Windshield and backlite replacement has always mystified enthusiasts because it is the wild/weird science of laying laminated and plate glass onto a steel frame hoping it will successfully seal out the weather and look good. For ages, windshields and backlites were secured with a continuous rubber seal and non-curing gooey black sealant. In the 1960s, GM went to glue-in windshields and backlites that not only didn’t leak but also stayed secured to the body in a collision in the interest of safety. Windshields and backlites held in with a rubber gasket had a tendency to pop out in collisions, placing occupants in great danger.
When you’re installing glue-in glass, follow the manufacturer’s instructions to the letter. 3M makes great auto body prep products, which are available through a lot of sources, such as Summit Racing Equipment. We’re working with 3M’s Fast Cure Auto Glass Urethane (PN 08690), which is a fast-curing urethane windshield adhesive and sealer designed for use with glue-in windshields and backlites.
We’ve found that 3M Fast Cure Auto Glass Urethane is a single-stage moisture curing urethane providing rapid strength build-up. You don’t have to wait for it to cure because it is a high-strength adhesive designed for use in full cutout installations without damming materials. It provides the bonding strength required for the installation of vehicle windshields, backlites, and sidelites. When fully cured, the 3M glass urethane meets the OEM strength requirements specified by Chevrolet.
We’re at Hot Rods by Dean in Phoenix where we’re going to show you the basics of how to install glue-in windshields and backlites on a first-gen Camaro. You must first begin by thoroughly cleaning the contact surfaces and removing all of the old adhesive and any glass fragments. The surfaces must then be primed with the appropriate 3M primer compatible with 3M’s Fast Cure Auto Glass Urethane sealer. The primer seals any scratches at the pinch-weld where the glass sits to prevent rust. Once the primer has cured, make sure the glass contact surfaces are clean. With good surface prep you’re ready for glass installation, which must be methodically performed with close attention to detail. Hot Rods by Dean will show you how. CHP
1. Once you have cleaned all the windshield contact surfaces to where they are hospital clean—including the glass and pinch weld surfaces—carefully install the windshield molding clips. We got ours from Classic Headquarters. The challenge here is to install the clips without scratching the paint. Note where the clip seats against the pinch weld and the tip that secures the stainless trim.
2. Test fit all glass before applying the 3M Fast Cure Auto Glass Urethane sealer. Windshield installation is nearly foolproof because GM provides glass supports at the base of the windshield. This approach beats the socks off of the old rubber seals we used to work with in classic Chevys. It was also a safety issue because rubber gasket windshields and backlites could pop out in accidents. It also took less labor time to install on the assembly line.
3. The backlite installs the same way, with supports (arrows) at the base of the glass, which ensures proper glass placement. Check the fit before laying down the adhesive. The guys at Hot Rods by Dean use masking tape as a good reference line.
4. Hot Rods by Dean uses 3M Fast Cure Auto Glass Urethane sealer because it is very forgiving and cures quickly. Follow 3M’s instructions closely.
5. The sealer/adhesive is applied in conservative amounts because you don’t want the stuff oozing out around the perimeter. Lay down a 1/4- to 3/8-inch bead and, with a helper, lay the glass in. Once the glass is laid in, using the palms of you hands, carefully press the glass into place around the perimeter. Trim away any excess sealer with a razor blade before the sealer has a chance to completely cure.
6. Here you can see the windshield has been carefully pressed into place and is allowed to set up.
7. Classic Headquarters provided us with new stainless windshield molding, which is protected with a blue film. The blue film will be removed during installation.
8. The backlite has been firmly pressed into place and the 3M sealer has been allowed to cure. We’re ready for stainless installation.
9. The stainless trim installation begins at the bottom. Use your palms to carefully press the molding into place. Listen for the click of the trim clip. Make no mistake, this is not easy. You will run into clips and molding that won’t seat together easily. The ease of installation depends upon body construction to begin with, any collision damage not properly repaired, and how much sealer you used. If you used too much, it gets tricky. Press evenly with your palms and do not pound on the molding.
10. You can see how the windshield molding is installed. Bottom molding first, then top, and then sides. Again, press firmly and do not pound.
11. Hot Rods by Dean has done an excellent job of installing the glass and seating the molding. There are no dents in the molding because we haven’t pounded the trim—just pressed the trim into place using open palms. It works.
Photography by Brian Brennan