Honda Prelude (4th Gen) Projector Headlight Retrofit
Introduction
This guide covers converting the sealed reflector headlights on a fourth-generation Honda Prelude to a projector setup, so the car throws a sharp, level cutoff and far better night-time light than the factory optics. The method opens the headlight, mounts a small projector (Acura TSX clear-lens optics are the common choice, with BMW E46, Honda S2000, and Lexus RX330 projectors as alternatives), dresses it with a shroud, and reseals the assembly for an HID kit. The same approach applies to both the JDM one-piece lens and the USDM housings, and it typically costs a few hundred dollars less than buying finished retrofit lights. Plan on fabrication: you will trim the reflector and interior plastics, build or adapt a shroud, and dial in the aim by hand. Adapted from a community writeup by n0rmaL on PreludePower (https://www.preludepower.com/threads/official-retrofit-picture-thread.325818/), including corrections from the follow-up discussion.
Reference
Tools Required
- Oven
- Baking tray and a towel
- Flathead screwdriver
- Phillips screwdriver
- Rotary/cutting tool for trimming plastic (e.g. Dremel)
- Marker for alignment reference
Parts Required
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Projectors - Acura TSX clear-lens units are the easiest to source (2.5" lens); S2000, Lexus RX330, or BMW E46 bi-xenon optics also work
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Clear projector lenses in place of the fresnel type
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HID kit: D2S bulbs (e.g. 4k), a bulb holder/adapter, and a ballast
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Shrouds/bezels - BMW E46 bezels, or a 3"-4" ABS duct reducer plus a travel-mug chrome ring for a home-built shroud
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Mounting hardware: 1" L brackets, #8 32x5/8" bolts, nylon lock nuts, and flat plus lock washers; one 1 1/2" bolt for the upper mount
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High-temperature epoxy rated to roughly 500 degrees
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Aluminum/foil tape for sealing the rear
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JB Weld (optional, for additional bond strength)
Safety Warnings
- ⚠ Lock every fastener with nylon lock nuts and lock washers; a projector that works loose while driving can shift the beam or fail.
- ⚠ The headlight is hot straight out of the oven - handle it with care and let it cool before heavy handling.
- ⚠ Do not overheat the housing; use 350 degrees to open and 300 degrees to reseal, both for about 8 minutes, to avoid warping the lens.
- ⚠ Improperly aimed HID beams dazzle other drivers - always set the cutoff low and level before regular use.
Step-by-Step Instructions
1 Gather projectors, lenses, and HID components
Choose a compact projector with a clean cutoff. Acura TSX units are recommended because they are inexpensive, easy to find, and reasonably small; their lens measures 2.5" across. If the projectors ship with fresnel lenses, order clear lenses separately, since the clear glass gives noticeably better output. Also collect the HID hardware you will run inside the finished housing: D2S bulbs (a 4k color temperature is a common pick), a matching bulb holder and adapter, and a ballast.
2 Open the headlight in the oven
Preheat the oven to 350 degrees. Take out the five metal retaining clips, pull the bulbs and rubber dust caps, and unscrew the two internal brackets (two screws each). Rest the headlight on a baking tray padded with a towel. Switch the oven off, put the housing in, and leave it about 8 minutes to soften the butyl seal. Working slowly, walk a flathead screwdriver around the full perimeter, easing the lens away from the housing a little at a time until it separates cleanly.
3 Trim the reflector and interior plastics
Open up the reflector around the factory bulb hole so the projector can sit where the stock bulb pointed. Cut slightly less than you think you need on the first pass; you can always enlarge the opening, but you cannot put material back, and a conservative cut keeps the projector aimed close to the original direction. Remove the two screws holding the black interior plastic piece on the lens and trim it as required to clear both the projector body and the shroud. Finally, relieve the back of the housing where the bulb clip sits so nothing binds or rubs.
4 Mount the projector securely
Fasten the projector with 1" L brackets and #8 32x5/8" bolts. Bolt only one side at first so you can rough in the cutoff and swivel the unit before committing the rest. Keep the projector level relative to the lens; the housing's own adjusters handle final aim once the car is assembled. Add a third bolt at the top (a 1 1/2" bolt works well) so the projector cannot rotate or drift. Use nylon lock nuts and lock washers throughout to keep everything from loosening on the road, and add JB Weld behind the projector and reflector bowl if you want extra rigidity.
5 Fit and bond the shroud, then seal the rear
Dress the front of the projector with a shroud. BMW E46 bezels are a popular ready-made option, though you will usually need to trim their top and bottom to clear the housing; alternatively, build one from a 3"-4" ABS duct reducer capped with the chrome ring off a travel mug. Run a bead of high-temperature epoxy (rated to about 500 degrees) inside the shroud, press it onto the projector, and hold it steady roughly 10 minutes until it sets hard. Cover any exposed openings at the back of the assembly with aluminum foil tape, which seals reliably and holds up to the heat.
6 Reseal the headlight
Clean both mating surfaces thoroughly. Warm the housing again, this time at 300 degrees for 8 minutes, to reflow the seal, then press the lens firmly back onto the housing. Reinstall the original metal clips right away; they clamp the two halves together while the sealant cools and cures, which makes a much tidier, leak-free bond.
7 Install on the car and aim the beams
Refit the headlights and wire in the HID ballasts. To aim, park about 20-25ft from a flat wall, level the two cutoffs so they match each other, then drive and observe. Return and fine-tune until the beams sit where you want them, keeping them on the low side so you do not blind oncoming drivers. If a light stays aimed too high and the adjusters run out of travel, tighten the lower housing screws while loosening the upper ones, and add small springs to hold the tension; with the L-bracket mount, gently bending the brackets also nudges the projector into place.
Pro Tips
- 💡 Clear-lens TSX projectors are the friendliest to mount; S2000 and BMW E46 bi-xenon are solid alternatives, while RX330 optics are similar to TSX but harder to fit.
- 💡 When cutting the reflector, remove less than you estimate on the first pass and re-check the fit; you can always enlarge the hole.
- 💡 Aim on the low side as a courtesy to oncoming traffic, then confirm on a real drive rather than only against a wall.
- 💡 Aluminum foil tape has proven durable for sealing the exposed rear of the housing.
- 💡 Doing the work yourself typically saves about $200-300 compared with buying finished retrofit headlights.
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