Body / Glass: Butyl vulcanizing tape

[tluz]

hi, Guys,

I am putting the back glass and windshield into the Avanti. The shop manual calls for "butyl vulcanizing tape." What is it and where can I get it? The 65-year-old owner of our local NAPA store has no idea what it is. Googling it does not yield a very useful answer. Better yet, what products can I use instead? Since this stuff is not generally available, I have to believe that auto glass places have an acceptable substitute.

With respect to the windshield, the manual calls for "soft sealing compound." What does this mean? Can i use silicone sealer? And why is the installation of the back glass different from that of the windshield? All very curious.

Thanks for the help.

Tom

[kurtruk]

NEVER use silicone. It has no adhesive strength, attracts dirt, and a bunch more bad qualities when it comes to auto glass. Talk to a professional auto glass installer and tell him what you are doing. Hopefully they'll lead you in the right direction.

[wcarroll@outrageous.net]

What you want is 3M Strip-Caulk. I've sourced it from Napa on a few occasions.

http://3mcollision.com/3m-strip-calk-08578-black.html

[Dan Timberlake]

I have no idea what the original installation method was, but NAPA and body shops sell butyl tape in varying thicknesses for installing glass in GM cars from the 60s, and probably lots of others too. It's the installation where the old glass is removed by actually cutting the old adhesive with a wire or special cutter. The "tape" ( ~5/16 inch thick sticky conformable rope" is positioned in a channel surrounding window opening, and glass just kind of sits on it, and compresses it. Rubber blocks are needed to keep the glass from oozing downward in the overiszed opening.

http://www.martinsenour-autopaint.com/media/pds/english/9512.pdf

[mmagic]

My bad... it's an Avanti. My withdrawn comment applied Champ.

[tbirdtbird]

black butyl tape was used prolly by most every manufacturer back in the day. It is still available in auto glass shops, but looks easier to use than it is. Window urethane is avail from NAPA and most others, comes in a cartridge to use with a caulking gun. Works well, seals well, but can be messy, glove up and don't get it where u don't want it. And if u want to get the glass out later you will either have to heat the cured urethane with a torch or break the glass and dig the urethane out, or use a knife or wire if you are lucky. Strongly suggest you leave glass installs to the pros unless it is the kind you install in one of those old-school heavy rubber gaskets.

[bezhawk]

DO NOT USE URETHANE!!!!!!! Ok, I'm done shouting, but if you have ever tried to remove a gasketed glass that has been urethaned in place, then you'll know what I'm saying.
Use NON-hardening windsheild and bedding compound (3M name).
In an Avanti, you will either break the glass, or break the fiberglass gasket fence (pinch weld), if you use urethane, and try to remove it at a later time.

[tluz]

Many thanks, guys. All useful comments. Even though I'm a rank amateur, I'm going to take a run at this because my intention from the beginning was to take the car apart myself and put it back together myself. If I fail grotesquely I'll cheat and use a professional.

[R2Andrea]

DO NOT USE silicone, urethane or the butyl setting tape. These all will cause various problems that you don't want to get involved with. Use the 3M strip caulk on the body and use the 3M Glazing and Bedding Compound between the gasket and body. Seal between the glass and gasket with either the Bedding and Glazing Compound ( OK) or CRL 1716 Windshield and Repair Sealant (Best). You might be able to get the 3M products through a local auto parts shop but you'll have to either go to an auto glass shop or order the CRL 1719 sealer direct from the C R Laurence Co. It is acceptable to seal the glass to the gasket with silicone but use non acid cure silicone. NEVER use silicone anywhere but between the glass and rubber. If you go with a professional installer make sure they have lots of experience doing old cars. Those guys are getting hard to find.

A word to the wise from 25 years as an NGA Master Installer.

[tluz]

Thanks, Andy,

OK, I'm pretty confused now.

I got the 3M strip caulk and used it as directed in the shop manual between the back glass and rubber. After that I saw your post and wanted to make sure i understand what you are telling me. Are you saying that the strip caulk should not be used between glass and rubber? It seems to have stuck pretty well and sealed all the way around. If it's acceptable to do it the shop manual way, is there some other sealant that has to be used in addition? If not, what problems are likely from following the shop manual's instructions?

I have 3M bedding and glazing compound also, which the shop manual says should be put between the windshield gasket and the body, but you say should go between the rubber and the glass. So your instructions and the shop manual instructions are the reverse of each other. I guess I don't understand what these various compounds are supposed to do and how they differ from each other. Any further help you can offer would be appreciated.

Tom

[R2Andrea]

There are some assumptions made with my above post: A) that you are using the original back glass and B) that you are using one of the (non OEM) replacement gaskets. IF you can find the butyl strip caulk in the specified dimensions and IF you are using a gasket with the original inside dimensions then that method (per the shop manual) should work the best. If you are using the aftermarket gaskets then you'll have a problem. The aftermarket gaskets are made from an extrusion which has a glass bed which is narrower in width and makes it very difficult to fit around the glass and keep the stainless trim in its proper place. Adding the butyl strip takes up even more space and amplifies the problem. My choices for sealing between the glass and gasket would be: 1a) CRL 1719 Windshield and Repair Sealant, 1b) the butyl tape, but only if it is an OEM glass/OEM Gasket combination, 2) non-acid cure silicone, and 3) the bedding and glazing compound. These are all (except 1b) squirted between the glass and gasket after the assembly is installed in the opening and the body to gasket sealer mess is cleaned up. The strip caulk is used to fill any large gaps between the body/pinchweld area and the gasket, and is the method outlined in the windshield installation instructions in the shop manual. I realize now that I should have clarified this in my first post. The CRL 1719 sealer is still the prefered method of sealing the glass to the gasket in all cases EXCEPT an Avanti B/G in the case of 1b. Be advised that the butyl stripping is a one shot deal. You must get it in the proper location the first time because it sticks immediately. The Bedding and Glazing Compound is real messy. I tape off the interior trim and exterior painted surfaces with layers of 2"-3" masking tape and masking paper to keep cleanup problems to a minimum.

[R2Andrea]

Thanks, Andy,

OK, I'm pretty confused now.



I guess I don't understand what these various compounds are supposed to do and how they differ from each other. Any further help you can offer would be appreciated.

Tom

1) The butyl sealing tape is a non hardening butyl sealer. It is used to seal between the glass and gasket on the B/G and sticks the gasket to the glass to keep it from shifting during installation.
2) The 3M strip caulk is a (more or less) non hardening caulk used to fill large gaps between the body/pinchweld and gasket. The stuff Studebaker used is the thick, off white stuff found between the opening and gasket on an original installation.
3) 3M Glazing and Bedding Compound is a non hardening sealer used to seal between the gasket and opening. It comes in a caulking tube and looks like a thick grease (and is about as messy).
4) CRL 1719 Windshield and Repair Sealer is a thick liquid sealer that hardens to a flexible rubber like consistancy and is used to seal between the glass and gasket. It works best in all situations other than an Avanti B/G with OEM glass and OEM Gasket. In this case it's only drawback is that it doesn't keep the gasket adhired to the glass during installation.
I hope this clarifies things.

PS You'll find having a "hook tool" to be pretty much indespensible for glass installation. It's used to help work the gasket over the pinchweld. My all time favorite is the MAC Tools SP-29A cotter pin puller. Just grind the sharp tip to a nice radius. You could also make yourself one by grinding the flutes off of a long phillips screwdriver, heating it with a torch and bending it into a nice hook at the end.

[Rerun]

R2Andy's advice about covers it. I installed one once in my '63, and it was a bit of an adventure. I would recommend that you have two people outside and one inside for the actual installation.

For the anal among us, find the center of the bottom of the glass and mark it with a Sharpie. Align the butt seam of the gasket with this center mark when you install it. If you mark the center of the body (on a piece of masking tape) too, it helps when initially setting the glass down, so you don't have to try to slide it sideways when you get to setting the sides.

[tluz]

I got the glazing and bedding compound and installed the windshield today. "Messy" is an understatement, but that's not the main issue. The gasket I got from SI does not seem to fit. I tried to align it twice, and both times I was left with pretty big gaps (about a half-inch) on one side and both top corners. The glass fit in well enough and the trim is in the channel properly. The gasket went over the pinch weld and overlapping vinyl, but seems to not have enough material to fill the space in the front.

Have others encountered this problem? What should I do about it? Stuff the gaps with more bedding compound? Try to re-set the windshield? Any advice accepted.

Thanks,

Tom

[mmagic]

My SI gasket fit great. It was flexible enough that with bedding compound in the glass channel I easily nudged it to position. I inserted the trim then held it in place with duct tape for several days until I got to actually install it. Agree with messy my first 4 tries! But, once I put bedding compound in front of the pinch-weld instead of on it and positioned the windshield directly in line with the target location instead of over the bottom as per the book I could have done it with my Sunday clothes on.