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This is something I've wanted to do ever since I got my 928:
When you look at the front of a car with 8" H4 headlights vs. the 7" U.S. version with the required chrome trim ring, there's a huge difference in looks. Apparently there's an even bigger difference in light output. So this is one item that lots of people like to add to their cars, regardless of the market where they were originally sold. Of course, that means they are expensive. Wow... they have gotten SO expensive! Even so, IMHO, it's worth the cost.
I was fortunate enough to jump on a set that another member decided to he wasn't going to use. I believe these are early ones, since they lack the "tell tale" pip on top that later years had. Best of all, they were extremely reasonable! Unfortunately, the reflective inner surface had deteriorated enough that I didn't feel it was worthwhile installing them in that condition.
So I disassembled them, then cooked each in the oven at 300* for about 10 minutes, which was enough to soften the adhesive that bonds the glass lens to the metal bucket.
This is what it looked like inside. I'm not a brain surgeon, but I'm pretty sure the reflectability on this is probably the same as cardboard.
The buckets looked a little rough on the outside too, with corrosion around the lip. One was worse than the other, but I had no idea how bad until I put them in the glassbead cabinet.
It was pitted enough that it needed repairing, both to preserve the reflective surface & to seal the holes that had allowed moisture to seep inside the sealed light.
Luckily, I have a friend who is more skilled than I am at metal work:
I did a lot of research while I waited, and learned that the "experts" on internet forums suggest a variety of ways to refinish headlights, including Rustoleum chrome paint, Krylon metallic paint, powdercoating, tin foil (not joking), or silver foil duct tape.
Chrome seems like it would be the best way to do this, but it's actually not. Chrome is only 63% reflective, according to science...blah blah blah.
Fortunately, I learned that the ideal surface in a headlight bucket is silver (100% reflective), but that it tarnishes quickly. You could clearcoat it, but that wouldn't hold up very well with the temperatures. Powdered aluminum doesn't tarnish as quickly and is almost as reflective (96%). So the best coating is vapor-deposited aluminum, which is an extremely specialized process that only a few places offer. But first, the headlights have to be nickel plated, which costs just the same as having them chromed. But remember, DON'T have them chromed!
They look great in nickel! Part of me is tempted to just seal the glass lenses back on & go! But I'm resisting the temptation & will be sending them to the VDA shop, which is supposed to have a quick turn-around. I'll report on the process & results. And I intend to complete the entire headlight & bucket restoration before it's installed on the car. (Let's see if I can get the headlight adjusters to work) So far, this has been a fun process & I haven't broken anything.
The one thing I'm stumped on at the moment is what material to use to re-seal the glass to the bucket. It looked like JB Weld, but I'm pretty sure it's not. Any ideas?
Can you powder coat them in clear after you have them nickle plated?
Not sure. Not all powder coat will hold up to high temps, and the ones that will are just a few colors. Even if clear was, I'm not so sure it wouldn't yellow over time.
The powdered aluminum process is how these were originally done, so that probably works best.
Great work! You can easily polish the lenses too, the I'm sure you're already doing that. I had the entire windshield polished on a 928 a few years ago, easily done with the right products
I did this rehab too but am going a different path.
I had purchased a pair of the plastic lens from Roger more than a year ago. I also purchased a mini D2S morimoto projector to use instead of the bulb.
I cheaped out and didn't buy their LED version. Doh!
Nice write up. I have an extra set of H4's that I stashed away just in case any pending issues and they could use a bit of a refresh.
I fully agree with 8" lights. I read somewhere that this was one of Ferry Porsche's demands with the initial design of the car. I found that using a Hella 100/80 watt bulb (Amazon) works best for me. ( off road use only ) oh no! They really throw out a long high beam that you will have trouble out driving. Also to keep the glass lens from rock chips or worse you might want to add a layer of 3M clear headlight adhesive . Same with the fog lights
Yes, I agree.
I am currently working with a plastic molding co to get me one with clear center. They have one of my plastic lens for reference.
Could be costly though.
01-10-2018, 07:06 PM
H4 headlight restoration
