Setting glass - Butyl or Urethane? ... AAARG!!! - Page 2 - Chevelle Tech
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post #16 of 137 (permalink) Old Mar 17th, 12, 3:21 AM
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Re: Butyl or urethane... AAARG!!!

have seen a lot of urethane hack jobs by individuals who apparently didn't know what they were doing - usually glass that is sunken too low in the opening, with urethane dripping into the interior. Thiokol - werent they the ones that made the O rings on the space shuttle??
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post #17 of 137 (permalink) Old Mar 17th, 12, 7:29 AM
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Re: Butyl or urethane... AAARG!!!

Quote:
Originally Posted by newmexguy View Post
have seen a lot of urethane hack jobs by individuals who apparently didn't know what they were doing - usually glass that is sunken too low in the opening, with urethane dripping into the interior. Thiokol - werent they the ones that made the O rings on the space shuttle??
What's your point? Butchers are in every business. People should verify the competence of shops who install their glass. And they should also research glass installation themselves. Research generally ends for most when "Heresay Bob" at the cruise night or a forum says butyl was used. Many did not even know GM used a dam. Like it or not, a person is usually responsible for everything that happens to them. As seen in this thread, there are shops who have the knowledge and do excellent work.
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post #18 of 137 (permalink) Old Mar 17th, 12, 4:07 PM
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Re: Butyl or urethane... AAARG!!!

I didn't know you could still get the dams anymore,used to see them alot back in the 90's.I do my own glass and it works fine.The reason for the triangular bead is it stops air pockets and it helps set your height.The reason I don't use the dam is there are now very high viscosity urethanes http://www.dowautomotive.com/product...eal/u418hv.htm that make the damn obsolete.
As long as you have someone to help you place the glass in the opening after you test fit everything dry it is quite simple.I put the urethane on the pinch weld instead of the glass.Once it is in place you can then install the moldings and give a gentle push if needed to set the height,that is the beaty of the HV urethane with a triangular bead it will be slightly higher than needed.
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post #19 of 137 (permalink) Old Mar 19th, 12, 1:12 AM Thread Starter
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Re: Butyl or urethane... AAARG!!!

So as far as the Foam Dam tape goes, which width/height is correct for a 70?
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post #20 of 137 (permalink) Old Mar 19th, 12, 7:23 PM
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Re: Butyl or urethane... AAARG!!!

8mm is about as big as it comes. We are talking foam dam tapes for setting with urethane. Check out Marcy Tapes. Butyl tape is evil....

Steve O.

P.S. Raven1 has all the right reasons....
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post #21 of 137 (permalink) Old May 19th, 12, 7:14 PM
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Re: Butyl or urethane... AAARG!!!

I love using butyl tape - It encourages me to vacuum out my car a lot more often thanks to the water leaks it allows. :-)

Seriously, section 3-2 of my Fisher Body manual clearly outlines the factory specified windshield replacement procedure - and it's a "by hand executed" carbon copy of the assembly line mechanical process outlined by Scott's previous post, quoting Mr. Hinckley.

Now Fisher Body doesn't CALL the window setting adhesive "urethane", but it obviously ISN'T butyl - the FB specified adhesive comes in a tube.

There are two possible pinchweld primers they mention. The cured paint version and the fresh paint version to be used "after fresh collision repairs", quoting the manual again.

Fisher folks are quite adamant that oil based solvents (e.g. kerosene, turpentine, et al) are NOT to be used to clean and prep the glass, as they will (again quoting Fisher Body) "interfere with the adhesion of the adhesive."

Denatured alcohol would probably be a good choice.

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post #22 of 137 (permalink) Old May 29th, 12, 3:24 PM
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Re: Butyl or urethane... AAARG!!!

Quote:
Originally Posted by Dave-1970 View Post
I feel like I have read it all when it comes to butyl tape versus urethane... My glass guy is good, though I don't trust him like I trust myself. I meticulously test fit, measure. and plan before I do anything. He just slaps glass in its place as quick as he can and then on to the next job... My biggest concerns with the urethane is the difficulty of cutting the glass out if job was done wrong, or windshield cracks and needs to be replaced in the future, urethane ooozing onto places it doesn't belong... Also the set height can affect moulding installation... On the contrary my only concern with the butyl is whether or not it is safe for a windshield? Never heard of a windshield dislodging from hard braking or a wreck??? Spent 3 years building this beast, any input is greatly appreciated!!!
I used the butyl tape for my rear window ('70) and was going to use the same thing for the front windshield but two things: 1. if it ain't broke don't fix it. It's not leaking so I left it alone.
2. It looks like it was originally set in the car with butyl tape . If not, then someone ran a very smooth bead of whatever GM used at the time, and its still holding up very well.

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post #23 of 137 (permalink) Old May 29th, 12, 5:02 PM
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Re: Butyl or urethane... AAARG!!!

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Originally Posted by tom6870 View Post
I used the butyl tape for my rear window ('70) and was going to use the same thing for the front windshield but two things: 1. if it ain't broke don't fix it. It's not leaking so I left it alone.
2. It looks like it was originally set in the car with butyl tape . If not, then someone ran a very smooth bead of whatever GM used at the time, and its still holding up very well.

Tom6870
It's not butyl originally. Did you read any of the information in this thread?

The factory used pumpable thiokol with a dam.

That's why it looks neat and smooth.
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post #24 of 137 (permalink) Old May 29th, 12, 5:11 PM
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Re: Butyl or urethane... AAARG!!!

I can ALMOST hear you banging your head on the wall, Scott. You should save a link to one of these discussions and put it in your signature line with something like "Windshield install? READ THIS!!"

I forsee you having to go through this conversation indefinitely....or until your head goes through the wall and gets stuck and you are unable to return to your computer.
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post #25 of 137 (permalink) Old May 29th, 12, 5:54 PM
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Re: Butyl or urethane... AAARG!!!

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Originally Posted by Mike72ss View Post
Without name calling, I followed a respected member, Brain Martin's (MARTINSR) advise.
I really apprecate your kind words. I have had a number of discussions on this subject with Raven1 (sorry I don't remember your real name) and he is right and only trying to protect you guys.

Listen, when I wrote that it was before much training I have including glass setting. So yes, urethane IS what should be used if you want it the best you can possibly do.

But we can split hairs here too. First off, we are driving a car that is MILES from "safe" by todays standards. Tell me about it, I see hits on modern cars where there isn't even so much as a hit of possiblilty of injury to the occupent. The car I drive every day, a 1959 Rambler, I would be HURT bad. So what would urethaning in the windows give me? Nothing that is what. Don't get me wrong, I am not making fun of the proper way to do it like I don't care about life or something. Quite the contrary I value life a LOT, I treasure every day I wake and look up at that beautiful sky. But I also REALLY enjoy driving that 59 Rambler and CHOSE not to drive a boring late model car, why, because life is too damn short.

If you are ever in an accident in a 1968 Chevelle where your butyl tape window comes out, you are SCREWED and that window coming out isn't going to make one hill of poop difference.

Now, this goes beyond what "glue" to use. How about prepairing the pinch weld for the window? If you havn't epoxy primed the pinch weld over BARE METAL (no bondo, no seam sealer, NOTHING) and then glued the window to that epoxy primer, you are going against all guidelines to mounting the glass anyway. If you are bonding your windshield to a basecoat clear coat paint, you might as well glue it in with Elmers. The strength of that bc/cc paint is about as good as a paper clip in relation to the urethane adhesive.

This is a personal decision just as driving that old death trap is. If you want it RIGHT, if you want it the best you possibly can do it. And I can certianly see why any of us would want that, you will epoxy prime over bare metal and then urethane that windshield in just as all the glass professionals say.

It is STILL the right thing to do be damned our personal opinion on what chances we are willing to take. But it is as simple as that, a choice.

I have the windshield in my Gran Sport on butyl, I did it myself and I made the choice that this was the best thing to do for ME. This was about 10 years ago now. If I were to do it today, I would probably set it in urethane.

It's like the epoxy primer before bondo debate, it will go on and on and on and on.

Brian

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post #26 of 137 (permalink) Old May 29th, 12, 6:33 PM
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Re: Butyl or urethane... AAARG!!!

I'm having glass installed in about 2 weeks so this thread is of high interest to me. A friend who has owned quite a few chevelles has recommended me to a local glass guy. I'll have to ask him if which he uses.

It sounds like I need to remove all the paint from the window channels for best adhesion?

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post #27 of 137 (permalink) Old May 29th, 12, 6:39 PM
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Re: Butyl or urethane... AAARG!!!

Quote:
Originally Posted by bocomo1969 View Post
I'm having glass installed in about 2 weeks so this thread is of high interest to me. A friend who has owned quite a few chevelles has recommended me to a local glass guy. I'll have to ask him if which he uses.

It sounds like I need to remove all the paint from the window channels for best adhesion?
WITHOUT A DOUBT, that is FAR more important than whether you use butyl or urethane, FAR more important.

Brian

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post #28 of 137 (permalink) Old May 29th, 12, 8:06 PM
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Re: Butyl or urethane... AAARG!!!

Quote:
Originally Posted by Beaux View Post
I can ALMOST hear you banging your head on the wall, Scott. You should save a link to one of these discussions and put it in your signature line with something like "Windshield install? READ THIS!!"

I forsee you having to go through this conversation indefinitely....or until your head goes through the wall and gets stuck and you are unable to return to your computer.
Funny. One of the reasons I post it is because so many think butyl was used originally. One reason is when glass got replaced that's what many used. Another is some believe everything they hear. The safety or glass retention properties is another part of the topic. It's a no brainer these cars can't take a hit like a new car; and urethane or not you might be dead anyway.

Martin's urethane installation advice is sound and should be followed.

Not all glass guys know what they are doing. We just assume they do. I know glass shops who put urethane over existing paint, fresh or old.
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post #29 of 137 (permalink) Old May 29th, 12, 10:13 PM
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Re: Butyl or urethane... AAARG!!!

And also on that choice I am talking about, let's make it perfectly clear that the glass in a 68 Chevelle is NOT a "structural" part of the car like the glass in a 2012 Camaro. It's a full frame car not a uni-body and there is nothing structural about it.

It is simply going along for the ride, it is not designed into the structure like glass is today in uni-bodies.

And by the way I am probably the only person you may ever know who watched a guy fly thru a windshield right in front of me, I wasn't more than 50 feet away. He actually didn't fly "thru" the windshield glass, he flew thru the windshield opening WITH the glass. I was pumping gas and heard a skid spun my head to see an old ice cream truck hit the rear of a 75ish Chrysler New Yorker. The windshield in the truck was a gasket type, like most were up until the mid sixties (the 63 Riv and Corvette were the first GM cars to have glued in windshields) and without a doubt, just along for the ride.
Thank goodness this guy had a glass that popped out like it did, he wasn't wearing seat belts and he flew like superman hitting the glass and pushing it out. He flew over the trucks hood hitting the back of the Chryslers trunk lid, with the windshield actually hitting the roof of the Chrysler. If it had been a urethaned in glass he would have been hurt MUCH worse I am thinking.

Brian

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post #30 of 137 (permalink) Old May 30th, 12, 9:30 AM
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Re: Butyl or urethane... AAARG!!!

Well, I have PERSONALLY flown through a windshield once, courtesy of a drunk driver, and I can tell you it isn't a lot of fun.

Now, in this thread I find an interesting and vexing discussion point about "removing that paint" (in the window channel, apparently) prior to installing the urethane. Since Raven1/Scott is saying "remove it" I'm taking that idea very seriously...but I must admit that I am confused by the concept.

The correct answers are of high importance to my restoration:

1.) How exactly do you maintain corrosion resistance if you "remove the paint" in the window channel to install the glass?
2.) IF you remove the corrosion protection of paint, how do you decide and maintain a clean boundary line where the paint removal ceases?



On my particular restoration, I meticulously sandblasted all the channel surfaces down to bare metal (and I mean REALLY bare metal - including full removal of any rust from pockmarks. This was not just a light sandblasting)

My channels were in decent shape. Any small rust pockmarks that were suspect thickness were filled by welding, brazing, or leading, (really) depending on the area.

After all metallic repairs were made smooth, the entire thing was glass beaded again, to ensure a clean, flux-free surface.

Then the glass beaded metal was thoroughly cleaned again and conversion coated with phosphoric acid conversion coating

The channels were then gently heated to drive out any residual moisture

I followed this prep work up with a carefully installed coat of an epoxy primer in the entire channel.

I had intended to apply the urethane directly to the epoxy protected channels (no topcoating overspray allowed in the window channels). Now, you're telling me to go BACK to "bare metal" in that channel, apparently so that urethane will "stick". I'm willing to do what's right, but REALLY? Urethane won't adhere to properly applied epoxy primer? SERIOUSLY?

Given the many and notorious failures of the original GM system, which has resulted in the well deserved reputation for leaky A body glass, do I really want to remove my last line of corrosion protection in that channel on the hope that I'll get a little better adhesion of the urethane to bare metal, vs. urethane to epoxy primer?

Again, not looking for a fight here - looking for honest explanation of why urethane won't stick to epoxy primer, and also for opinions of the relative balance of value (better adhesion, vs. loss of corrosion protection to get that adhesion)

Thanks for your opinions!


Keith




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