C2 Coupe rear glass install

[Jeremy Hedges]

What is the best sealant to use on installing a coupe rear glass? How and what kind. Any help would be appreciated.

[Mike M.]

Re: C2 Coupe rear glass install

go to autobody supply house and ask for the butyl tape similar to that which was used to install the rear glass in your midyear coupe originally, ,good luck, mike

[John H.]

Re: C2 Coupe rear glass install

The factory rear glass-to-body adhesive was 2-part Thiokol that was mixed at the dispensing tip, applied to the (primed) glass as a triangular-shaped bead, and the glass was then placed in the opening - took about 30 minutes to set up. Butyl tape was never used in production by GM, although it was popular with glass replacement shops in those days because it was quicker and more economical than using the dual-cartridge mixing dispenser of the correct sealant. Thiokol was eventually replaced in production by urethane in later years, which is what you'll find in glass shops these days. Urethane will work just fine - be sure and use the specified primers on the glass AND on the body flanges so the urethane will bond to both materials.

[Mike M.]

Re: C2 Coupe rear glass install

john: i thought the factory used a tape(butyl or whatever was the hot lick in 64) because when i removed the rear glass from my 64 coupe in about 1970,the bead was perfectly uniform the 360 degrees @ window opening(ie uniform in thickness and width).hard to imagine any tool dispensing a uniform bead, especially if a human hand controlled the dispensing tool. perhaps someone had the glass out of my64 coupe between 64 and 70. however, the old girl still has what i believe(based on LOF date code) its original rear glass.

[Mike McKown]

Question on the urethene

Can you get the glass back out without breaking it? My experience with urethene is that you will break the glass to get it out. Just wondering.

[John H.]

Re: Question on the urethene

Mike -

For windshield glass replacement in the plant in recent years, we used a hand cable-pulled windshield knife and an air vibrator knife in the tough spots to cut them out; broke about half of them getting them out. Windshields these days are a lot thinner than they were in the 60's.

[John H.]

Re: C2 Coupe rear glass install

Mike -

My guys supplied the Thiokol dispensing systems, guide-tip nozzles, etc. to St. Louis; the glass was mounted (inverted) with suction cups on a rotating turntable driven by an electric motor (for constant speed), where it was cleaned, silane-primed, then the Thiokol bead was applied by holding the tip essentially stationary against the edge of the glass while the glass rotated past the tip. The bead went on as a uniform triangle in cross-section, but compressed into a shallow rectangular shape when the glass was loaded to the body; the cross-section of the cured bead was controlled by the little rubber spacer blocks around the edges.

[Mike McKown]

John: your experience was about the same as mine

except we didn't have the vibrating knife. We broke such a large percentage of them even trying to be careful that we finally gave up and just pushed them out with our feet, and that broke every one of them. We started with butyl tape in the early '80's and you could get the glass out several days later inside the plant just by pushing it out. Then we went to urethene and that was the end of the ballgame.