Windshield seal and sealant as I keep kicking "that 1980 C10"

[JohnnyPopper]

I removed the windshield seal and found there was some real agressive rubbery mastic behind it. It had sealed the drain holes and I have some rust to deal with.    Plus it took some work to cut it down to a surface I can work with.

Q: Is the mastic stock? Or was this an rookie bonehead move?

I question it because it will (unless there is a methodology to it) inevitably plug the drain holes.

I've installed seals in other resto projects windshields where it wasn't used and the windshield sealed fine.

Finally, as an aside, the 'Store' lists two windshield seals for under 50.00, both the plain and the chrome lock strip. Is this a factory replacement?

[MY1978]

Hey JP, where are the drainage holes located under the seal.  I might should check mine. 

[Mike81K10]

There should be two drain holes under the windshield seal just before the curve in the lower corners. The holes are about 1/8" in size and should be open to prevent rust out. There should be no reason to have a sealant under the rubber except perhaps a very small amount on the edge of lip to hold it in place while you install the windshield. Sealant is the enemy of your windshield and should only be a temporary fix.

[JohnnyPopper]

Thx Mike, so some rookie caused all this rust 

[VileZambonie]

Windshield urethane is required when a glass company is installing a replacement windshield. Installation without it can result in crazy lawsuits. If a windshield is ejected and the roof collapses after the windshield was installed, guess who is getting sued?

Read post #3 http://forum.73-87chevytrucks.com/smforum/index.php?topic=35095.0

You do not need to apply the urethane to the frame gasket as there is a pinchweld seam. The urethane is applied to the glass so no need to even have urethane near the drain holes.

[JohnnyPopper]

Thanks VZ, makes sense after I read through the thread.

So use Urethane everywhere between the frame and seal Except where the drain holes are.

Like 2 inches on either side of the hole?

[JohnnyPopper]

the 'Store' lists two windshield seals for under 50.00, both the plain and the chrome lock strip. Is this a factory replacement?

Better question is: will this replace my gunked up and brittle seal?

http://store.73-87chevytrucks.com/merchant2/merchant.mvc?Screen=PROD&Store_Code=7&Product_Code=WCR848&Category_Code=WTHR

[VileZambonie]

You do not need to apply the urethane to the frame gasket as there is a pinchweld seam. The urethane is applied to the glass so no need to even have urethane near the drain holes.

The frame gasket does not need any sealer unless you are having water coming in. The area that an installer is required to use urethane is where the glass contacts the gasket.

To install the new gasket, you line it up at the bottom where the gasket seam is with the center of the opening. Like where the antenna hole is in the dash and the lock strip clip goes. Firmly press on and install the gasket all the way around onto the lip. Go around 20 times making sure it is fully seated otherwise you will break the windshield trying to install it. I like to do this in the sun so that it is hot and pliable. If you are using urethane, you put a light bead all the way around the inside of the gasket, install the glass and then install the zipper. Start the zipper dead nuts in the center or your clip will not be centered.

[JohnnyPopper]

Got it, so this was a mistake to use this Gorilla glue under the gasket. Thanks!!!

Have you used the window seal from the store? (hope I'm not putting you on the spot?)

I haven't gotten a reply to my question so this might be a way to get it answered...

[VileZambonie]

The gasket sold here? The description looks like it's the gasket with either a black or chrome lock strip. I am not sure what brand it is. PM Captkaos and ask him.

[JohnnyPopper]

Thx man

[silencer]

Hi, I'm new to the forum so forgive me if you've got your answer.
Windshields were the family business, and we used to change these out (848 if I recall) in 7 minutes. Super easy to work on.
I've done hundreds. Typically a good gasket will be all that is needed. Once the sun hits the rubber, it tends to stick itself to the new glass. We use a 'fibrestick' to break that seal so that we can pop the old glass out.
Sometimes if a guy is working alone outside, I've seen installers pump a small amount of butyl into the pinchweld part of the gasket to hold it in place if the wind catches it and or it sags with no glass in it, but it's never used as a sealant, or to hold the gasket onto the pinchweld, nor would you use it on the glass / gasket as it will prevent that 'bonding' that I spoke of earlier.
If say the customer wanted to fix a leak himself, they would DIY by inserting butyl into the top of the gasket. This doesn't work, and often caused leaks. We never did this, as a leak was a sign of a physical issue like a torn gasket, rust, etc.  or that the chrome insert strip was not set correctly, or that it shrank due to UV. Regardless, we would need to remove the butyl to fix the leak. If we couldn't get it all out, the windshield usually leaked at that spot. At that point you needed to start with a fresh gasket and slap the customer's hands for their 'butyl' fix.
When the newer non-square body models came out, the '1011 if I remember my stock numbers', some shops ripped off customers by using butyl tape kits instead of OEM urathane to install them. (For about 2 years we were repairing bad installations, some just a few days old... the customers always had the same experience - it started leaking and whistling - they'd take the truck in and the 'shop' would just pump a bunch of butyl in as a 'fix').  As soon as the sun hit the glass, it would slide, hit the support blocks and usually crack. This also caused leaks, noise, structural weakness and some deaths. This did not mean, however, that the previous style, the 848 square bodies needed urethane, nor was there any lawsuits when using stock or OEM instructions to install, so I think one of your commenters misunderstood that. I lived it, and never heard of such a thing in my industry. Possibly the law in the US was different, but in Canada there was no requirement to use urethane in the squarebody gaskets, that I knew of. That being said, if you are going to put urethane into the glass slot, make sure the bead is well flattened so that it doesn't deform the gasket and leak. If you do it right, it won't 'hurt' anything, but urethane doesn't bond to the gasket very well, if at all. It just ends up being a loose strip of rubber that can allow the entry of water and dirt (it will peal off like a bandaid so I have trouble imagining that someone made a regulation to use urethane for 'safety' as it's not bonding to the gasket). If there's some law now requiring it, well, do what you can. The squarebody glass, just like a school bus, is designed so that in an emergency, from the inside you can put your feet on the glass, push, and escape the vehicle. It was not designed for butyl or urethane, nor do those products 'improve' anything in a squarebody. They just cause leaks and eventual rust, especially of the floor as the water tends to pool under the carpet. You might not see the leak, but as the gasket turns on the bottom, the water dumps behind the dash and then rusts out the floor.
So, when replacing the windshield  1) clean the pinchweld 2) deal with rust if you can 3) unplug any drain holes 4) clean the gasket - or replace it if it is stiff or cracking 5) use silicon spray when installing the glass and chrome insert (yes it is factory) and lastly let it sit facing the sun so that the rubber can reform to the pinchweld, the roof line, and bond to the glass. If it leaks, remove the chrome insert, and use your fibrestick to reseat the gasket to the metal. Don't use any butyl, tube silicon or urethane, and it should stay leak free until your next change.
One more thing - if you do need to pop the windshield out (easily done without risk of breaking) to work on, say the dash, if you did put urethane into the gasket, you are going to need to get it all cleaned out, as the loose urethane will bunch up on reinstall, not seat properly, then cause an unnecessary leak.
Lots of info, hope it helps someone.

[Scott91370]

I searched the Federal Motor Vehicle Safety Standards (FMVSS) page and couldn't find anything related to urethane being required. 

It was on mine when I removed the window for paint/body but it was not used when reinstalled.

[VileZambonie]

In the mid-late 90’s I worked at a Chevrolet dealership that also had a body shop. GM issued technical data regarding improper windshield installation techniques resulting in lawsuits and warned all dealers of the risk associated with improper install techniques especially since most were subletting the work to glass companies. Even if a sublet was used to install, the dealership was still liable in an ejection incident. During the insurance companies' mandatory training, which included the contracted glass company we were using, it was made clear that unless it specifically said not to use windshield urethane, that it was to be used on all replacement windshields. It also required compliance with proper urethane types and primers if required. So regardless if it originally came through without it, unless you could find where it was printed stating, “do not use”, then it was to be used on every install. Now whether or not you use it is up to you, but the lawyers are always out there waiting to sue. On your own ride, it’s your choice, but as an installer, you are rolling the dice if something does happen. Look at the multi-million dollar lawsuits constantly plaguing the auto industry. A garage that dares to plug a tire to save their customer a few bucks could be having their going out of business sale. (Mossy Ford) Even documenting an inferred “multi-point inspection” results in loss of millions as we just saw recently with nothing more than a glossed over tire inspection that didn't notate dated tires. So the whole point I’ve tried to make clear is that a business who installs a windshield without the use of urethane faces the risk of major lawsuits. These trucks are not exempt as you will not find anything from GM stating not to use it. It’s CYA

For the record, I couldn’t care less if people do or don’t. I’m just making it clear why informed glass companies started using the urethane adhesive on all windshield installs including on these trucks.