[78w72]

Originally Posted by TAKerry

2021-11-01_02-23-32 by Kerry Grubb, on Flickr

Exactly like 78w72 described

yep.. thats how it looked when he did it. pretty quick & easy process that with a little practice to get the bead right i think most people with some mechanical ability could do it. & he didnt heat the tube but it was a warm summer day. he did however have a electric powered caulk gun for the 3rd one he did, must have got tired of doing it with a hand powered one.

heres the 3m stuff, "window weld" i used on the rear glass & same stuff he used on the front but was a larger tube. i got the smaller tube at auto zone i think.

https://www.3m.com/3M/en_US/p/d/b40067015/

[Greg Reid]

Originally Posted by dataway

Do you feel it didn't seal because it was too hard or lumpy, or because it was too difficult to apply?

Perusing some Amazon reviews, there appears to be three different 3M products which vary in viscosity. Many reviewers were saying leaving the tube in the sun, slightly heating with a heat gun and it would come out nicely ... also mentioned to make sure the entire foil seal under the nozzle is punched out.

The standard 3M urethane (not fast cure) mentions that it is "medium viscosity" and "easy to extrude" ... which is not mentioned in the fast setting urethanes which only say that a manul 18:1 3M gun can be used.

I'm betting the pros use the fastest setting stuff than can so the customer can get the vehicle back in use. The standard product requires much longer to cure, might not be suitable for "drive-in" or emergency window replacement.

You know what is bizarre ... kids are using this stuff to rebuild all kinds of suspension bushings and engine mounts on their imports. They center the components in situ and just pump in the urethane and let it harden. Some pretty impressive claims about how well it works and how long it lasts in these applications. Quite possibly a similar urethane to what manufacturers are using to make these bushings and mounts.

In my case it just didn't flow well enough to seal and it took me way too long to get it all the way around the perimeter so it had started to set up before I could even place the glass.
I can believe that you could make bushings out of it. I was not aware of this material until I started removing the glass in question. It was the back glass of a 74 trans am. The way I described it at the time was that it was just like cutting through tire rubber. It is definitely tough stuff and I would not shy away from using it again with the knowledge I have now. I also did not know about the different viscosity levels available.

[78w72]

the 3m stuff i linked to worked fine in a normal caulk gun & when i did the rear glass in my 72 it was this time of year in a shop that was about 65-68*f. but im sure warming it will help it flow better.

i didnt notice any different viscosities, just bought what they had at auto zone that was the same product i linked to above which states can be used in powered or standard guns. just like with any caulk, the size of the opening makes a big difference on how easy it will come out, for the front windshields to get that 1" tall bead, its a very large V shape thats cut into the tip. for the rear glass i did it was about a 3/8 angled cut. i didnt have any clumping or issues with curing before i got it all the way around the window.

[dataway]

I could use a good photo of that V notch ... I'm a bit unclear as to how it's orientated to the surface when you apply the adhesive. Is the V cut in the "trailing" edge of nozzle so that as you drag the nozzle the sealant "follows" your nozzle, and the height of the V helps determine the height of the bead? No dam is needed on the inside of the glass to prevent ozzing and set glass height?

Jeez this thread has given me a lot to think about.

1. I'm not great with things that come out of nozzles

2. I'm pretty good with tape like products

3. I'm even better at watching an expert do something

[dhutton]

Originally Posted by dataway

I could use a good photo of that V notch ... I'm a bit unclear as to how it's orientated to the surface when you apply the adhesive. Is the V cut in the "trailing" edge of nozzle so that as you drag the nozzle the sealant "follows" your nozzle, and the height of the V helps determine the height of the bead? No dam is needed on the inside of the glass to prevent ozzing and set glass height?

Jeez this thread has given me a lot to think about.

1. I'm not great with things that come out of nozzles

2. I'm pretty good with tape like products

3. I'm even better at watching an expert do something

This is not a job for amateurs imho. I’ve seen pros make a heck of a mess doing old car windshields with urethane. And there are no easy do overs or repairs.

Butyl is more DIY friendly imho assuming you can get past all the warnings and hype about butyl.

Don

[pfilean]

Anyone do one on a 61 bubble-top?

Yes

A few years ago I needed to repaint around my 61 bubble top rear window. I was getting some rust bleeding out from under the trim every time I washed it. Was not leaking into the trunk yet and I wanted to stop it before it did. Went to a local glass installer and told him I wanted the glass out and after I cleaned up the channel around the glass I wanted it back in. He was of course to come to my garage both times but they often do this in parking lots to no big deal and no rain issue. If I remember right he quoted $100 out and $100 in which sounded fair and I was to supply a new Steele gasket which was a little over $100.

Sand blasted and painted the channel but wanted the glass back in before I wet sanded and buffed the paint as I didn't want a lot of water and compound getting all over the interior. Glass shop guy came out for a few hours for each of three days and even brought the boss out once. After much cussing and swearing and re-setting the glass a few times and using a couple of tubes of the 3M bedding compound they thought it was finally done.

When I sanded and buffed the paint I found the glass leaked "like a sieve" around the whole glass. Took it into their shop and the installer "troweled" more 3M around the glass and thought it was done. Still leaked so I cut the glass out and wasted the new gasket and ordered another one.

Got an old friend to come out and we "roped in" the glass with the new gasket using the 3M which can be messy but mine didn't leak. But it was a mess to clean up and I swore if I had to do one again I might use bees wax as a seal as I think that was what the factory had used.

That having been said, I just finished putting a new gasket in the windshield of my son's 53 Chev pickup using the 3M. It's easier on the truck flat glass and the 3M doesn't leak. But can still be a mess to work with.

[dataway]

Did anyone else use the dam on the inside of the glass when they installed with urethane? Seems like a good idea, sets the height of the glass and prevents it from squishing out to the inside so it's visible beyond the trim.

[78w72]

Originally Posted by dataway

I could use a good photo of that V notch ... I'm a bit unclear as to how it's orientated to the surface when you apply the adhesive. Is the V cut in the "trailing" edge of nozzle so that as you drag the nozzle the sealant "follows" your nozzle, and the height of the V helps determine the height of the bead? No dam is needed on the inside of the glass to prevent ozzing and set glass height?

Jeez this thread has given me a lot to think about.

1. I'm not great with things that come out of nozzles

2. I'm pretty good with tape like products

3. I'm even better at watching an expert do something

sorry i didnt get any pics when mine were done, maybe TAKERRY has some other closer pics, you can almost see the height & shape of the bead in his pic. best i can describe the cut in the tip is a V shape, or more of a <, about 3/4-1" long. when applying the bead he was pulling the gun away from himself. the bead was about 3/4-1" tall. when the glass is laid in the bead doesnt ooze out much, maybe a small spot in a upper corner that is easily trimmed after cured, nothing went to the outside channel area & the glass sits nice with the trim.

heres a vid i found on a quick search, im sure theres many others. you can see the shape of the cut for the tube at about 1:16.

https://www.youtube.com/watch?v=oaSM-srTDV4

or this

https://www.youtube.com/watch?v=lkkzoIzFdu8

[TAKerry]

Sorry no other pics. Maybe you can zoom in on the one I posted. What 78w72 describes is exactly how it played out. I did not see the guy cut the nozzle. He had 1 tube that had a small amount that he started with, then used a full tube and finished with a third. I have done a thousand miles worth of caulking in my life and thought the bead as it was coming out was really neat and something I have never seen. I figured the tubes were made that way. They were very consistent between the 3 tubes he used. He did have a ryobi battery powered caulk gun. Temp was in the mid to low 60's yesterday. If I ever need another windshield I will def give this guy a call. Seems like a no brainer. Its how I describe doing drywall work. Its not hard to do, but super easy to screw up.

[dataway]

Very helpful, thanks.
I'm clear on the notch now ... I see they are cutting it in only the trailing edge and holding the tip in contact with the pinch weld so the stuff comes out like Play-do coming out of their extruder toy.

I think I can do that no problem ... I wonder about the window height though, I've got a video saved where they do use blocks in one (that they leave in the urethane) and a dam on the other to set the glass height which is important on old cars so the space between the trim and the glass is correct.

I'm seeing some videos where they apply the sealant to the body, others where they apply it to the glass.

[78w72]

Originally Posted by dataway

Very helpful, thanks.
I'm clear on the notch now ... I see they are cutting it in only the trailing edge and holding the tip in contact with the pinch weld so the stuff comes out like Play-do coming out of their extruder toy.

I think I can do that no problem ... I wonder about the window height though, I've got a video saved where they do use blocks in one (that they leave in the urethane) and a dam on the other to set the glass height which is important on old cars so the space between the trim and the glass is correct.

I'm seeing some videos where they apply the sealant to the body, others where they apply it to the glass.

i think the ~1" tall bead puts the glass at the right height to the trim, at least for 2nd gen firebirds, but other cars of the same era have about the same depth in the channel.

ive seen it aplied to the glass too like in the last vid i linked, but i think thats for newer cars, late 60's through late 70's ive always seen it applied in the channel. maybe call a local glass company & see if one of the techs will confirm how tall of a bead they use for cars like this to get the correct glass height?