For much of the automotive age, all U.S. car buyers had for road-lighting options were sealed beams. These eventually came in round and rectangular shapes, but they were all as flat and upright as a chest of drawers from Ikea. At the same time, drivers in other nations had headlamps that integrated into the design of the car, rather than the other way around. This provided better aerodynamics and as a result, higher fuel economy.
We can thank Ford for bringing the composite headlamp to America as it was that company that spearheaded the effort to get the Federal Government to (pun intended) see the light. The 1984 Lincoln Mark VII became the first car legally sold in the U.S, with plastic lensed composite lights. It didn’t take long for almost every car and truck sold here to follow.
Now we have headlights that are model-specific, which raises another issue, that being the cost of replacing one should a rock smash the outer lens or time and wear render it so miasmic as to be dangerous. Plastic headlights are the rule not the exception today and that has opened a whole new can of worms that we didn’t have to deal with during the sealed beam days. What do you think, do the benefits of plastic lights—weight savings, aerodynamics—outweigh their downsides?
Image: lamin-x
Hooniverse Asks: Are Plastic Headlights a Plus or a Plague?
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The condition of some of the yellow, opaque lenses I see on the street is truly scary. It seems odd in retrospect that the lenses you threw away when the bulb burned out were durable glass, and the aero lenses that are expected to last the life of the vehicle are easily crazed and UV-degradable.
Sealed beams were cheap, ubiquitous, and had the lens integrated into the bulb so it was easily replaceable. On the other hand, they were a bit of an aerodynamic barn door (or pedestrian slicers in the form of pop-ups) and trying to style them could be… well, um…
http://assets.blog.hemmings.com/wp-content/uploads//2013/09/1985-EXP-Front-Right-2-700×478.jpg-
I’d like to see the EXP reimagined with round sealed beams and complementary sheet metal.
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Done. Its the Nissan Juke.
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You could replace those old sealed beams, with European “quartz iodine” lights and blind every one. So much so that I had to lower my low beams because everyone thought I had my high beams on.
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If you bought the right kind, you were good. I used to run Cibie’ Z-Beams in my Vega. Of course I also had to swap the sealed beams back in at inspection time, because the Z-Beams weren’t DOT marked.
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Aero headlights are beneficial to designers as well as aerodynamics and fuel economy.
Making them out of plastic sucks, but is economically practical. I’d prefer them to be made of glass, but plastic is cheaper than glass, and lasts long enough for most cars.
While automakers like to tout longevity, their cars aren’t made to last forever. The plastic headlight lenses last, in most cases, long enough for an engine to fail or a car to hit a tree.
For the rest of us, there is an aftermarket full of headlight restoration snake oil, or (technically not legal) glass replacement lenses from a euro-spec car.-
It is not like light covers are legally required to be plastic in the US?
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I can’t find anywhere in the FMVSS specifically forbidding glass lenses, but they do need to be DOT approved, and most DOT approved lenses are plastic.
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And, coming at the problem from the other direction, Euro-spec headlights specifically are not DOT approved. The two standards are fundamentally incompatible in terms of the pattern of output regardless of the materials used.
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Are you into this enough to explain how? Maybe that explains my personal vendetta against driving with fog lights and low beams on, which I recently discovered appears to be the way they are designed to be by US law, while having both sets on is unlawful in Europe. Somewhat counterintuitively, I’d expect this to be a blinding combination.
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Only in a very hand-wavy fashion. They differ both in terms of which directions must be illuminated, which directions must not be illuminated, and the distribution of intensity within the illuminated areas. In general the DOT pattern will send more light towards the illumination of overhead and roadside signs (which from an ECE perspective would constitute unwanted glare) and the ECE pattern will send more light along the outer edge of the roadway towards ground level than down the middle of the lane, whereas the DOT pattern will distribute this ground-level light more evenly. I’ve driven with both and although they differ, I can’t get all that worked up in the defense of either one over the other.
This is of course all very much simplified. I have done some graduate-level work with optics but IANAL (I am not a lighting or legal expert). -
Well enough explained for me, and it makes sense. I remember when I still was a teenager and bought car magazines, there would be scientific tests with good photos showing the different light image different cars emit. Didn’t find a good one now, but this little picture show from 2013, including a 1949 Mercedes 170V, is still…enlightening. Check out the Audi:
http://www.autobild.de/artikel/licht-test-3873702.html -
I once got pulled over at night in my ’37 Plymouth for driving without headlights. They were working just fine, but the officer had to examine them quite closely in order to convince himself of this. The cheerful yellow glow of its six-volt incandescent units was almost entirely lost among the wash of the streetlights.
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i believe the plastic material, instead of glass, comes from 5 mph inpact standards. our cars here have to minimize damage in low-speed impacts. plastic lenses don’t shatter.
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But aren’t most car fronts sort of rounded? On a flat barrier at least, you have to have a bit of deformation to get to the lights. Just speculation though.
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something something deceleration shock blah blah i don’t know i’m making things up now
i thought i read something about glass lenses shattering once
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I prefer my headlight pre-yellowed.
http://farm5.static.flickr.com/4142/4819652055_8d5eb08d13_b.jpg
(Not my car. I kind of wish it was.)
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I kind of wish it was too. In that way that you see a girl you know will suck the life out of you and lead you to an untimely demise but when you look at her it seems worth it.
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Yup. Totally worth it.
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http://www.alfabb.com/bb/forums/attachments/164-168-1991-1995/771202d1429398662-french-fogs-tempted-snap-2015-04-19-00.10.19.jpg
Jaune! Jaunt pour tout les lumiere!-
Our first foreign vacation after reunification of Germany: France. As a kid, I was shocked – SHOCKED! -by yellow highways. And in love. EU regulations “fixed” that.
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For most they are a boon. In the fringe corner of the automotive world that I occupy, where a ten year old vehicle is new, they are a bane, since by the time a car gets to me they are about due for replacement. That said, if headlights must be aerodynamic I’d prefer plastic to glass. The streamlined glass unit on my first-gen Acura Legend cost $650 to replace, in 1993 dollars.
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I’m with you on that one. I went through the whole sanding/polishing deal on my 05 Odyssey’s headlights, and got them looking much better, but still not perfect. I don’t think my equally-old 12v B&D cordless drill was up to the task, to be honest. It took an hour each side just to get them there, though.
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Ten year old vehicles still fall within the range of the hazy, distant future. They’re not yet old enough to be new.
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But those glass headlights are now making the Legend (and 4th gen Accord) look SO good. That’s what I always notice about those cars. Between the clean styling and the headlights that are still shiny, they look really timeless.
From what I have read in the past, it isn’t so much the plastic that is the problem, but scratch-resistant and UV-resistant hard coatings that applied during the manufacturing process. The one I was thinking of is polysiloxane, but the link below claims that polysiloxane is breakdown resistant, as it’s inorganic, and that the coatings that have problems are organic silanes:
https://www.tspinc.com/scratch-resistant-coatings/
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They’re also not colorless, which is why hazing is so obvious on clear plastic.
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but if you get a new tail lamp, and you keep the other one, it becomes really amazingly “clear” just how faded and hazed the tail lamps can get (did that on my “new” 1993 245, I’m going to have to get another tail)
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I started out my cubicle life in plastics engineering. Got into UMass-Lowell and promptly decided that marketing had more fun. I regret nothing.
Plastics are as good as you want to pay for them to be. Glass is awesome for heat, light and long-term clarity, but the expense and fragility are barriers.
The problem with plastic lenses is that there is a product guy somewhere in a burrow counting nickels, and if he can save one on a part that will be found on 400,000 cars a year, he’s just saved $20,000. Give him enough parts and he’ll make his unit profitable this year and no one will catch on to his scheme until 15 years goes by, the parts are rotting and he’s retired with waterfront property.
So the biggest problem is that when a part is designed for a 5-year use cycle, it will be designed for a 5-year use cycle.
I’ve had to replace sealed beam headlights that have had rock hits to the glass, but not one plastic one. It’s a trade off.
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And if you make the glass crack resistant by making it thicker and toughening it it does end up heavy
Why are these comparisons always made as if there are no alternatives other than sealed beams and plastic lenses? Other commented have mentioned the ‘universal’ lights with QH bulbs, and ‘aero’ glass lenses. Funnily the plastic protective covers for the latter did not yellow!
It seems that newer lights with free-form reflectors and ‘clear’ lenses do better, but they haven’t been around as long.
Ironically now that projector/HID/LED lights don’t need optical lenses, it would be more feasible to make them from glass again, for simpler shapes at least. Won’t happen of course when lights have to be such a major styling feature of the car, plus the added weight.
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I agree about the newer lights; it seems from about ~2004 to 2006 model years onwards I don’t see as many clouded or crazed-over headlight lenses as I do on anything older.
I see the benefit pf plastic. It is lighter, cheaper and I am not sure if they can “mold” glass into the funky headlight shapes we see today. Obviously they look like carp after a few years and there is little you can do to prevent it. Perhaps they should look for a more UV resistant plastic coating or at least design the units in a way that you can replace the plastic lens with a new one. Most headlights work fine, is just the plastic lens that gets damaged.
Are yellowing headlights somehow a US thing? I can’t remember seeing yellowed headlights in Europe, but then again I haven’t spent that much time in the southern bits. Is yellowing a problem in Canada?
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Yellowing happens in Canada, but we tend to use the same bits as US models, outside of the occasional bumper and gauges.
The really weird one was the Ford Escort ZX2, where only one headlight would yellow on any given model. -
I see Mercedes W210 cars yellowing outside US, but not as bad as US cars, totally fogged, etc.
Plastics going bad is a symptom of cost cutting rather than anything inherently wrong with the material. I’m sure if some accountant somewhere found a way to save a penny with a cheap version that makes glass disintegrate, you would have similar problems with sealed beams. One might also argue said accountant works for Apple, given the sheer number of cracked to shit iPhones I see on a regular basis, but I digress (and fully admit someone from LG or Samsung probably looks over their shoulder.)
Any questions?
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OOps…just went all tingly! Now, if the damn things would just turn with the steering wheel…
Timely question – I just bought a beater ’89 S-10 pickup and was quite surprised that the sealed beam headlights light the road better than the yellowed plastic units on my 1995 and 2005 vehicles. And they look better with nice clear glass. Obviously a lot of aero, weight, and cost benefits with plastic, but for pure lighting – the point of headlights – I give the sealed beams the win over the long haul.
Timely question – I just bought a beater ’89 S-10 pickup and was quite surprised that the sealed beam headlights light the road better than the yellowed plastic units on my 1995 and 2005 vehicles. And they look better with nice clear glass. Obviously a lot of aero, weight, and cost benefits with plastic, but for pure lighting – the point of headlights – I give the sealed beams the win over the long haul.
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Looks nice..for a beater. My ’93 also has the glass sealed beams, on which I replaced the OEM ones w/ halogens.
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Great looking truck! Mine does look decent, but mechanically it’s a beater – lots of issues. I bought it because I can wrench out the mechanical issues, repaint that nice straight body, and I’ll have a really nice work truck cheap.
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My biggest problem with modern headlights (aside from UV-fogged plastic) is the insane amount of disassembly that some require for replacement. Maybe ten years back, one of my wife’s coworkers mentioned to her that the dealership wanted $148 dollars to replace one on her early 2000’s car (might’ve been a Chevy Cobalt? Can’t remember) so my dear sweet wife volunteered me for it.
Ended up removing the bumper and popping the fender loose, all after pulling the plastic bits on the bottom off. Took me three hours. For one damned bulb.
I know that while this is not the usual (my minivan is fairly simple), it’s definitely not unheard of. I’m convinced that for every good engineer on this planet there are twenty or so morons who went into the field because only they were good at math and couldn’t figure out what else to do.
The wife’s coworker called me back a year later. The turn signal bulb had gone out. Was I free that weekend?
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I heard there has been a new EU reg since maybe 2012 where new model cars must have user changeable headlamp bulbs. No more pulling the entire assembly to change a bulb. Has anyone else heard this? I wish it were true.
The combination of sealed beams and glass covers worked for some brands for years without any problems.
http://cloudlakes.com/data_images/gallery/porsche-356/porsche-356-06.jpg
http://www.speeddoctor.net/media/2013/03/VW-Beetle-1300-19652.jpg
http://www.bustedvw.com/wp-content/uploads/2009/07/1961-vw-micro-bus-001.jpg
It’s fairly easy to polish out the haze. You should look after your paint, headlight plastic is of similar hardness
popularmechanics.com/cars/how-to/a2648/4252611/
http://2.bp.blogspot.com/-gQ09oefR3hg/TsUj99PlngI/AAAAAAAABhQ/VKN_0Ymk5b8/s400/light.jpg
The car polish people are now all over this
http://www.meguiars.com/content/global/product/2729_lg.jpg
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They haze up again in a year. I’ve held off the deterioration after a polish by sticking 3M clear film on them.
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I use ordinary high carnuba wax car polish and reapply every month. The hazing stays away in our very high UV sunlight, (2 to 6 times US levels)
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