# Mk4 Golf LED Retrofit



## liseed (Apr 3, 2012)

MK4 Golf quality LED bulb retrofit.

I had to fabricate and machine some parts to allow for the larger LED bulbs to fit. I used aluminum and incorporated heat sinks into my design to help keep things cool (most likely not really necessary since LED bulbs run cooler that stock halogen bulbs, but it cant hurt!). This set up is easily 2 or 3 times the output of regular halogen bulbs + all the benefits of LED lighting! This set up should be future proof as well, allowing to simply upgrade the bulbs as better ones come out, assuming the footprint of future bulbs stays roughly the same.



Headlight housing modified as required for LED bulbs:




















High-beam side required a custom spacer to allow for the larger bulb and eliminate interference with the existing wiring:



















Low-beam side and fogs required custom caps to allow for the larger bulbs and allow some airflow behind the bulbs. The bulbs do fit without modifying the cover, BUT the bulbs are right up against the cover and would most likely overheat due to fan airflow being blocked. I also incorporated a heat-sink to help cool things off.





































foglight cap installed:
Foglight cap was challanging to machine because of the uneven surface of the headlight bulb cover behind the foglight bulb. It has 3 different surfaces, and one of them is curved!










If anyone is interested, I can fabricate these parts and/or modify your existing headlights.


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## liseed (Apr 3, 2012)

*Stock vs LED*

Left side of the car stock halogens vs right side of the car LED.

Ill post more on dark road after I finish the left side housing.


High beams: incredible difference!


















Low Beams: wow!









Fogs: definitely a lot brighter, AND has the option of toggling from yellow to white just by turning fog lights on/off again! 
I often use fogs to light up the sides of the road in deer country. Use of fogs has saved me from deer a few times just because I was able to spot them sooner.


Yellow:









White: (all I did was turn fogs off then on again to get the LED side to change to white).


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## liseed (Apr 3, 2012)

I had to redesign the left side heat-sink caps to accommodate the plastic air intake cover between the battery and the headlight assembly. (I had to shorten the stick out 1/3 of an inch or so from my original design). The heat-sinks work great! They are noticeably warmer than the surrounding headlight assembly during operation. They also accommodate the many different bulbs I have been trying out. No condensation, as I was careful to seal everything and use the original seals on both bulb covers.


LOWBEAMS: I have tried 3000, 4000, and 5000 lumen bulbs behind the stock celis low beam projector. I settled on the 5000 lumen bulbs. 5000 lumen bulbs about match the stock halogen bulbs in terms of wattage, but they are a little over 3 times as bright in terms of lumen output! At the 5000 lumen output, I find they seem to about match the brightness of modern LED headlight systems (just by eyeball comparisons) and yet have a nice crisp cutoff line just as they did with stock halogen bulbs without glaring oncoming traffic. I have even noticed a few LED headlights in new cars that were even brighter than this, but I did not want to exceed the wattage of the stock halogen bulbs, as there are possible wiring harness issues if you exceed the wattage the car was designed for. The 3000 and 4000 lumen bulbs were still fantastic improvements, however.

HIGHBEAMS: I tried 3000, 4000, and 5000 lumen bulbs in the stock celis reflector style high beams. I settled on 3000 lumens. 3000 lumens is about 2x the brightness of stock halogen bulbs, but it sure seems like more. Bright but not dangerously bright, IMO. I can drive at 100 mph and not over-drive my headlights with these, easily. Really makes a difference on dark country roads! I can see deer I was not able to see before because the sides of the road are lit up MUCH better than before.

5000k lumens is definitely off road only! (I really mean it, lol). Turns night into a bright day!
4000k lumens was just a tad too bright also, (it only turns night into a normal day) as when I dipped to low beams after using these for a while, it was actually a bit blinding, kind of like when you take dark sunglasses off on a bright day, it took a minute or two to readjust, even with the brighter low beams, and I found that to be dangerous, especially when there was oncoming traffic headlights added into this effect.

FOGLIGHTS: Mine are flip chips, which means they flip from yellow to white light just by turning them off and on again. I absolutely LOVE this!! Again, I LOVE this! Mine output 3800 lumens. They seem put out about as much light (maybe a tad dimmer) as the low beams on the road. The fogs don't have a projector like the low beams, just a glass lens with a metal cutoff. Like the low beams, these also have a crisp cut off line without glare above the line. The cutoff line just about matches the low beam cutoff line on mine. They are bright enough to use just by themselves, even at night. The yellow light really makes a difference in inclement weather, it really adds to contrast (just like wearing amber lenses in your ski goggles). I often run the foglights on white with the low beams as this lights up the sides of the road in rural areas even better than low beams alone.

ALSO: edited the op to include a pic of the completed mod with the fog light heatsink cap.


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## ShavedRabbit (Sep 6, 2002)

Can i ask why you put all that work in just for drop in led bulbs? instead of using a good/proper led projector?


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## 3L3M3NT (Jun 18, 2008)

How have the headlights been performing this winter? If you could post up some additional pics that would be fantastic!:thumbup:

I'm trying to figure out what I wanna do with my MKIV Golf headlights and this definitely has me intrigued especially if they fit behind air intake cover on the driver's side headlight. If you could pm me an estimate of what it would cost to have you make me a set of LED headlights out of a set I have would be very helpful.


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