Your car windshield does more than just block dust and bugs from hitting you while driving. It reduces your chance of being thrown from the car in a crash, keeps the roof from crushing if the car rolls over and even helps the airbag deploy properly. If your windshield needs to be replaced due to cracks, it must be done so precisely.
Remove the rear view mirror inside the car. Unscrew one of the mirror base's two screws. You can then slide the retaining block and mirror out.
Remove the windshield wipers. Lift them into the "cleaning position" so they will be easy to reinstall. Pry them up with a large flat screwdriver between the large nut and the arm while rocking the arm with your other hand.
Seal the interior heater vents with masking tape. This will prevent any flakes of broken glass from falling into the vents, which could blow into the car.
Check if the gasket is still good. If the rubber is no longer soft or has any cracks, you should replace it. This means you can cut it away and make the glass removal much easier.
Push a strong knife into the center of the rubber, making sure you don't hit the glass. Cut all the way around to remove the rubber. You can now push the glass out from the inside.
Remove the window more forcibly if the gasket can still be used. First, break the glass sealant applied by the manufacturer. Run a wooden stick along where the gasket and frame meet.
Gently push the glass out with your foot from the passenger seat. Don't kick the glass. Push it under the inside lip at the top with the wood stick to get the rubber started through the frame.
Have someone else on top of the car in front of the windshield. This person should catch the glass when it comes out.
Prepare the frame for reinstallation. Wipe away all rust from the frame, clean the dashboard and remove all sealant from the new gasket. Leave the gasket in the sun to make it warmer and more flexible.
Fit the gasket on the windshield. Run a small bit of sealant along the gasket's bottom half channel. The heavy side goes to the inside and the side with the slit goes to the outside.
Rub petroleum jelly into the outer rubber groove, with a little extra at the top and bottom center. Run a heavy nylon cord around the outer groove starting at the bottom center, leaving two 2-foot-long ends out in the center.
Lay the windshield in place from the car's outside. Make sure the loose cords are in the car's inside.
Pull one cord out slowly across the frame, to pull the rubber lip in place. Someone else should press the rubber against the car to prevent the lip from slipping off.
Clean up any extra petroleum jelly from the frame. Reinstall the wipers and mirror.
