Installing a Windshield or Back Glass


Installing a Windshield or Back Glass



The last article was about removing the glass and making a seal cutting tool. This article will deal with installing the windshield and rear glass. First make sure the pinch-weld area is absolutely clean, straight and all rust repaired or surface rust treated with POR-15 or a similar product. The area should be primed and painted body color if repaired. BTW I’ve never had a problem painting over POR. Next make sure you have the proper thickness 3M sealing ribbon for your glass. If you’re reinstalling an original (thick) windshield or ANY rear glass, new or original (same thickness), use 5/16in thick ribbon. If installing a replacement windshield (thinner than original), use 3/8in ribbon. It’s available from body shop supply houses and some Chevelle parts houses such as Year One.

The thickness of the ribbon determines the proper spacing of the glass out from the metal in relation to the trim studs to allow for correct trim installation. For instance if you use 3/8in thick ribbon on a rear glass you’ll have a really hard time getting the trim to snap in place (ask me how I know). It’s also a good idea to get at least one of the large suction cups made for body work. They’re available cheap at discount auto parts stores.

With your paint protected with masking tape and blankets as described in the previous issue, trial fit the glass in the opening without the sealing ribbon. That’s important. Use the rubber spacer blocks in the seal kit on the bottom of the glass to properly space it up from the bottom of the opening. You can turn the blocks for different spacing thicknesses. Center the glass in the opening precisely. Then take a piece of masking tape and put it on the center bottom of the glass so it runs from the glass onto the body. With an ink pen draw a line in the center of the tape on the glass running onto the body. Then cut the tape between the glass and body with a knife. Now you have centering alignment marks for the final install.

Peel the backing off as you install the ribbon on either the edge of the glass (interior side) or at the edge of the pinch weld. DO NOT attempt to pull up the ribbon after it’s stuck or you’ll stretch it and make a thin spot which cause a leak. Be careful not to allow anything to touch the ribbon or it will stick. Make the end seam of the ribbon on the side or top of the opening or glass and butt the ends by overlapping one on top of the other then cutting the top layer even with the starting end.

Stick the suction cup on the center top of the glass and place the bottom spacer blocks in position. With one person at each end of the glass, carefully lift the bottom edge only into the opening with the glass angled out so the ribbon doesn’t stick to anything yet. Center the glass by lining up the ink alignment marks before gently tilting it forward as far as your fingers will allow. Then use the suction cup to finish tilting it into place. Go around the edge with your fingers gently pushing the glass into the seal with a steady even pressure. If you have any stretched thin spots in the sealer that won’t seal, push a small piece of leftover ribbon into the seal from the inside with a blunt instrument as required to get a seal as viewed from the outside of the glass. Use wax paper over the blunt instrument to keep the seal from sticking to it. Reinstall the interior and exterior trim and that’s it. It’s a good idea to get all new trim clips and it’s the perfect time to get exterior trim restored or replace it.