amount of additional material that will need to be removed. From here I simply used a sharpie to guide further cuts using a dremel, with the goal being to make room to fit as much of the projector forward in the housing, without extending too so that the lens of the projector would go past the glass lens of the housing. Use your judgement on this, it's hard to describe. But remember that removed material cannot be put back, and you do not want large gaps between the projector and the housing either, so slowly remove material and try not to remove more than necessary. The shape that I ended up with is shown in the following picture.
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  4. Now that there is room for the projector to fit through the housing, need to mount the projector. Here I used what is commonly called the nut-and-bolt method. Watch this video provided by Lightwerkz for a great explanation of this method, much better than I can do. Lightwerkz nut-and-bolt method video. Unfotunately, the GMT400 headlight housings are too shallow to bring in the FX-R projector from the front like they show in the video - the face of the FX-R projector would extend past the headlight housing lens if we did it that way. Perhaps a smaller projector like the Morimoto Mini H1 could work the way as shown in the video, but recall I wanted to use the best components in this high-end build, so I am using the larger FX-R projector. So for the GMT400 we need to bring in the projector from the back of the housing and bolt it to the reflector from the back instead of from the front as shown in the Lightwerkz video. NOT FINISHED WITH THIS THOUGHT. LEFT OFF HERE.
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GMT400Tahoe

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Results: (thread not finished, just preview here)

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Close-up view of the high-end build installed. Compare to close-up view of budget build shown in post 1 of this thread. The high-end build has a bit more of a custom look to it, compared to the OEM+ appearance of the budget build. Really, I prefer the OEM+ appearance of the budget build, but the performance of the high-end build can't be beat. So ultimately the second retrofit represent bit of a trade-off for me.


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Preview of finished product. Gif file showing:
  1. DRL
  2. off
  3. parking lamp only
  4. xenon low beam
  5. bi-xenon high beam in conjunction with halogen high beam
  6. xenon low beam
  7. parking lamp only
  8. off

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High-end retrofit results. Rocky Mountain National Park.

 
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