72 windshield sealer

[Edward M.]

I finally got the windshield out of my 72 coupe, in preparation for some minor frame repair. The windshield came out in peices (naturally), but was no big loss since it was delaminating badly. One interesting thing, it was an orignal GM windshield, dated May of 1971. My car is a May 1972 build date. All of the other glass is dated April of 1972. I also believe that the windshield had been out of this car previously, so I suspect that it was replaced with a used windshield from a 71. Enough about this.

Where can I get the butyl type sealer that was used to seal the windshield header panel. I am talking about the putty like black stuff that is put between the top of the windshield frame and the stainless t-bar trim. The old stuff in mine is hard as a rock.

Fortunately, my windshield frame is in pretty good shape, with just some minor rust issues. I expect that these will clean up OK.

[Dick W.]

Re: 72 windshield sealer

Ed, you should be able to get it a an auto body paint store or some parts houses. It is 3 M Strip Caulk. There is enough in a package to do many windshields. If you have a friend at a body shop, you might be able to bum enough.

[Dick W.]

Re: 72 windshield sealer

Ed, you should be able to get it a an auto body paint store or some parts houses. It is 3 M Strip Caulk. There is enough in a package to do many windshields. If you have a friend at a body shop, you might be able to bum enough.

[Chuck S.]

Re: 72 windshield sealer

Ed, your windshield may have been original. Sometime ago, OEM glass told me that dates on glass can be up to a year before your build date. The windshield could have been removed and replaced, but I wouldn't automatically assume it wasn't the original.

I'm not sure the sealer between the frame and the T-top trim was butyl...the modern stuff used for installing windshields is butyl, but it's an adhesive from hell. The closest substitute for the frame/trim sealant today is 3M "Strip-Calk" at auto paint stores. Does your frame also have a foam rubber strip seal backing up the black sealing material?

[Chuck S.]

Re: 72 windshield sealer

Ed, your windshield may have been original. Sometime ago, OEM glass told me that dates on glass can be up to a year before your build date. The windshield could have been removed and replaced, but I wouldn't automatically assume it wasn't the original.

I'm not sure the sealer between the frame and the T-top trim was butyl...the modern stuff used for installing windshields is butyl, but it's an adhesive from hell. The closest substitute for the frame/trim sealant today is 3M "Strip-Calk" at auto paint stores. Does your frame also have a foam rubber strip seal backing up the black sealing material?

[Edward M.]

Re: 72 windshield sealer

Thanks for the info guys, I'll check my local body shop. I'm pretty sure the windshield in my car had been replaced in it's past. The way it was sealed in the car leads me to believe this. I did keep the date code part of the windshield for future reference. My car did not have any foam rubber backing up the black sealing material.

Now the question comes up, what do I do about a date code on the replacement windshield glass. Do I date it like the windshield that came out of the car (May, 1971) or like the rest of the glass in the car (April, 1972)?

[Edward M.]

Re: 72 windshield sealer

Thanks for the info guys, I'll check my local body shop. I'm pretty sure the windshield in my car had been replaced in it's past. The way it was sealed in the car leads me to believe this. I did keep the date code part of the windshield for future reference. My car did not have any foam rubber backing up the black sealing material.

Now the question comes up, what do I do about a date code on the replacement windshield glass. Do I date it like the windshield that came out of the car (May, 1971) or like the rest of the glass in the car (April, 1972)?

[Chuck S.]

Re: 72 windshield sealer

If you go to OEM Glass, they will be able to give you some guidance on dating. Personally, I would have them use anything OTHER than April, 72. Also, there is no point in straining credibility with inexperienced judges by using something as early as May, 71.

Glass dating begins to look contrived to perfection with all the same dates...use anything after November, 71...maybe January or February. Frankly, I'm surprised the rest of your glass is dated all the same, and that close to your build date. Doesn't mean it's not original...assembly line must have been running hot and tight.

[Chuck S.]

Re: 72 windshield sealer

If you go to OEM Glass, they will be able to give you some guidance on dating. Personally, I would have them use anything OTHER than April, 72. Also, there is no point in straining credibility with inexperienced judges by using something as early as May, 71.

Glass dating begins to look contrived to perfection with all the same dates...use anything after November, 71...maybe January or February. Frankly, I'm surprised the rest of your glass is dated all the same, and that close to your build date. Doesn't mean it's not original...assembly line must have been running hot and tight.

[Jim T.]

Re: 72 windshield sealer

The 3-M strip caulk can also be painted and will not harden like the original sealant. When I caulked my 70 I painted it to keep it from attracting dirt. 3-M strip caulk is paintable.

[Jim T.]

Re: 72 windshield sealer

The 3-M strip caulk can also be painted and will not harden like the original sealant. When I caulked my 70 I painted it to keep it from attracting dirt. 3-M strip caulk is paintable.

[Roger S.]

Re: 72 windshield sealer

Our local Advance Auto store has the 3M windshield sealant. It is the rope type material, black in color and I believe it is 3/8" thick. Cost is just over $11.
Roger

[Roger S.]

Re: 72 windshield sealer

Our local Advance Auto store has the 3M windshield sealant. It is the rope type material, black in color and I believe it is 3/8" thick. Cost is just over $11.
Roger

[John H.]

Re: 72 windshield sealer

GM never used the butyl tape for factory-installed fixed glass, although many glass shops used to use it instead of the correct adhesive (fixed glass installed with butyl tape won't pass FMVSS 201/208 tests). C3 Corvette windshields (and 1964-up backlites) were originally installed with Thiokol adhesive, which later changed to "Improved 2-Part Thiokol", and later still to urethane, which has been the OEM industry standard for many years (with a Silane primer for the body flange and a different primer for the glass - neither Thiokol nor urethane will adhere to topcoat paint or glass without special primers).

[John H.]

Re: 72 windshield sealer

GM never used the butyl tape for factory-installed fixed glass, although many glass shops used to use it instead of the correct adhesive (fixed glass installed with butyl tape won't pass FMVSS 201/208 tests). C3 Corvette windshields (and 1964-up backlites) were originally installed with Thiokol adhesive, which later changed to "Improved 2-Part Thiokol", and later still to urethane, which has been the OEM industry standard for many years (with a Silane primer for the body flange and a different primer for the glass - neither Thiokol nor urethane will adhere to topcoat paint or glass without special primers).