If you're shopping for a new windshield (the front windshield is the most commonly replaced auto glass) you may be curious about what to expect during the windshield replacement process. So here's what happens at a basic installation. If your windshield is equipped with special features, such as heating elements or a rain sensor, then there may be additional steps:
Before the technician removes your windshield, he will set up his work area to make sure your vehicle is not damaged in the process. He'll outline your windshield with protective tape and place towels on top of the dash and over your hood. He'll also remove your windshield wipers and rear view mirror, and detach and move the cowl (that's the piece at the base of your windshield).
To begin removing your old windshield, the technician first unfastens the molding-the strip of chrome and/or rubber that provides an extra seal between the windshield and the vehicle (older automobiles will likely have molding around the entire windshield, some newer vehicles have less or none). Sometimes the molding can be reused, but often it must be replaced.
Your installer will use a special knife to cut through the urethane adhesive keeping your current windshield in place and push the windshield out of the frame. Since the removal requires brute force, usually the windshield cracks considerably, and if you're watching the replacement, you may be alarmed. Not to worry, it's all part of the process. The technician will store the old windshield glass in his vehicle to be recycled, so you don't have to worry about disposing of it.
After the old glass is out of the frame, the installer will use what's called the “full cut” method to strip the old urethane down as close as possible to the metal frame, allowing the new urethane to bond properly to the frame and windshield. With the old urethane gone, the technician will prime both the frame and new windshield surfaces. This ensures that no contamination occurs-preventing leaks and ensuring a strong bond-so the new windshield meets the same safety standards as the original factory-installed windshield.
Your technician now “dry sets” the windshield, lowering it into place to mark exactly where it will fit, since the windshield shouldn't be moved around once the urethane has been applied. Using a special attachment to a caulking gun-type tool, the installer will then apply the adhesive to the appropriate surfaces. He will carefully place the new windshield into the opening, using the marks he made earlier in the process as guides. When your installer is working with your new windshield, he wears disposable gloves to avoid contaminating the edge of the windshield with his bare hands.
After the windshield has been installed, your installer will then install your molding, cowl, rear view mirror, and windshield wipers. He'll clean up any broken glass or debris in and around your vehicle.
The installation is finished, but your vehicle isn't ready to drive yet. First, the urethane must fully harden, or "cure." The amount of time this takes depends on the kind of urethane used, the temperature, and the humidity. Your installer will calculate a safe "drive-away" time for you.
After your installer is completely finished with the windshield installation, he should have some paperwork for you to sign. If you're not around for the installation, he should leave the paperwork in your car, as well as a tag letting you know when you can drive your car.
You may also notice that one or two of your vehicle's windows have been left open a crack. That's so that if you open or close your door before the urethane has fully cured, the changing air pressure inside the car won't dislodge the windshield.
When properly installed, your auto glass will meet the safety specifications of the original factory-installed windshield.