The Stovebolt Site Forums The Shop Area Paint and Body Shop Windshield rubber question...

Help topics here and videos on YouTube conflict with the installation process in the AD shop manual as well as what was done in the 1960s and I'd be interested to know what is behind the change.

Specifically, the shop manual tells you to apply masking tape around the perimeter of the outside and inside and then says:

Apply a continuous 3/16" bead of 3M "Weatherstrip Adhesive" along the outside rabbet pinchweld, completely around the windshield opening. Fig 5--which clearly shows the sealer filling the outer part of the space between the weatherstrip and the cab metal.

Then the explanation of installing the glass into the weatherstrip piece and the cord pulling process is provided and:

After the assembly is in position, seal the weatherstrip to the glass and in the opening using 3M "Weatherstrip Adhesive" in a sealing gun
(a) seal between outer lip of rubber weatherstrip and glass completely around the opening
(b) seal under the outer lip of rubber weatherstrip where it rests on the body metal completely around the opening
(c) seal under inner pinchweld lip of rubber channel completely around the opening
(d) remove any excess "adhesive" by using oleum spirits sparingly.

What happened? I see where these guys on YouTube are sealing the glass to the weatherstrip after the windshield is installed. Some of them don't apply the sealant to the outside rabbet but apply to the gasket. Some of them apply the sealant to the pinchweld slot in the gasket. None of them go back and seal the outer lip where that rubber rests on the body. Why? This was always done in the past and that was because this rubber doesn't seal against the cab, water will enter around the perimeter and will sit there, and natural capillary action will draw water up behind the rubber strip. That rabbet/ledge angles back where water won't drain well from it. I'm curious. Why isn't anyone sealing like the manual instructed? Thoughts? Ideas?

Further to this, I went out and cut a section out of a weatherstrip piece I removed (replacing windshield now) to show how it sits when installed. The pinchweld is in the slot as far as it can go. In this case, you can see there is a gap of about 1/16" at the rabbet ledge and the lower ledge as well. Using GM's method, the rear edge of the seal piece will be filled as well as the lower part. Using the YouTube video method, none or very little of this area will be filled.

I started out in the glass shop in 1975 when all the trucks and vans as well as a lot of cars had gasketed w/s as well as back glasses and quarters. I was taught by the guys who started in the 60's. On a rope in set we put the gasket on the glass, then chromes if it had them. Next the rope went in, starting at the center bottom followed by a bead of bedding and glazing from a caulk gun. After the glass was in we would seal between the glass and rubber. If the caulk is put on the body you usually end up with it on the inside lip of the rubber as well as your rope, hands and everywhere else. If the glass is sealed to the rubber it tends to want to slip all over while you are roping it in. After the glass was in we would run our thumb around the outer edge of the rubber, adding some caulk if necessary.

The FAM is great, but many times experience in the field comes up with a different method which achieves the same result. Also, the modern sealants aren't quite the same as what we had then, probably because of EPA regulations. FMVSS have all but eliminated gasket sets and require the use of urethane on most if not all stationary auto glass, Hopefully my not so clear, long winded explanation helps. One thing I've found with YouTube is you don't have to know what your doing to make a video and post it! Also, what works and is easier for me may be harder for you than your way. As long as you get the job done without hurting yourself, causing damage and its safe and doesn't leak the end result is the same. John

You posted the pic while I was typing. To expand on my post, the caulk bead goes on in the 90 degree groove that contacts the roof and flat section of the body. which does the same as placing it on the body first, but with less chance of a mess. Now I'm probably as clear as mud! John

Thanks John,
I'm ok with that all that (and I realize the sealer today is mostly urethane), but unless you apply more than 3/16" bead, there's going to be nothing at all at the lip of the seal (where it meets the cab body. I tried this with a section of old weatherstrip and 3/16 will barely fill the top part of the rabbet ledge. So a lot of space remains to harbor water, dust, dirt, leaves, whatever. Do you think (with today's sealer) that going back and running more under the gasket makes sense? Also if you started in 1975 then I'm certain you remember the applicator used to seal the rubber to the glass...the little oil-gun looking thing with the duck bill flat nozzle that fit between the glass and rubber. Are those still around today?

John, just to be certain I'm on the same page, are you talking about running the bead of sealant where the yellow arrow is pointing?

That's the place. Run about a 3/8" bead. That might be a little heavy, The bottom doesn't need to be quite as heavy. When cleaning up wipe in one direction with your rag. Don't have it wringing wet with solvent.If I can be of any more help I'll try. If Texas was a little closer I'd run over and help you. John

Thanks much, John. I wish it was closer also. Your summers are nicer than ours. I'm a few weeks away from installing but will let you know how it goes. The cord I have is something like 4mm in diameter. That should be ok, yes?

I had to look at a ruler to see how big 4mm is. That should work fine but I'm not sure about using metrics on a 52 American made truck! One thing I forgot to mention was lubing the lip that pulls over the pinchweld. We used silicone unless we were in a bodyshop, but I've found that a foamy aerosol glass cleaner works just as well and cleans off the glass better, Murphys Oil Soap also works good. John

Maybe a shaving gel (like Edge or something)? Sorry...I got in the habit of thinking in metrics in the 50s (watchmaking work) and it stuck with me.

I would follow the manual exactly. My guess is that YouTube is unreliable, don't have a manual or can't read it. It is kind of hard to figure out what a,b and c says. But they put the sealant everywhere. The YouTubers may be filtering there more recent era techniques. I did not look at any YouTube on this subject.

Just to be clear about the tape. You put the tape on the inside of cab before removing old rubber to prevent scratching inside. This "locates" the tape right next to the rubber. The odd part is that it seems like, in the sequence, removing that tape is the last thing. It would seem like the additional sealer they tell you to apply would be on top of the tape at that point? On the inside of cab.

I also noticed that they say to install rubber onto glass after applying sealant to cab. I have only done a few TF windshields, I always install the rubber on the glass for a week or two. Tape it on to train it. Preferably in a warm place.

In 1952, I don't know if a "apply a 3/16 bead" means 3/16 wide or tall. If it means wide, how tall would be variable according to how it is dispensed by the user and what kind of tube opening. The reason I mention this is that it has to do with volume. If there is a 3/16 wide bead with no "volume", it won't fill the voids.

Glass cleaner is good. I use it when applying silicone around bathroom shower glass jobs and etc. WARNING!!!! Use only the foam glass cleaner WITHOUT AMMONIA!!!!!!
This includes Windex. I don't know if ammonia affects 3M adhesive.

Good point about the glass cleaner Bartomos. I do know that ammonia and urethane adhesives don't mix per the mfgs. The only time I've put tape on the body was with a light colored paint job that we weren't sure if the sealer would stain the paint because it hadn't fully cured (not the most comfortable position to be put in). I don't know what the sealers were that were used in the 50's, but they seem to be different than what we had in the 70's, just like todays are slightly different. Also, when you are doing something everyday you like to stick with the same product as much as possible because you know the working characteristics. John

I'm pretty sure 1952 3M sealer is not the same as 2020.

Well, in the 1960s and through the 70s, there were two sealers used for two purposes. There was a tar-like black compound that never really dried and was in a tube with a tapered end. You cut the end off to produce the size of bead you wanted just like today's caulk cylinder and squeezed it out like toothpaste. If it took you 20 minutes to get the windshield in there, you had no time pressure. Then there was a cap you screwed back on when you were finished. If you got this on your hands, mineral spirits or turpentine would remove it. Then there was a liquid that came in a red tin can a little wider in diameter than a soda pop can with a screw top. You poured this into what looked like an oil gun and applied it between the rubber and the glass when everything was in place but before you went back and added more of the tar-like sealer under the seal piece. The liquid dried fast and stuck the rubber to the glass. You had to follow yourself with a rag and be careful with that stuff because it would damage paint. The windshield I removed recently was still stuck fast to the rubber piece after 40 years. The end of the applicator was about 1/2 or 3/4" wide and maybe 1/32" thick. It looked like a duck's bill and slid between the glass and rubber. I guess that went by the wayside, but it was a pretty neat gizmo. Attached is a picture showing that stuff still on the glass. It was applied in 1979.

What non-hardening sealant would you use today? And what between the glass and rubber?

The last rubber set I did was a Chevy II and I'm pretty sure I used 3M Part No. 08509 Bedding and Glazing. I was able to get the caulking tube tip between the glass and rubber to seal that area also. It seemed to be real close in viscosity to the old days. I used the same tube for the pinchweld side of the gasket first, so don't cut your tip too big. TJohnhe oil can (we always called it a Plews Gun) was way handier and faster. I don't know if they even still make those, much less the different sealants in a can that were used with them. I'm starting to feel old now.

John, I read about 08509. It claimed it set in one minute. I'm not sure what that means, really. Sounds like you need to get the rubber pulled in and over the pinchweld pretty chop-chop and it doesn't usually happen that way for me. Maybe 8 or 10 minutes per side...possibly less but never in 1 minute. Ideas? Thoughts?

I don't think it sets up but I may have the wrong part no. I will check tomorrow and post back. I think I left a partial tube at my nephews where I did his Chevy II. I'll get back on this tomorrow afternoon. I wonder if you goog;ed 08609? That's a fast set urethane showing a 10 min. time. Urethane is fine as long as you never want to reuse the gasket if a windshield gets broken. John

Thanks, John...that's fine. There's no rush. I'll be traveling for a few days but should have internet access. I'm just trying to understand what would work the best here. I do understand the urethane would bond rubber to metal, glass, etc...probably pretty much without the ability to reuse anything. 10 minute working time ought to be ok. I think.