One of the more frustrating aspects of vintage Mustang ownership and restoration is leaking windshields. It's frustrating because no one wants to see their carpet-or feet-soaking wet. Classic Mustangs used rubber gaskets for windshields and rear glass through 1968. Beginning in 1969, Ford started gluing in the windshields, yet stayed with rubber-gasket backlights through 1973. Glued-in windshields have been a blessing because, unless you're really careless, they will not leak. Rubber-gasket installations take a lot of practice to keep them from leaking. Rare is the rubber-gasket windshield that doesn't. If your toes and carpet are wet, you're in good company because a lot of us wrestle with the same problem.
We're going to explain how classic Mustang windshields and backlights are installed, and how to prevent them from leaking. Because this is an inexact science, we offer no guarantees. Sometimes, you can painstakingly install a windshield, thinking you've covered all the bases, and still wind up with water on your floor or in your trunk. We hope this useful information will lead you to a dry interior.
We invited Antique Auto Glass to visit our shop and install a windshield. These guys use a different approach than the Ford shop manual instructions, which tell us to run sealer around the inside pocket of the gasket as well as the outside pocket, then install the gasket on the windshield. Antique Auto Glass follows the Ford shop manual's instructions to apply sealer to both pockets before installation. Then, they install the rubber gasket on the body first. Once the gasket is installed on the body, they follow with the windshield. Instead of using the rope trick we've all been taught, Antique Auto Glass' Frank Doha lays the glass on the rubber and works the rubber over the glass with a tool.