the windshield on my 71 is original and showing signs of delamination at the outer vertical side areas. Is this a common occurance or is there a problem with the frame (bird-cage). There is no evidence of this vehicle being stressed by collision. The delam is minor and not effecting view. Would it be wise to leave as is or is this frouned upon by critics? Happy Holidays to all.
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Re: C3 Windshield delamination
Here's the story... The windshield frame on early Shark cars is an Achilles' Heel issue that can be a REAL PITA to address. Prior era Corvettes used a rubber gasket around the WS glass and either encased the assy in a frame (C1 era) or pulled the assy inside the WS frame. Shark cars laid the glass on top of the WS frame and used a NUMBER of sealing agents to protect the final assy.
Frequently, a prior owner took his car to 'Bubba' for a low cost windshield replacement and short cuts were taken with respect to sealant use. Over time and use, exterior water driven by car-in-motion wind ran across the glass and puddled at the upper/outer extremes seeking a way to invade....
If invasion was sucessful due to the lack of proper sealant, the windshield frame rusted through, then acted as wick/straw to hold water. This can generate rust through of the windshield frame (and other bird cage members) from the inside out. With a rotted windshield frame, you can have a loss of rigidity that allows the glass to flex too much with one possible side effect being delamination.
To really tell whether or not your car falls in this category, the windsheild needs to be removed, the windshield frame cleaned and the integrity of the underlying metal visually inspected. Sometimes there's SO MUCH rust present that MAJOR surgery is required....
This consists of doing a windshield frame 'transplant'. You determine the points where there's still good frame metal left and cut there. Then, using a non-rusted donor windshield frame from a wrecked Corvette, you cut and weld to replace the rotted portion of your your car.
These jobs typically consume 12-20 labor hours to execute properly, meaning this isn't a cheap fix... Let's hope that isn't what is going on with your car! -
Re: C3 Windshield delamination
Here's the story... The windshield frame on early Shark cars is an Achilles' Heel issue that can be a REAL PITA to address. Prior era Corvettes used a rubber gasket around the WS glass and either encased the assy in a frame (C1 era) or pulled the assy inside the WS frame. Shark cars laid the glass on top of the WS frame and used a NUMBER of sealing agents to protect the final assy.
Frequently, a prior owner took his car to 'Bubba' for a low cost windshield replacement and short cuts were taken with respect to sealant use. Over time and use, exterior water driven by car-in-motion wind ran across the glass and puddled at the upper/outer extremes seeking a way to invade....
If invasion was sucessful due to the lack of proper sealant, the windshield frame rusted through, then acted as wick/straw to hold water. This can generate rust through of the windshield frame (and other bird cage members) from the inside out. With a rotted windshield frame, you can have a loss of rigidity that allows the glass to flex too much with one possible side effect being delamination.
To really tell whether or not your car falls in this category, the windsheild needs to be removed, the windshield frame cleaned and the integrity of the underlying metal visually inspected. Sometimes there's SO MUCH rust present that MAJOR surgery is required....
This consists of doing a windshield frame 'transplant'. You determine the points where there's still good frame metal left and cut there. Then, using a non-rusted donor windshield frame from a wrecked Corvette, you cut and weld to replace the rotted portion of your your car.
These jobs typically consume 12-20 labor hours to execute properly, meaning this isn't a cheap fix... Let's hope that isn't what is going on with your car!Comment
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Re: C3 Windshield delamination
Michael,
I have the same situation on my '71. Not a big deal, original paint and non accident body.Comment
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Re: C3 Windshield delamination
Michael,
I have the same situation on my '71. Not a big deal, original paint and non accident body.Comment
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Re: C3 Windshield delamination
Windshield delam is certainly not as common on the C-3s as it was on the earlier cars, especially the earlier C-1's. The good news is that it is not directly connected with the condition of the birdcage. It can be connected, but is not necessarily so.Comment
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Re: C3 Windshield delamination
Windshield delam is certainly not as common on the C-3s as it was on the earlier cars, especially the earlier C-1's. The good news is that it is not directly connected with the condition of the birdcage. It can be connected, but is not necessarily so.Comment
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Re: C3 Windshield delamination
Michael, I have to disagree with Jack's conclusions on possible delamination of a windshield attributed to a weakened pinchweld/birdcage. If a birdcage is weakened it is more likely to crack a windshield not delaminate it. When a windshield is made it is constructed of an inner and outer lite of annealed glass that is a laminated construction with a PVB plastic interlayer (poly vinyl butyral) This PVB material acts as a glue to hold these two lites of glass together. Delamination can happen to a windshield immediately and it can happen over time. The reason it happens immediately is usually a mismatch in the bending between the inboard lite of glass and the outboard lite. As someone mentioned delam is more prevalent on a wrap around deep C1 curved windshield where mismatch is greater and tolerances were not as tight, a C3 has a very flat design, and had tighter tolerances....what typically happens on a C3 is that over time the PVB releases at the edge for a host of reasons, one is the old bending issue and the PVB is bonded weakest at the edge, but also because of oxidation, contamination entering and attacking the lamination and other factors. Think what plywood would look like after an edge was submersed in water for a week? Eventually the delamination will continue, not much you can do. The C3 did not have factory glue sealing the lamination or edge of the windshield, the glue was bonded to the inboard light and birdcage. I myself have a repop C2 windshield in a gasket set that is delaminating for no reason other than it is poor quality bend. Delam occurs from poor bending mismatch and intrusion of contamination and weather at the outer edge of the glass.
The other comments I can make is that delamination is a real problem on the ZR1 only windshields because LOF used a metalized coating for Solar control purposes and the metallic coating oxidizes and delam's and begins to get milky and cloudy, any of you ZR1 owners have a milky windshield?
Also when a glass shop does a replacment and cuts out the C3 Windshield they use razors to cut through the polyurethane or polysulfide, quite often the razors can cut through the metal leaving rust to form in the years to come if not treated properly during replacement.I agree with Jacks assesment that water leaks will destroy a C3 birdcage, but also any scratching of the green zinc coat bearing unprotected steel will destroy it as well....thats what a cold knife, or windshield cut out tool will do to it.
Hope that helps.Dino LannoComment
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Re: C3 Windshield delamination
Michael, I have to disagree with Jack's conclusions on possible delamination of a windshield attributed to a weakened pinchweld/birdcage. If a birdcage is weakened it is more likely to crack a windshield not delaminate it. When a windshield is made it is constructed of an inner and outer lite of annealed glass that is a laminated construction with a PVB plastic interlayer (poly vinyl butyral) This PVB material acts as a glue to hold these two lites of glass together. Delamination can happen to a windshield immediately and it can happen over time. The reason it happens immediately is usually a mismatch in the bending between the inboard lite of glass and the outboard lite. As someone mentioned delam is more prevalent on a wrap around deep C1 curved windshield where mismatch is greater and tolerances were not as tight, a C3 has a very flat design, and had tighter tolerances....what typically happens on a C3 is that over time the PVB releases at the edge for a host of reasons, one is the old bending issue and the PVB is bonded weakest at the edge, but also because of oxidation, contamination entering and attacking the lamination and other factors. Think what plywood would look like after an edge was submersed in water for a week? Eventually the delamination will continue, not much you can do. The C3 did not have factory glue sealing the lamination or edge of the windshield, the glue was bonded to the inboard light and birdcage. I myself have a repop C2 windshield in a gasket set that is delaminating for no reason other than it is poor quality bend. Delam occurs from poor bending mismatch and intrusion of contamination and weather at the outer edge of the glass.
The other comments I can make is that delamination is a real problem on the ZR1 only windshields because LOF used a metalized coating for Solar control purposes and the metallic coating oxidizes and delam's and begins to get milky and cloudy, any of you ZR1 owners have a milky windshield?
Also when a glass shop does a replacment and cuts out the C3 Windshield they use razors to cut through the polyurethane or polysulfide, quite often the razors can cut through the metal leaving rust to form in the years to come if not treated properly during replacement.I agree with Jacks assesment that water leaks will destroy a C3 birdcage, but also any scratching of the green zinc coat bearing unprotected steel will destroy it as well....thats what a cold knife, or windshield cut out tool will do to it.
Hope that helps.Dino LannoComment
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Re: C3 Windshield delamination
Michael,
If indeed your windshield is the original, based on your description of the delamination, I would leave it alone. I think many windshields that old are cracked as they are taken out( I'm told they become very brittle) and the foam sealing strip that was used as a dam for the sealant is difficult or impossible to find to use when you re-install. Do love to see the original part still in place.
Regards,
Alan71 Coupe, 350/270, 4 speed
Mason Dixon Chapter
Chapter Top Flight October 2011Comment
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Re: C3 Windshield delamination
Michael,
If indeed your windshield is the original, based on your description of the delamination, I would leave it alone. I think many windshields that old are cracked as they are taken out( I'm told they become very brittle) and the foam sealing strip that was used as a dam for the sealant is difficult or impossible to find to use when you re-install. Do love to see the original part still in place.
Regards,
Alan71 Coupe, 350/270, 4 speed
Mason Dixon Chapter
Chapter Top Flight October 2011Comment
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Re: C3 Windshield delamination
If you want to remove a factory windshield the best chance of removing it is with a wire cut out method, it is a piano wire with grit on it with T handles and use it as a hack saw one person from the inside and one from the outside and you can keep from cracking the original glass which is easily cracked. You need to bring your car to an autoglass shop who has an old timer and be willing to pay some money...The foam dam tape is readily available in the autoglass business from parts houses. I would guess most folks want to tak ethier original out to repair the VIN plate area on the A pillar....best seek a pro for th ebest chance of success.
Interestingly enough you can repair delamination by heating the glass area up to 300 degrees and clamping the delamination area when the plastic remelts, it will rebond, of course if you heat too much the plastic will blister and the windshield is destroyed, if you clamp to hard the glass will crack, I don't recommend this.
I am not sure if everyone knows that glass cracks and bullseyes can easily repaired without replacement. Windshield repair is a process where you evacuate the damage and inject a resin/glue that is cured with UV light which fills the void to eliminate the appearance of the crack or damage, then there are pit fillers as well....so before you toss out a cracked or rock damaged windshield, repair it....Some repairs are totally invisible....then use jewelers rouge to buff out pits and wiper scratches and you will have restored your glass. Tempered side glass and back glass is a different story, they can be buffed slightly but not repaired. Don't throw away cracked original windshields repair them, it is worth the $100 repair attempt.Dino LannoComment
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Re: C3 Windshield delamination
If you want to remove a factory windshield the best chance of removing it is with a wire cut out method, it is a piano wire with grit on it with T handles and use it as a hack saw one person from the inside and one from the outside and you can keep from cracking the original glass which is easily cracked. You need to bring your car to an autoglass shop who has an old timer and be willing to pay some money...The foam dam tape is readily available in the autoglass business from parts houses. I would guess most folks want to tak ethier original out to repair the VIN plate area on the A pillar....best seek a pro for th ebest chance of success.
Interestingly enough you can repair delamination by heating the glass area up to 300 degrees and clamping the delamination area when the plastic remelts, it will rebond, of course if you heat too much the plastic will blister and the windshield is destroyed, if you clamp to hard the glass will crack, I don't recommend this.
I am not sure if everyone knows that glass cracks and bullseyes can easily repaired without replacement. Windshield repair is a process where you evacuate the damage and inject a resin/glue that is cured with UV light which fills the void to eliminate the appearance of the crack or damage, then there are pit fillers as well....so before you toss out a cracked or rock damaged windshield, repair it....Some repairs are totally invisible....then use jewelers rouge to buff out pits and wiper scratches and you will have restored your glass. Tempered side glass and back glass is a different story, they can be buffed slightly but not repaired. Don't throw away cracked original windshields repair them, it is worth the $100 repair attempt.Dino LannoComment
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