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De-Chroming & Modifying Headlights - The Definitive Guide

moonstone

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INTRODUCTION
Although there are a handful of companies out there that offer headlight modification services, they generally charge anything up to £2000 and you need to send your headlights in. In truth this is a tricky DIY but can be done with time and care. There is a lack of information online on how to do this. I've done it a couple of times now and thought I'd share what I've learned and how to do this for yourself. In my opinion this is not something that you should do on your existing headlights if your car is a daily driver. You need time to do this properly, allow paint to dry and de-gas etc. In my view it's better to buy a second set of headlights, mod them and then swap them over. You can then sell your old ones and recoup the cost of the new ones (or even mod the second set and sell them on at a profit). Please note, all photos are thumbnails. If you need to see them bigger just click for the full image.

Removing headlights
Generally on any modern car, removing the headlights means taking the front wheels and front bumper cover off. This seems daunting but it isn't really. It's just time consuming. On almost every car I've worked on it's gone the same way. Wheels off, arch liners disconnected at the front and then a series of screws under the bonnet and under the front end of the car. Bumper then just clips off. There's lots of resources on the web on how to do this so I won't cover it here (particularly when it various from model to model).

Headlight Structure
Again, on modern cars, Headlights tend to be made the same way in the factory. The main housing has a female "gutter" that runs along the front which is then filled with hot Butyl rubber glue before the rear edge of the lens is inserted. Whilst the rubber is still hot the lens is either clipped or screwed into place. Butyl rubber cannot be removed using chemical solvents. It can only be removed mechanically. Much like Sikaflex and Betalink on car bodywork.

Opening the headlight
So how do you split it open then? There are a few methods, all involving heat. If your headlight is small enough, you can stick it in your oven for ten minutes at around 100 degrees C to soften the Butyl rubber. You then get a pick and try to remove as much of the rubber as possible from the gutter to enable you to split the headlight. I used this method with my M4. There are dangers that you can melt part of the lens if it touches any of the walls whilst heating. If you can't fit your headlight into the oven then you can use a heat gun (readily and cheaply available and the same sort of thing that you'd use to strip gloss paint from household woodwork), just heating a section at time and using your pick in the same way.

Both of the above methods are time consuming, extremely messy, and run the risk of damaging the gutter on the headlight housing. Also, it is almost entirely guaranteed that you will stab yourself multiple times! A better option in my experience is the method that I outline below, but it does require that you purchase new lenses prior to starting the job.

Butyl Rubber Alternatives
Rolls of Butyl Rubber are available but it's hard to work with. I prefer using a tube of Sikaflex or TigerSeal instead. Once set it's pretty much exactly the same.

OVERVIEW
Although in my example I'm using a BMW 5 series headlight, this process is pretty much universal. There are elements mentioned below that are specific to the 5 series / M5 headlight that I'm working on but just ignore these and apply the same principles. In this method, we're going to destroy the existing lenses and replace them, so having a replacement set on-hand is essential. Also, if you're going to all this trouble, it makes sense to have a brand new lens, rather than one that's battered and stone chipped.

Tools and items required:

Tools.jpg
  • A set of picks - https://www.halfords.com/tools/gara.../rolson-4-piece-pick-and-hook-set-340885.html - For removing Buytl Rubber
  • Flat head screwdrivers - Also for removing Butyl
  • Torx screw driver set (various sizes required) - For dismantling decorative elements and healdight internals
  • Heatgun - to heat up Butyl Rubber making the lens material easier to remove
  • Cans of Compressed Air - For getting rid of plastic or rubber particles inside the headlight housing
  • Microfibre clothes and smear free glass cleaner (as above)
  • Oscillating Multi-Tool and plastic cutting blade for cutting the lens
  • New set of lenses - These are readily available online either from ebay or Aliexpress. In both times I've done this, the replacement has been identical to the OEM version on the existing headlight.
  • Pliers - For removing the remnants of the lens material from the headlight housing.
  • Snips - As above.
  • Direct-to-plastic paint such as Plastikote. Get two cans at least.
  • Box of Oven Pride (oven cleaner) for stripping the chrome from plastic.
  • Rubber gloves - The last thing you want is finger prints... anywhere!
  • Clamps - These are optional but come in handy to hold the new lens tight to the housing when the new glue is setting.
METHOD
I'm assuming that you have the headlight removed from from the car already. If you're using your existing headlights, your car is going to be off the road for 2-3 days if you want to do this properly. I did this work over a two week period.

Step 1 - Chopping up the existing lens
Take your multitool and cut around the lens itself, leaving 10-20mm of lens material around the entire outline of the headlight. This allows you access to the internals and on the G30, most of the internal parts that we want to paint are attached to the lens rather than the headlight housing. More importantly, in the next step this allows you to completely remove all of the lens material from the housing-gutter without risking any damage to the housing itself. TAKE CARE NOT TO CUT THROUGH ANY TABS! On the M5 there are two tabs that attach the eyebrow on the lens to the housing. In this car you would then use your pick to separate it from the rubber once you've cut the bulk of the lens away.

Multitool.jpg Lens-tab.jpg Lens-removed.jpg

Step 2 - Removing the remnants of lens material
After removing the cut away lens, you'll be left with around 10-20mm of material all along the edge of the headlight housing. We're now going to remove this using our heat gun and pliers. Pick a suitable place to start andc using your snips, cut into the lens material. At present, it's one continuous piece so we need to cut it so we have a starting point to start to remove it and then work our way along. Using your heat gun at around 200 degrees C (sounds a lot but as long as you keep it moving and don't heat the plastic for too long you'll be fine) heat up a section of the housing edge around 2-3 inches and then use your pliers to pull out the lens material. I found it helpful to twist my pliers round in a circular motion. By doing this all along the edge of the headlight you'll pull out the remnants of the lens and a good bit of the butyl rubber with damaging the housing.

Make sure that you have removed any clips or screws that are used to attach the lens to the headlight housing. On the M4 there were metal clips, on the M5 there are a few screws along the gutter itself.

Lens-pull1.jpg Lens-pull2.jpg


Step 3 - Get rid of the existing butyl rubber
Remove any remnants of the butyl by scraping along the gutter with a flathead. Get out as much as possible so that there are no obstructions to the new lens but don't worry about some bits and pieces hear and there on the edges. If any of the gutter has been bent back then you should re-shape it with a little heat and your pliers.

Butyl-removal.jpg

Step 4 - Dismantle the internals
Now you want to remove any of the decorative elements that you intend to paint. usually this involves a series of Torx screws and clips. Be very careful. If you break something it's going to be a ball-ache to fix and near impossible to replace unless you buy a full headlight and open up another headlight for parts.
 
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moonstone

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Step 5 - De-chrome
Now that you have your parts removed for painting, you want to get rid of the chrome. It is possible to paint directly onto the chrome but there may be some adhesion issues and I prefer stripping it down to the bare plastic. To do this, stick them inside your Oven Pride bag and empty the contents of the bottle. Leave overnight. When you return the chrome will have disappeared entirely or still be present in the bag, but in any case will no longer be on the plastic itself. Remove the plastics from the bag, wash and dry.

Oven-P-Box.jpg Oven-P-Start.jpg OvenP-During.jpg OvenP-Done.jpg

Step 6 - Paint
Painting. There's plenty of guides on the web on how to spray paint so I wont cover it here. All I'll say is be patient, use many light coats rather than rush it and you'll have an OEM look with any decorative patterns on the plastics still being present once your done (as opposed to flooding any textures with paint).

Painted.jpg

Step 7 - Patience!
Don't rush into putting things back together. If you can still smell a strong whiff of paint from the parts, leave them for a day or so for the paint to fully de-gas before putting everything back together.

Step 8 - Cleaning
Now that everything is back together, you want to thoroughly clean everything. Make sure there's no loose bits of rubber or plastic inside the the housing or the lights. Chopping op the old lens with the multi-tool is messy and will result in a lot of plastic in the housing. That's the down-side of this method. Use your can of compressed air to blow out any small particles. use your glass cleaner and microfibre to make sure all of the internals including the lights themselves, inside the lens and everything else is absolutely spotless.

Step 9 - Gluing back together
Take your Sikaflex and lay down a bead inside the entire gutter along the edge of the headlight. Once done, take your lense and press the edge into the gutter, ensuring it's pushed all the way in, all along it. Once in place, re-attach any fixings that hold the lens in place, such as the clips on the F80 or screws on the F90. If your particular headlight doesn't have any fixings that hold it in, you'll want to use your clamps to hold the lens to the housing. Now leave everything alone for 24 hours.

Step 10 - Your done!
Now all you need to do is fit the headlights to your car. If your swapping a set over, then make sure you fit your existing headlight modules to the new headlights before fitting. You should also disconnect your battery just to stop any ECU errors that could pop up. Make sure you test your lights before putting your car back together.

 
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boba fett

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That is a brilliant "How to" @moonstone very well done. I would add that you can save your lenses if they are in good condition, and you can split the lens from the headlight by placing the headlight in the oven on a low heat, which softens the adhesive and you can ease it apart with trim tools. It's a ball ache job!

With all this how to in mind it makes me shudder to think I might attempt it again on my M3 !
 

moonstone

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Oooosh - that's a lovely frontage !

Im so happy with how it looks now. I was really not feeling the front end before this but now I think it looks as good as the rear. Massive job for what your average man in the street won’t even notice in isolation but the contribution to the whole package is top drawer. The eye is drawn to the more aggressive Icons and eyebrow instead of the overall chrome contrast between the whole headlight and dark paint.

I’m like a dog with two dicks!
 
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