[Raven1]

Originally Posted by 67shovel

I like to do it myself and have been using buytl tape for forty years. The buytl costs about $10.00 a window, roll it out and set the glass in...about 5 minutes of work. The body by Fisher manual shows how to add urathane to the top and sides of the windshield to insure no leakage. You put a bead of urathane on the top and sides after you've placed the glass and then, w/ a paint stick, you create a flat smooth slope that the water will drain off of instead of hanging around in the voids on the top. I didn't think/know that GM cars of the 60's were using the W/S & B/G as structural components yet.

If you read my previous post you would see that technique was used by GM but they did not use urethane back then, it was thiokol. I used tape decades ago too but since have stopped. My glass company cannot use butyl tape because it's illegal and their liability insurance would not cover it and a lawsuit would result if injuries were sustained due to it's use. I get my windshields intalled for $140 including the glass and they come to my house. It's not worth my time to do them. And when in the collision business the volume of glass replacements dictate cost efficiency by farming it out. My glass data comes directly from John Hinckley who was directly involved in GM engineering.

**The MVSS windshield retention standard became effective in 1967.

**See the Fisher Body Service Manual - the plastic tip on the tube of adhesive is notched to produce a triangular bead 3/16" wide at the base by 3/8" high.

[smoke' em II]

This is what 3M told me about their buytl tape and their pinch weld primer.

Question:

AAD Contact Us

1st. Can 3M Single Step Primer 08682 be used with 3M Window-Welt Round Ribbon Sealer 08611 for a better seal/ bond?

2nd. Can 3M Single Step Primer 08682 be used as the only primer on "bare metal" for setting the rear glass, or should some sort of automotive etching primer be used on the sand blasted bare metal window channel first?



ANSWER:

Thank you for contacting 3M.

The 3M(TM) Single Step Primer is not compatible with the 3M(TM) Window-Weld Ribbon Sealer. We no longer have no primer for use with the 3M(TM) Window-Weld Ribbon Sealer.

The 3M(TM) Single Step Primer must be used on the glass to protect the windshield urethane from UV radiation. It is also used on the pinch weld wherever small areas of metal have been exposed during the removal of the original glass. The pinch weld should be primed with a two part primer, not an etching primer.

Regards,

Thomas
3M Automotive Aftermarket Division
www.3m.com/automotive
1-877-666-2277

I was planing to grind the pinch weld area to bare metal, then coat with POR-15, then apply 3M pinch weld primer to glass and pinch weld, then apply 3M Window-Welt Round Ribbon Sealer (5/16") to glass, then install glass into the car.
Onced the glass was in, install molding clips, and then go around the perimiter of the rear window with 3M Window-Weld urethane glue, just to make sure???

[Mike72ss]

Lance, this is the butyl primer I used:


http://www.crlaurence.com/crlapps/sh...&ModelID=19983

Mike

[JNorton]

Hmmm. This post has me reconsidering the way I've done windshields in the past. I've used the butyl tape and urethane around the top and sides of the glass. I've even seen a glass guy do it the same was on a Cutlass I had.

[cromedss]

I would agree urethane is structurally stronger and better. I will have to tell you though after removing my front and back glass that was butyl taped in I have no worries about safety. I think you would stand a better chance of flying through the firewall and engine block before your windshield would fly out. When the time comes I will probably do what another has suggested and use buytl tape followed by urethane around the edges.

[1966_L78]

Originally Posted by Raven1

That's because the guys doing it were incompetent. As stated, I/we have been using the same glass shop for decades.

You are lucky... Out of the past 4-5 windshields I have had installed, only one shop did a decent job...

By "decent" I mean NOT having urethane around/against the glass clips and having the level of the glass correct...

Seems most of the techs aren't used to setting glass in cars with trim clips, Most techs just want to fill the area with U caulk...
and once the urethane has set up, the clips don't flex well, making trim installation (and especially removal) very difficult...
The latest shop was the first to tell me that Butyl was illegal for windshields... So I made sure that they wouldn't just flood the entire channel with caulk...

[Motorvation]

"Back filling" the pinchweld is like wearing suspenders and a belt at the same time. You got to have quality urethane and be ready to install the mouldings once you set the glass. It's the "body"/ viscosity that holds the w/s or b/g up. If it's oozing out to the clips and the glass is pushing it out then the urethane is NFG for the application. I don't mean to be an azzhole, but I would have thought you West Coast guys would have glass installation to a state over-regulated, no hit or miss deal program. Look for a shop that is AGRSS(Auto Glass Safety Standards) compliant.

Steve O.

[Motorvation]

Originally Posted by JNorton

Hmmm. This post has me reconsidering the way I've done windshields in the past. I've used the butyl tape and urethane around the top and sides of the glass. I've even seen a glass guy do it the same was on a Cutlass I had.

I'll bet he worked for a chain glass company.....They work volume, don't care about your safety.......Your Cutlass probably had rust growing in a year and a leak in less than two......

Steve O.

[Hunter]

I just had the front and rear done on my 69 by an old timer from a local glass shop.

He does not do many of these because he never knows what he is getting into, after seeing that the car was just painted, all the clip pins were sound and I was using the factory trim (he would not do the job with after market) he agreed.

After he primed the glass he laid a cone type bead of sealer on the glass and set in in place. he explained that he does this so the trim would set the glass height.

It was perfect trim to body and trim to glass fit.

Best $190 bucks I ever spent as it looks perfect and I know will never leak.

[JNorton]

Originally Posted by Motorvation

I'll bet he worked for a chain glass company.....They work volume, don't care about your safety.......Your Cutlass probably had rust growing in a year and a leak in less than two......

Steve O.

It was Guardian Glass, if I remember correctly. This was back in the mid 80s. The job held up fine for the 4 or so years that I owned the car after that.

[MikeMalibu]

I recently had the front and back glass installed and agonized over using butyl or urethane based on just the controversy discussed in this thread. A local restoration shop recommended a glass installer that could do either method on Chevelles. I talked at length with him and looked at several cars he had done with urethane. He said he would do either method for the same price, and said that the butyl tape method was quicker and easier for him. He said the butyl remains tacky and melts in our hot summers, whereas the urethane stays firm. His recommendation was urethane caulk because it lasts longer and gives a better seal in his experience. Because I was particular about not seeing the squeeze out, he used a foam dam at the package tray and at the dash (the dash pad hides most of the bead and who looks back at the package tray anyway?). He used a black glossy primer on the glass (about 1 inch in height) that hid the caulk and pinch welds from view, and the primer is mostly covered by the trim. In addition to the rubber blocks at the bottom holding the glass up, he added some small blocks as "spacers" around the perimeter. He attached the SS trim pieces immediatly after setting the glass. The glass fits close to the trim (you can't drag paper under the trim except at the corners where the glass curve doesn't follow the body and trim). I'm pleased with the way it looks and would use urethane caulk again. Just my experience FYI.

[figbash]

According to the National Highway Safety Administration, butyl tape and urethane adhesive are functionally equivalent. To quote an article published by them in 1985:

"Butyl tape and polyurethane sealant--two alternative adhesive bonding techniques--provide approximately equal windshield retention in crashes."

Having removed a number of windshields held in with butyl rubber, I would tend to agree.

http://www.nhtsa.dot.gov/Cars/rules/...te/806693.html

Tom

[Motorvation]

Originally Posted by figbash

"Butyl tape and polyurethane sealant--two alternative adhesive bonding techniques--provide approximately equal windshield retention in crashes."

Having removed a number of windshields held in with butyl rubber, I would tend to agree.

http://www.nhtsa.dot.gov/Cars/rules/...te/806693.html

Tom

There's no way I'll believe that! Somebody at that 1985 test was smokin dope.....Try cutting urethane with the same tool you cut that butyl with, aint gonna happen.....

Steve O.

[figbash]

Originally Posted by Motorvation

Try cutting urethane with the same tool you cut that butyl with, aint gonna happen.....

Steve O.

Even if the urethane is stronger than butyl rubber, who cares? As long as both are strong enough to do the job. I prefer the butyl rubber because it's easier to work with, more readily available and cheaper than urethane.

Tom