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| $$$$$$$$$$$$$ WOW! More updates on Fiero GT Tail light lens!!!! $$$$$$$$$$$$$$ (Page 30/115) |
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kgoodyear
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SEP 18, 11:03 AM
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| quote | Originally posted by lorennerol:
I'm glad the plastic is tough, but I'm wondering about UV resistance as well. The OEM lenses might be somewhat brittle, but they weather much better than modern headlight lenses, which yellow, craze, and oxidize.
The oxidation can be sanded/buffed out, but the color shift and crazing cannot. Are you doing any accelerated UV testing on the plastic compound? |
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The lenses are made of poly carbonate with an added UV inhibitor and a fire proofing compound. This is the same material used in bullet proof applications. Specifications are available on the UV effects on PC that can apply directly to the lens. We have added an additional UV inhibitor to the compound to make it even more UV resistant. Testing the lens itself would not really produce any different results that are not already associated with the raw material.[This message has been edited by kgoodyear (edited 09-18-2018).]
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Thunderstruck GT
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SEP 18, 01:29 PM
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George obviously knows his chit! 
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railshot
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SEP 18, 06:04 PM
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I for one would prefer the polycarbonate lenses over acrylic due to the fact that when acrylic gets cold, it is quite easy to break and stress.
There are some quite impressive videos of motorcycle windshield impact tests that I have found, and polycarbonate wins hands down in all of them when it comes to impact resistance.
I am pretty sure that is why polycarbonate is used for headlights.
Here is just one example.....
https://youtu.be/sCYtjp_RQ9s
Most of the dull headlights we see are due to the protective coating / clear coat being worn off of them from road debris, rocks, and chemicals etc. attacking them.
Yes, UV will also add to the issue, but plastics have improved considerably when it comes to resistance to UV even without a coating.
They can be polished and re-protected, but I would suspect that the tail lights will see far less of the destructive forces that a headlight does.
Cold temperatures like we get up here are probably the cause of most of the stress cracks.
When loading the trunk, removing items, or even pushing the car, (which hopefully we never have to do  ) people have a tendency to lean on the lenses.
This may be why so many lenses I have seen have all the stress cracks in them?------------------
There's one in every crowd, and usually it's me. 
1988 Solid roof GT!
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Shho13
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SEP 18, 09:14 PM
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Yeah, I assume that the reason a lot of Fiero lenses cracked, as well as GTs lenses becoming delaminated was due to them being pushed by people that didn't know any better...
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"Discord"
Red 1988 GT under restoration!
Let's Go Mets!
( ͡° ͜ʖ ͡°)[This message has been edited by Shho13 (edited 09-18-2018).]
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kgoodyear
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SEP 18, 09:35 PM
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| quote | Originally posted by Shho13:
Yeah, I assume that the reason a lot of Fiero lenses cracked, as well as GTs lenses delaminaing was due to them being pushed my people that didn't know any better...
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A common way of cracking a lens is by pushing or leaning on the curved edges of the lenses. After the UV light has cooked it the plastic becomes quite brittle and can easily cause spidering that can lead to holes and more cracking.
Delamination:
Now, the decoration of the lens was originally sonicly welded to the clear part of the lens. Generally, this gave a large area for the two to bond. Nature though has other ideas and can create tremendous forces when the clear part of the lens is heated with the black decoration of the lens. The expansion coefficient is not the same, therefore, one expands and contracts faster and to a greater extent than the other setting up tremendous forces the sonic welding can not hold and if it did, it would cause other problems as well. So, in my humble opinion and observations it is the different expansion coefficients that will cause the delamination. Also, you will often find the delamination starts at the top side of the lens. I suspect this is because it is more often exposed to the direct sunlight.
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Goody
The beauty of a solution lies in its simplicity
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2.5
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SEP 24, 01:27 PM
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| quote | Originally posted by kgoodyear:
A common way of cracking a lens is by pushing or leaning on the curved edges of the lenses. After the UV light has cooked it the plastic becomes quite brittle and can easily cause spidering that can lead to holes and more cracking.
Delamination:
Now, the decoration of the lens was originally sonicly welded to the clear part of the lens. Generally, this gave a large area for the two to bond. Nature though has other ideas and can create tremendous forces when the clear part of the lens is heated with the black decoration of the lens. The expansion coefficient is not the same, therefore, one expands and contracts faster and to a greater extent than the other setting up tremendous forces the sonic welding can not hold and if it did, it would cause other problems as well. So, in my humble opinion and observations it is the different expansion coefficients that will cause the delamination. Also, you will often find the delamination starts at the top side of the lens. I suspect this is because it is more often exposed to the direct sunlight.
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Temp change and UV are my first thought as well.
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railshot
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SEP 29, 12:12 PM
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Just a bump for this very important part and project!
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kgoodyear
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OCT 10, 12:10 PM
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 ------------------
Goody
The beauty of a solution lies in its simplicity
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Jfrost
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OCT 12, 10:34 AM
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Thanks for the update and keep up the good work! I, as well as many others, are really looking forward to these coming out and appreciate your commitment to quality and doing things right. ------------------
Project L67 Fiero
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Kitskaboodle
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OCT 12, 06:54 PM
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kgoodyear made a comment above which I feel is only half correct.
GT tail light delamination and/or sun burning happens more at the top of the lens because if you think about it, the Sun is at its hottest temperature range between the 12 to 2:00 position. So, it's not just direct sunlight. It's heat and sunlight together. Just wanted to voice my opinion.  . Kit[This message has been edited by Kitskaboodle (edited 10-12-2018).]
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