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One of the pitfalls of hanging around this forum long enough is that you might start believing your own press. Although we've done plenty of GTV's in the recent past it suddenly occurred to me that I have no idea how to install a glue in front windshield - we have always replaced the glass with the available gasketed style. I really didn't think too much about it and called in the local windshield installers. They looked at me as though I was from Mars. They had no idea how to do it either!

So, can anyone share the best procedure for installing the front windshield glass? Much appreciated!
 

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Yes, give to a competent glass guy! Honest, the process Franks of Berkeley used to use I wouldn't want try. Involved lots of cleaning, glue, and nylon straps holding it in, wrapped around the car, overnight. The the same for the trim.

During this period (71-74) there must have been other companies using similar installations methods; I wouldn't think it's that unusual.

Andrew
 

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Discussion Starter #3
Yes, give to a competent glass guy!...
Absolutely my plan. But I'd like to be able to know the procedure in order to evaluate the competency of the installer. At least the guys that I called in knew their limitations. What scares me is the guy that says " oh yeah, no problem" and the next I know I've got black urethane prints on the headliner and a windshield That sticks proud of the body on one side, sunken on the other side and leaks like a sieve...
 

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Rich, does the Alfa windscreen use urethane?
The 1973 Lotus Europa I installed used butyl. It was fairly straightforward, managed to do by myself which probably wasn’t too smart.
Joe
 

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Discussion Starter #5
Joe, I have spent the last half hour reading about windshield installation so of course now I'm an expert. Butyl vs Urethane is about as hot a topic as Weber vs Spica is around here.

Some use butyl tape, others use urethane sealant, others use both. The later are considered heretics and should be burned at the stake. As far as I can tell, at some point (I'm thinking late sixties) a very involved production technique using Urethane was implemented primarily for unibody vehicles. The windshield was a designed structural piece intended to aid in roll over protection. (I assumed the change from gasket was a cost savings move...) Butyl does not provide the structural strength and hence the Urethane camp considers the butyl boys to be murderers in waiting. And the combo kids... Best not to even mention them...

The issue with using Urethane is that it is not a DIY friendly process. Unless you have a robot application system it is really hard to get it right.
 

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It’s my understanding that the “roll over“ protection isn’t so much as structural as it is to prevent the windshield from popping out and having a large aperture that a person can get ejected through in the event. Using butyl therefore provides no more protection than a gasketed windshield; using urethane will provided the added passenger protection.
 

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"It’s my understanding that the “roll over“ protection isn’t so much as structural as it is to prevent the windshield from popping out"

I have read that the windshield structural stiffness properties were included as load bearing elements in the finite element models of the chassis in order to raise the load bearing capabilities of the entire body structure in order to better meet ever increasing safety requirements. This, according to the papers I have read in the past when I was doing this sort of thing for things which fly.

I don't know how much they worry about people being ejected through the open windshield area in a crash since all should be wearing seat belts, and modern cars come with multitudes of airbags in all directions. Plus, hitting a windshield with your head, perhaps even going through it, can be pretty bad in itself.
 

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Discussion Starter #8
What's interesting to me is that there are no changes to the steel structure of the car, gasketed or glued in. So all the analysis would have originally been done with gasketed glass. When the fed cranked up the rollover requirements they must have been able to meet them by just changing the size of the glass and the glue. That had to save a ton of money not having to redesign the structure...
 

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you glue the molding on the winshield first, with clamps over night . then glue the winshield on the car. fill any small openings with sealant. and clamp over night .
 

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Paul Gynn (Rowley, MA) has the 'official' clamps used to install glued-in front glass, and I’ll bet he has done a few in his time. I think he also has a set of NOS trim. You might give him a ring to see if he's interested in parting with this stuff (search Glynn Motorsports, Rowley, MA).

John
 

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I’m having a hard time understanding how the glass windshield could provide any structural stiffness under bending. Nor how the glass would not be under some type of bending in any analysis with its complex curves. Perhaps a thick flat pane glass for an jetliner windshield would be suitable for such an analysis... but the GTV windshield will crack at just the thought of anyone trying to remove it for reuse.

I believe the change to glue in windshield was due Section 393.60 Subpart D—Glazing and Window Construction of the Federal Motor Carrier Safety Administration DOT Regulations
§ 393.60 Glazing in specified openings.
(a) Glazing material. Glazing material used in windshields, windows, and doors on a motor vehicle manufactured on or after December 25, 1968, shall at a minimum meet the requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 205 in effect on the date of manufacture of the motor vehicle. The glazing material shall be marked in accordance with FMVSS No. 205 (49 CFR 571.205, S6).
(b) Windshields required. Each bus, truck and truck-tractor shall be equipped with a windshield. Each wind- shield or portion of a multi-piece wind- shield shall be mounted using the full periphery of the glazing material.

Federal Motor Vehicle Safety Standard (FMVSS) No. 205, “Glazing materials,” (49 CFR 571.205), specifies performance requirements for the types of glazing that may be installed in motor vehicles. It also specifies the vehicle locations in which the various types of glazing may be installed. The purpose of FMVSS No. 205 is to reduce injuries (e.g., lacerations) resulting from impact to glazing surfaces, to ensure a necessary degree of transparency in motor vehicle windows for driver visibility, and to minimize the possibility of occupants being thrown through the vehicle windows in collisions. FMVSS No. 205 applies to passenger cars, multipurpose passenger vehicles, trucks, buses, motorcycles, slide-in campers, pickup covers designed to carry persons while in motion and low speed vehicles, and to glazing materials for use in those vehicles.
 

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As soft and flexible as auto glass is, glued in windshields still do stiffen up a vehicles front structure. Try twisting of compressing a piece of auto glass with your hands. It’s got a little bit of strength, right? Under transient compression and bending loads glass does behave stiff enough to add to the stiffness of the body shell.
 

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my 74' appears to be gasketed, I have not heard of a glue in Windshield. Interesting
Your GTV started life with a glued in windshield, as mine did (1973). Like many do, I changed mine over to a gasketed type when I restored the car. I believe glued in started in 1971 with the 1750 US models.

@gprocket , Rich... curious, what was your decision based on to use a glue in after so many gasketed installs? Was it availability or are you after originality?

Thanks
 

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Discussion Starter #15
It was strictly an economic decision. This wasn't a full restoration - more of a freshening. The original glass cracked but we had a good back up in stock and the trim cleaned up nicely. When you add up the cost of a new gasketed size windshield, shipping, gasket and trim it's a haul...
 

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Here’s one possible procedure based on a different car but of the same vintage... it’s a pretty general and basic method for glueing in a windshield using Product ID: 3M 08620.

Relevant info from mark 13:05 to 16:30 on

Once the windshield is set, the trim would get fit and set with tube caulking/adhesive, and then the four trim caps cover up the gaps at the trim ends.
 

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Discussion Starter #18
While I don't dispute the importance of a windshield in a modern car as part of the restraint system that includes the airbags, I'm not convinced that the Alfa engineers considered that as part of their design envelope in the early sixties. Alfa adopted the glue in windshield in the late sixties in compliance with federally mandated changes. Often tacking on something to a previously balanced design has unintended consequences. It would be interesting to see if lives were saved after the glue in windshield came on line specifically with GTVs.
 

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We would never know that result.

I do remember reading an old SAE report which did discuss the finite element modeling of car bodies and the addition of the glass structural properties to help stiffen the chassis.

I also think that because Alfa had problems with corrosion around the front and rear windows in many of their cars, as I witnessed in a couple of my Alfas, they more than likely welcomed the glued in window technology, if nothing else to avoid that problem.
 

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One of our local Alfa experts said the glued in windshields cause more rust problems because the trim would rub thru the paint around the opening. Indeed this is exactly what happened on my otherwise rust free GTV
 
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