To "Glue" or-not-to "Glue!
 

I am in the process of replacing my front windshield seal and wanted to get opinions on whether to "glue" it or not? I have read several posts notating to "Glue" in the windshield to avoid rust issues down the road.

Thanx,

Serge

No glue, new gasket.

Depends on the model year; the 964 (and later?) units were glued at the factory.

Yes glue, my new gaskets leak

...There, its a tie ;)

I received the following recommendation and I just used this on another model car as a test.
Going to redo my new seals on my 1973 911, and yes, I did use the recommended seals but still got tiny visible leaks under the right conditions.

I got this recommendation from somone here. This is what I will use when I redo them one more time.

3m Auto Bedding and glazing compound.
(I guess technically it is not a glue, and can be more easily removed and cleaned up later)

P.s. I am also the one who started the thread on why seals should be a regular maintenance item.
I don't know anyone who has removed and installed glass as many times on the same single car or exposed it to as many elements as I have for research purposes (versus for paying customer purposes). Each time I have removed it and replaced it with yet another new seal I find evidence of moisture even in areas where I had not detected the initial leak.

I really think gluing it would be double-assurance of it not leaking.

This is for an 86 Carrera.

Got the thread link?

I'm of the same mindset(already replaced a ton just because it is a 30 year old car) and I would love to see your thoughts on it.

Wayner, I did have an opportunity to have read your lengthy thread, and that is why I bring the question up. Thanx for the research.

Serge

My other thread mainly documents the carnage.

This current thread that we are on is a good place to ask and debate the issue. Thanks for starting it Serge

I think this applies to all 911/912 cars up to but not including 964s

Here is the other thread
http://forums.pelicanparts.com/porsche-911-technical-forum/686953-why-windshield-trim-should-regular-maintenance-item.html

Huh,
Installed mine without glue, works in downpour that overpowered the windshield wipers on high. The seal was the Pelican aftermarket one as well, proper install was/is the key. Glue will not solve for improper installation.

Don't do it. If installed correctly with the OEM gasket(avoid the a/m gaskets), the windshield will not leak. I replaced mine last year. The old gasket had been "glued" more than once. I spent 3-4 evenings in the garage cleaning all that crap up. New glass, new OEM gasket, old trim. Half hour to install and zero leaks in 12 months and 10k miles. -J

I installed my new seal without glue. I used a method recommended by another Pelican of tapping the aluminum trim ring at the corners to move the seal over into place. I haven't driven it in the rain nor do I plan to so I can't tell you if it leaks or not. I personally don't see a need for sealant if the new seal is installed properly.

I'm curious then why the factory installed seals eventually leak?

JAR, of course I am concerned with the leaking effect, but trying to be proactive and avoiding the water creeping in between the seal and the car and begin the "rotting" effect.

AGE, the seal is not a lifetime part. Rubber ages, and then shrinks, causing leaks.

Just for reference, I am not a big fan of urethane to glue these but I really do like how the 3m glazing compound that I mentioned above works with these seals

I'm going with "shrinkage" and the fact that some owners don't pay attention to how the seal mates to the window frame and allow gaps to open up without addressing them.

I've installed 20 or more no glue no leak. If you glue it have fun trying to remove it.

Well if you have ever had the unpleasant experience or the windshield blowing out at at around 150mph then you'll glue it. My 85 had the window try to blow out during a high speed run. seems the cabin was pressurized by the air coming in the front vent. I could see daylight around the bottom passenger corner. Pulled it out got a new gasket and glued it in.

According to my manual (Haynes) "From Dec. '69 USA models have a glued-in windshield.... Your Porsche dealer will be able to supply the glue...."

I didn't glue mine in when I replaced my seal in '85 and haven't had any problems, but I avoid rain.

My car arrived to me with the windshield and old seal in the back seat. I re-installed the old crappy seal after scraping off the old sealant with the 3M glazing compound just where the seal will lift off the outside all the way around it.
3 years later, no leaks.



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That 3m glazing compound is what I have been experimenting with on another car, and am ready to try on the 911 when I do my next reinstall test this summer. Maybe I even got the 3m recommendation from you?

I should also mention that in my testing, my car has been exposed to +80 degree weather in the summer and -40 degree weather in the winter (inside an unheated garage).

Not everyones experience will be the same as what I am seeing with the rubber seals cycling through these extremes.

Also, I have purposely left my interior unfinished as I experiment so I can detect even minor leaks.

What I am seeing with my latest install (still no sealant but apparently a good dry install) is that if I look really hard I can find tiny minuscule droplets that from inside the car midway down the inside edge of the rear trim (where the rubber seal meets the side panel that is covered with headliner). By the time they get to the bottom of the glass near the parcel shelf they often have dissipated and leave no pool inside the car on the parcel shelf, but do leave moisture inside the seal.

If I leave the car out in the weather for days, the water that pools outside on the lower rear corners of the glass eventually seeps past the seal and onto the parcel shelf (normally hidden by carpet). As the new seal ages that will get worse.

With the design of the rear glass in particular, I do not trust the seal to stay tight and dry, giving the design of the rear window and these external naturally pooling areas on top of the glass (at the lower corners) that just don't dry up on their own until things really warm up or you soak them up from the outside of the window with a rag. Those pools are deep, and due to the high humidity in my area, they even form on the glass some days (mornings) when it doesn't rain.

At this point I have concluded that as Timmy2 suggests, using 3m glazing compound or similar product to act as a flexible, thin, non hardening membrane between the seal and the glass, or the seal and the body is the ounce of prevention that these cars need if they are regularly used and exposed to the elements. I see no down side. It can be cleaned up more easily than urethane sealant and will adjust with the shrinkage and expansion of the seal with weather or over time.

I see no reason not to use it on the front windshield as well (unless you want to use a more permanent glue to stop movement).

Aside from being a little bit messy (I plan to mask my Alcantera dash during install) it helps the seal slide into place more easily.
As I researched this product I also came to the conclusion that for people that aren't ready to replace their seals, they could mask off their window and painted areas (easier cleanup, but it wipes right off anyway with mineral spirits) and apply it as Timmy2 describes. Maybe the old seals can live to work another day without replacement.

Here is the picture thread again. Pay particular attention to the picture of the black 964 if you think that it is all about the rubber seal.
(Yes this is a scare tactic).
http://forums.pelicanparts.com/porsche-911-technical-forum/686953-why-windshield-trim-should-regular-maintenance-item.html

P.S.
There are other opinions for various reasons and I respect those, so please keep the discussion going if anyone has anything to add. I am anxious to explore this further.

This how-to article was just posted by 3litre on another thread here.

They use the same non hardening 3M glazing compound

I am adding it here for future reference

Window Glass Install - Modified Mustangs & Fords Magazine