BMW 335d NHK V Bi-LED Retrofit

Living in a rural area with lots short days in the winter, bright headlights are a necessity for comfortable driving. My 2011 BMW 335d headlights came with factory adaptive bi-xenons, but they'd become fairly dim over the past few years. 2 years ago I refinished the hazy outer plastic housing with a 2 stage clear coat and replaced the bulbs with fresh Phillips D1S, but the lighting still wasn't great.

I figured the projector bowls were burned out from 14 years of use, but as I dove further into the OEM BMW modules I learned they were also sort of a poor design. BMW's AFS system on the 3 series moves the headlights vertically and horizontally as you turn the steering wheel to improve lighting around corners, but it does so by shifting the headlight lens in relation to the projector bowl rather than shifting the entire projector assembly, at least in the horizontal direction. Optically, this is far from optimal.

The solution was a full blown projector retrofit, replacing the OEM units with higher performance aftermarket projectors. I found these awesome ZKW AFS to standard G5 projector mounting brackets from lightwerkz. These allow you to mount a G5 pattern projector to the existing AFS brackets, retaining full motion vertically and horizontally. Even better than that, the entire projector assembly pivots with these brackets, so the lens to bowl distance is fixed, eliminating the OEM design flaw.

I've been a headlight enthusiast since high school and have installed various grades of pure chinesium to slightly nicer morimoto bi xenon projectors in the past. This time around Bi-LED units had become more affordable and competitive with the best HID projectors. At the time I was shopping, black friday of 2023, Morimoto and NHK made the best units in the game. NHK had two units available, the NHK IV and V. The V had slightly better low beam performance, but the NHK IV had better high beam performance thanks to a second supplementary led chip for the high beam. On my X5, I have a Diode Dynamics 18" driving pattern light bar for auxiliary high beams, but I had no such plans on the car so I ordered the IV for its superior high beam output (it was a little cheaper than the V too). Both of these units have since been superseded by the NHK M5.

As we moved 1000 miles, these ended sitting on a shelf for a year before I finally recently got around to installing them. I opened the box to find I'd actually been shipped an NHK V pair.

The first order of business was to pull the headlights from the car. I followed this video, pulling the bumper and removing the entire headlight assembly.

With the headlights out, it was time to open up the covers. This era BMW uses permaseal to seal the lens to the housing, which is extremely difficult to remove even with heat. Rather than spend hours with a heat gun or baking the fixtures in the oven like I had on retrofits in the past, I opted to cut around the perimeter of the headlight with a dremel. I read an ultrasonic cutter would be a better tool but the dremel worked fine and didn't make too much of a mess.

With the lens off, I could finally get to work. I removed the chrome shrouds, angel eyes, and plastic surround trim, exposing the OEM projector and AFS system.

I pulled the ZKW units off their mount and installed the lightwerkz bracket in its place, then mounted the NHK V to the new bracket. This all went on very straightforward. On one of the two headlights, the square plastic peg on the top right of the bracket in the below photo was loose in the bracket so I ended up using a little bit of JB Weld to ensure it would stay in place.

With the shrouds off and all the wiring exposed, I took the units back outside, plugged them into the car, and probed with a multimeter for the high beam signal and switched +12V to the OEM HID ballasts. I cut the wiring inside the headlight housing that goes between the main plug on the back of the headlight and the ballast and rerouted it over to the 12V supply for the NHKs. I repeated this for the high beam signal, tying to the new projector solenoid wires. I left the now electrically disconnected OEM ballasts mounted to the outside of the headlight for a clean, original look. From the outside, nothing changed from a wiring perspective.

With the new projectors installed and the wiring complete, I took the open units back out to the car and plugged them in - everything worked as intended. The shrouds didn't mount on to the new projectors so I ground off their original mounting posts and affixed them with epoxy to the new NHK projectors. Some of the chrome flaked off while I was handling the shrouds (this stuff is extremely sensitive - use gloves!) so I scuffed them with sandpaper and hit them with some high temp black paint. I think the black look looks a little cleaner anyway.

Next, I had to reattach the headlight lens to the housings. I used an old soldering iron to plastic weld them back in place, first tacking a few spots to hold everything in place and then going around the entire housing.

To ensure a watertight seal, I covered the plastic welded areas with a bead of permatex 81173 adhesive sealant.

I reinstalled the units in the car - with the hood closed, none of the cut/repaired area of the lens could be seen.

Finally, some output shots! I rough aimed the headlights and took them for a test drive. They were orders of magnitude better than the OEM units and much to my surprise, the high beams, despite missing the supplemental LED of the NHK IV, were unbelievably good too. Lights stayed bright throughout corners.

Despite the high time commitment, this was one of my favorite upgrades to the 335d.