Stress cracking headlight?
Le Mans Master
Joined: Dec 2005
Posts: 7,753
Likes: 210
From: North Western Connecticut
Yea OK certain conditions cause the plastic to go bad! What's extremely annoying is how the plastic lens were affixed to the housing! Absolutely NO REASON to do it the way it was done unless you planned on jamming owners when replacement time comes.... Very poor design because there are numerous inexpensive ways they could have been attached that didn't require an act of congress to get them off...... Should have been designed as a easy replaceable part for an owner to do..... 
Supporting Vendor
Joined: Sep 2007
Posts: 11,216
Likes: 178
From: Pensacola Florida GO GATORS!!! www.rlsebring.com www.c6c7vette.com
St. Jude Donor '17
Actually the headlights are highly engineered to withstand 200+ mph. That's the primary reason from the bonding standpoint as well as lift characteristics from the angle they are mounted.
Yea OK certain conditions cause the plastic to go bad! What's extremely annoying is how the plastic lens were affixed to the housing! Absolutely NO REASON to do it the way it was done unless you planned on jamming owners when replacement time comes.... Very poor design because there are numerous inexpensive ways they could have been attached that didn't require an act of congress to get them off...... Should have been designed as a easy replaceable part for an owner to do.....
Melting Slicks
Joined: Sep 2008
Posts: 2,360
Likes: 59
From: San Jose California
CTS-V's have this probelm as well, my co-worker has it starting on both of his headlights and told me it was kind of common for those cars.
He has never put anything Alcohol based on them, I do agree that a Alcohol product can have such an effect.
Example: One of the final test boys left an Alcohol bottle (full mind you, which leaked out) on my polycarbonate lid for my robot transfer chamber, and it was crazed in a few hours.
I wouldn't imagine that a dealership would use an Alcohol based product on cars sitting on the lot.
DJ
He has never put anything Alcohol based on them, I do agree that a Alcohol product can have such an effect.
Example: One of the final test boys left an Alcohol bottle (full mind you, which leaked out) on my polycarbonate lid for my robot transfer chamber, and it was crazed in a few hours.
I wouldn't imagine that a dealership would use an Alcohol based product on cars sitting on the lot.
DJ
Burning Brakes
Joined: Jan 2008
Posts: 1,171
Likes: 3
From: DFW Texas
Cleaners such as Windex have isopropyl alhohol in them. So if he has ever used a glass cleaner on his lights I am sure it would cause this over time. I would be willing to bet dealerships have used cleaners such as windex seeing most of the detail guys they use dont really know what they are doing.
Now as far as film goes we use an isopropyl alchohol and water mix for our tacking solution. I NEVER use this on the lights as I know what it will do. I use the soap and water mix... which takes a minute longer to set, but it doesnt cause crazing. For my bottles I have to use specially designed spray bottles because the alchohol eats the plastic on normal bottles. I cant tell you how many times I would go to pick up a bottle and the neck of it would break from the alchohol breaking it down.
Now as far as film goes we use an isopropyl alchohol and water mix for our tacking solution. I NEVER use this on the lights as I know what it will do. I use the soap and water mix... which takes a minute longer to set, but it doesnt cause crazing. For my bottles I have to use specially designed spray bottles because the alchohol eats the plastic on normal bottles. I cant tell you how many times I would go to pick up a bottle and the neck of it would break from the alchohol breaking it down.
Le Mans Master
Joined: Aug 2008
Posts: 5,578
Likes: 61
From: Austin TX
I don't know what causes the "crazing". But I did wrap my headlights to protect them from road rash. Just look at cars that have plastic headlights and that get driven alot. Most have a sandblasted look.
They've been wrapped for 18 months and 18,000 miles and they look perfect, except for one where a rock hit it and it has a small mark on the wrap.
As far as heat goes, I've touched my headlights after driving and I've never felt scorching heat. I'm going to drive it tonight and recheck.
They've been wrapped for 18 months and 18,000 miles and they look perfect, except for one where a rock hit it and it has a small mark on the wrap.
As far as heat goes, I've touched my headlights after driving and I've never felt scorching heat. I'm going to drive it tonight and recheck.
Last edited by AirBusPilot; Apr 24, 2011 at 09:41 PM.
Drifting
Joined: Mar 2010
Posts: 1,901
Likes: 361
From: TX
It isn't the chemicals that is causing the crazing. Its simply due to the heat output of the HID lamp building up inside the cavity and cooking the lens. You can duplicate the same thing by simply putting them in the oven at around 200 degrees or so. Don't let anyone tell you its because of the cleaner you use, cause they are flat wrong. While there are some chemicals, like amonia, that can cause some types of clear plastic to become cloudy, they don't cause cracking.
GM simply did a poor job designing the lights to be able to withstand the heat that they are subjected to. They either choose a poor material for the lens, or else didn't do enough to relieve the heat build up, or a combination of both.
It's simply a design flaw, and GM needs to have their feet held to the fire and forced to make good on it when it happens.
GM simply did a poor job designing the lights to be able to withstand the heat that they are subjected to. They either choose a poor material for the lens, or else didn't do enough to relieve the heat build up, or a combination of both.
It's simply a design flaw, and GM needs to have their feet held to the fire and forced to make good on it when it happens.
Last edited by CSixDude; Apr 24, 2011 at 05:56 PM.
Le Mans Master
Joined: Dec 2005
Posts: 7,753
Likes: 210
From: North Western Connecticut
All I'm saying is there are mechanical methods for doing it that would have made life a lot easier or oops.. must less expensive! GM figured the OP would have to toss them away and simply buy new ones! That's one hell of expensive option on a car that might only be 5 years old....
Team Owner
Joined: Jun 2005
Posts: 46,295
Likes: 2,596
From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
this is one of those endless discussions that really has all the answers contained herein as RL mentioned. it could be any or all of the above "causes." somehow, we will pay for it because I doubt an '05 or '06 owner is going to get a "warranty" replacement at no cost. and neither will my '08 shortly should it occur.
as to design for 200 mph, yes, it most likely is, but it definitely is not the only way. it may be the most cost-effective way which may have been the single reason for its current design.
if the specifications from GM were for: 200 mph, cost, AND ease of replacement, there would most likely be a different design altogether, and possibly different materials. if the specs had also included not to craze or deteriorate for say, 10 years, under most conditions, there might also be a "slight" design change.....
which would/might affect cost....
as to design for 200 mph, yes, it most likely is, but it definitely is not the only way. it may be the most cost-effective way which may have been the single reason for its current design.
if the specifications from GM were for: 200 mph, cost, AND ease of replacement, there would most likely be a different design altogether, and possibly different materials. if the specs had also included not to craze or deteriorate for say, 10 years, under most conditions, there might also be a "slight" design change.....
which would/might affect cost....
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Verdad Gallardo
Safety Car
Joined: Jan 2009
Posts: 4,681
Likes: 2
From: Mooresville (Race City USA) NC
this is one of those endless discussions that really has all the answers contained herein as RL mentioned. it could be any or all of the above "causes." somehow, we will pay for it because I doubt an '05 or '06 owner is going to get a "warranty" replacement at no cost. and neither will my '08 shortly should it occur.
as to design for 200 mph, yes, it most likely is, but it definitely is not the only way. it may be the most cost-effective way which may have been the single reason for its current design.
if the specifications from GM were for: 200 mph, cost, AND ease of replacement, there would most likely be a different design altogether, and possibly different materials. if the specs had also included not to craze or deteriorate for say, 10 years, under most conditions, there might also be a "slight" design change..... which would/might affect cost....
as to design for 200 mph, yes, it most likely is, but it definitely is not the only way. it may be the most cost-effective way which may have been the single reason for its current design.
if the specifications from GM were for: 200 mph, cost, AND ease of replacement, there would most likely be a different design altogether, and possibly different materials. if the specs had also included not to craze or deteriorate for say, 10 years, under most conditions, there might also be a "slight" design change.....
which would/might affect cost....
As usual, Bill has a balanced and insightful comment.
Melting Slicks
Joined: May 2006
Posts: 2,303
Likes: 40
From: Edmonton Alberta
Burning Brakes
Joined: Jan 2008
Posts: 1,171
Likes: 3
From: DFW Texas
Then by your logic I should have 100+ customers complaining to me that their headlights are crazing. Not to mention the thousands of headlights covered in this country that have film but no crazing. And what about the BRAND NEW Vettes sitting on the lot with crazed lights???? Sounds like your logic is a little faulty.
It isn't the chemicals that is causing the crazing. Its simply due to the heat output of the HID lamp building up inside the cavity and cooking the lens. You can duplicate the same thing by simply putting them in the oven at around 200 degrees or so. Don't let anyone tell you its because of the cleaner you use, cause they are flat wrong. While there are some chemicals, like amonia, that can cause some types of clear plastic to become cloudy, they don't cause cracking.
GM simply did a poor job designing the lights to be able to withstand the heat that they are subjected to. They either choose a poor material for the lens, or else didn't do enough to relieve the heat build up, or a combination of both.
It's simply a design flaw, and GM needs to have their feet held to the fire and forced to make good on it when it happens.
GM simply did a poor job designing the lights to be able to withstand the heat that they are subjected to. They either choose a poor material for the lens, or else didn't do enough to relieve the heat build up, or a combination of both.
It's simply a design flaw, and GM needs to have their feet held to the fire and forced to make good on it when it happens.
Burning Brakes
Joined: Jan 2008
Posts: 1,171
Likes: 3
From: DFW Texas
As I have Bren saying, there are numerous articles on the net noting not o use isopropyl alcohol on acrylic or transparent plastics. Here is one of the many links I found. Obviousely it's bot heat as I have been stating.
http://www.contentcaboodle.com/busin...f-acrylic.html
http://www.contentcaboodle.com/busin...f-acrylic.html
Supporting Vendor
Joined: Sep 2007
Posts: 11,216
Likes: 178
From: Pensacola Florida GO GATORS!!! www.rlsebring.com www.c6c7vette.com
St. Jude Donor '17
Well there you have it folks, it's IA and not heat at all responsible for every lens that has cracked, crazed or otherwise is ruined. Guess the thread should be closed now.
As I have Bren saying, there are numerous articles on the net noting not o use isopropyl alcohol on acrylic or transparent plastics. Here is one of the many links I found. Obviousely it's bot heat as I have been stating.
http://www.contentcaboodle.com/busin...f-acrylic.html
http://www.contentcaboodle.com/busin...f-acrylic.html
Last edited by RLSebring; Apr 25, 2011 at 01:49 AM.
Burning Brakes
Joined: Jan 2008
Posts: 1,171
Likes: 3
From: DFW Texas
Well I wouldn't actually close it but I think the way forward is to find out what is and isn't safe on acrylics and clear plastics. Most people do not know what the makeup is of the cleaners they use on their cars. I think it would be helpful and save a lot of heartache/money to find out what is safe to clean lights with.
