How to Replace Your Automobile Windshield

Monsoon24

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posted on 17 years ago — updated on 1 second ago

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We often take our windshield for granted. It seems to always be there when we are driving, and for the most part doesn't cause any trouble. It is, however, very important that your windshield be in good repair. If it does need replaced, it has to be done correctly to ensure the safety of yourself and your passengers.

Quick Steps

Removing the Old Windshield

Remove any plastic moldings from around the windshield. Take care to remove any clips holding the molding in place properly. These clips release many different ways (i.e. pull straight out, remove the middle first, push in from either side, etc.) but damaging them will mean that they have to be replaced. They can range from very cheap, to relatively expensive, and some of them are hard to find.

Analyze the best angle to separate the windshield from the pinch-weld. The pinch-weld is an area at the front of the car where different metal components are welded together. This provides structure and forms a frame for the windshield. In order to remove the windshield you must cut it away from the pinch-weld. This can be done from inside or outside the vehicle with a cold knife or razor.

Cut the urethane. The urethane is a very strong, but flexible, polymer based adhesive. If you choose to cut from the outside you might have a problem when the windshield has been placed too close to the pinch-weld. If there is less than 1/8” of urethane then the knife will not have room to drag properly. This causes the glass to break and make a mess. Cutting the windshield out from the inside of the vehicle is the other option. You can use an extended handle razor knife and cut with a repeated dragging motion. Many installers also use power cutters which are faster but do more damage to the metal pinch-weld.

Remove the windshield from the car. This should be done with two people. Open the front door on either side of the car and reach one arm in to gently push the glass away from the pinch-weld. Get a hold of the glass from the outside of the car and lift it straight up off of the pinch-weld.

Preparing the Pinch-weld

Clean away any visible dirt with a brush and then plain water. Any contaminants on the pinch-weld will reduce adhesion of the urethane and the windshield.

Trim off excess urethane with a razor. The pinch-weld usually has old urethane about ¼” thick more or less and it needs to be trimmed down to 3/16” or about 3 mm

Remove any rust from the pinch-weld. Any rusty areas or areas with loose/damaged urethane will need to be sanded back to bare metal to remove all rust.

Tape off the area around the spot. You will want to cover any areas that were not sanded, and protect the inside of your vehicle using tape and sheets of paper or plastic. This will prevent the primer from getting on anything other than bare metal.

Prime any bare metal. This will help with adhesion of the urethane, but also is necessary to prevent the metal from rusting in the future. Priming the metal will require to spray on three thin, even coats of primer. Do not try to put on one heavy coat.

Install the New Windshield

Apply a primer to the frit band (the black band around the perimeter of the windshield). The purpose of the primer is to open the molecules of the frit band to accept the urethane molecules.

Apply the urethane with an electric caulking gun. If you do not have an electric caulking gun they can be purchased at your local hardware store. They range from about forty to three hundred and fifty dollars. The best thing for the new urethane to adhere to is the old urethane. It must be clean and free from dirt, oil or other contaminants. One problem installers have is wind blowing dust onto the pinch-weld before the urethane adhesive has been applied. The job can be done without an electric gun but it is much more difficult to get a consistent bead, making leaks likely.

Install the windshield. Carefully align the top bottom and sides by sight. Set the windshield on top of the pinch-weld. Some vehicles have mounting block for the bottom of the windshield to rest on, others do not. Be careful not to touch the frit band because the oils and dirt from your skin can contaminate the activated glass and reduce adhesion to the urethane. Some installers tape the windshield once it is in place. This holds it until the urethane dries.

Allow the urethane to set. Driving before the urethane has set completely is very dangerous. Depending on the type of urethane used, it will take between 1 and 24 hours to set. Follow manufacturer’s instructions regarding safe drive away times.

Replacing a Windshield Gasket

Remove any windshield clips. You will need a special windshield trim tool that you can slide under the windshield trim and remove it to access the clips. Once you have access to the clips, use the trim tool to carefully twist the clips loose.

Pull out the window gasket. It may help to cut the gasket so that you can straighten it out as you pull. If any of the gasket remains stuck to the windshield you can clean it off with a glass scraper or razor. Just be careful not to damage the windshield in the process. Spray the inside and the outside of the gasket with glass cleaning to help lubricate it.

Push one end of the new gasket into place. Once you get this end secured into the groove that your old gasket was in, you can start working your way around the windshield slowly.

Work the entire gasket into the groove. Go around the perimeter of your windshield working the gasket into the groove and being careful not to miss a spot. The entire gasket should fit snugly into the groove.

Tighten the windshield clips. You want to put the windshield clips back into their original place and tighten them so that they hold the gasket and windshield securely.