Gen 3 Coupe Windshield Problem

[rutherforda65]

My glass guy has installed my windshield twice and both times after being exposed to sunlight the black border has separated from the glass. We think the problem may be due to the fact that the curve of the glass does not exactly match the curve of the windshield frame. In order to install it flush we have to pull the outside edges down between 1/8 to 1/4”. Has anyone else had this problem and how did you solve it?

[edwardb]

Mine also required some pressure on the outside edges to sit properly in the opening. Probably about the 1/8 - 1/4" you're describing. Heard/seen the same with other builds. So the fitment I think isn't uncommon. However, first I've heard of the black border separating. Mine has been good for almost two years now (knock on wood) and has been in the sun plenty of times. I couldn't find a glass company that would do mine. Didn't want to touch custom work. But turned out a couple guys in our local club worked in the industry so helped me. We used Dow products. The black frit material was Black Betaprime 5504G. Adhesive was Betaseal Xpress. The glass has to be thoroughly cleaned before applying the black primer. Once we had the windshield installed and pulled into place, using some straps and padded blocks on the ends, they recommended leaving it that way for a couple days. Which I did.

[michael everson]

Both of my recent builds needed the windshield pulled into place. My glass guy also needed to sand it smaller in the middle top and bottom because it didn't fit in the opening. Neither pulled away that I am aware of.
Mike

[FFinisher]

Both of my recent builds needed the windshield pulled into place. My glass guy also needed to sand it smaller in the middle top and bottom because it didn't fit in the opening. Neither pulled away that I am aware of.
Mike


Hey, he is MY glass guy, Not yours, !!;););););););)

[David Williamson]

Mine was the same. I used the same method that Paul did but mine did lift slightly in the lower right corner. So far I have not done anything with it. One thing I did was use the stick on foam that comes with the kit to make a dam to hold the urethane in the groove when the glass was installed. Not sure who's method my wife and I followed but it might have been from Matt's 65 build site.
David W

[FracAG1980]

I have not started my build yet and this may be a stupid question, but with all the body work that needs/can be done to get gaps looking good and spoiler on smoothly or with a built-in look and other things looking right, could you build up the portion of the window opening that does not fit to where it will fit? If you are talking 1/8 - 1/4" is all that is needed.

[David Williamson]

yes you could build up the "A" pillars and blend it in to reduce the windshield curve. It would be lots of fitting but could be done.
David W

[jdavis500]

I have my body painted. If I scuff up everything nicely, it seems like I could use HSRF as filler and sand for a more flush fitting. It would all be out of view. Could that be a good alternative plan to putting the windshield under tension for the life of the car?

[FracAG1980]

I have my body painted. If I scuff up everything nicely, it seems like I could use HSRF as filler and sand for a more flush fitting. It would all be out of view. Could that be a good alternative plan to putting the windshield under tension for the life of the car?

I agree, with the body already painted the options are fewer. I also agree that the windshield should be installed in a relaxed state. Under tension or torque any rock chip will turn into a crack faster. Since I have never done this before I am just thinking about options. I have seen some threads that show that a lot of sanding/molding and fitting are necessary on the rear glass, so I thought the same might be tried on the front glass. Tension and torque on the rear glass is not as critical as the front, but probably should be minimized as well. Being a newbie I am certainly not going to advise what you should do. Please let me/everyone know what the solution you use and how it turns out.

[edwardb]

I don't know the exact count, but there have been a bunch of these Coupes built. I know that all versions have used this same 1986 Jaguar XJS windshield. That's what Factory Five told me. I have no experience other than with the Gen 3, so I can't say if the previous gens fit any better. But here's my opinion -- strictly FWIW. Clearly the OP has an adhesion problem since it's delaminated twice. Looks like David did too. But don't know if that's between the glass and the black surround. Or where it bonded to the body. Not minimizing when it happens. I would sick if mine let go too. But this has not been reported as a widespread problem. Maybe not panic over these reports.

What I can do is report what I was told when mine was done. The two guys that helped me worked for Dow and as I stated earlier and in my build thread, worked in the industry. They've spent their careers gluing in automotive glass and testing. Often crash testing so their work didn't last long. But that's another story. When they volunteered to help me install my Coupe windshield, obviously I jumped on it because I had never done anything like that before. The first and probably biggest issue with the Coupe windshield is it doesn't have the black surround (frit) like most current modern windshields. It comes from the time when windshields were installed with rubber gaskets and chrome molding. So no frit. Installing it without the surround wouldn't look great because the underlying body and urethane adhesive would be exposed. After looking this over, and me voicing my concern about painting on the surround and whether it would adhere to the glass, my guys said that was the least of my problems. They said the product they used (Dow Black Betaprime 5504G referenced earlier) formed a molecular bond with the glass and would not come apart if properly prepped and applied. There are other similar products (3M is quite common) but they used Dow for obvious reasons. They were actually more concerned about the adhesion to the fiberglass in the body itself. So we thoroughly roughed that up with 180 or 220 grit paper (don't remember exactly) and also primed with the same material. They also were adamant that although urethane grabs almost instantly and is designed so cars can basically be driven away after a new windshield is installed, they wanted me to leave it clamped for a couple days just to make sure everything thoroughly cured. Because of the slight gap and tension. They weren't too concerned about that BTW. Said it's not uncommon. Within reason. Also, don't minimize that fiberglass over time moves around and takes a set when under pressure. I've seen this is a number cases. Obviously can't say if that's the case here. But I wonder if the glass really stays under tension over time. All random thoughts I guess. So far mine has been OK, as stated before.

As an aside, I also chose to put rubber trim around my windshield. This was gleaned from other build threads, and I used the Flexline UM1913BR 19mm Windshield Auto Glass Universal Molding Flexible Trim Rubber recommended by others. In addition to looking a little better (once again, my opinion...) it makes the windshield kind of a press fit into the opening. Is there any chance that helps hold in place? I don't know. But can't hurt.

[J R Jones]

Long ago I had a 1974 Corvette that cracked a windshield slowly crossing a driveway ramp at a 45 degree angle. The windshield replacement guy stated it was because the steel "birdcage" frame had rusted, putting stress on the glass.
The lesson was not lost on me. I recently had to replace flat windshield glass in a street rod (repaired) steel frame which (freshly chromed) was not a perfect fit. I had to sand the glass to fit and eliminate pre-load.

[mtwarog]

Hi,

It's not clear to me exactly what is separating and where. Perhaps a picture might help.

As for my coupe, looking back at what I wrote, the sides on mine were sticking up about an inch, but the windshield easily flexed and the urethane/black primer has held so far (knock on wood).
Whether it was actually an inch, I can't recall, but I do know it wasn't perfectly flat.

Here are the pictures and descriptions of how I installed mine.
https://thefactoryfiveforum.com/showthread.php?25341-Matt-s-Gen2-65-Coupe-Build-Thread&p=297310&viewfull=1#post297310

Don't forget to test out the windshield fit before painting your car or you may end up having to sand off your new paint to fit the windshield. I used rubber trim on mine, so it's hidden, but I was nervous when sanding/filing that I would slip.

Thanks.
-Matt