How To – Replacing Your Cars Windshield

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    Maybe you were driving down the road and a truck kicked up a rock or you were the victim of a storm and a branch fell on your car. No matter the reason there are times when you need to replace the windshield in your vehicle so lets look at what the process will entail.

    The first thing you should understand when you are presented with the fact your windshield is going to be replaced is that it is not the end of the world.  If the glass has some damage that is not directly in your view then you can continue driving the vehicle to a safe location.  If you happen to have some sun glasses now would be a good time to put them on just in case.

    Although the actual process of replacing a front or back windshield is not technically difficult it is hard to do by yourself especially if you are untrained. I will cover some of the steps to perform the work yourself but think of it this way you can struggle and maybe come out with a windshield replacement that won’t leak and it will take you most of a day to do yourself or you can call someone and for a pretty cheap price have them do the work that is warrantied.

    If you are restoring a vehicle you can remove the glass yourself and do any welding or rust repair then call in a professional to replace the glass in about an hour.

    Doing The Work Yourself

    To replace the glass yourself you will need to remove the old glass first.

    Remove the trim inside the car and unplug any electric window heater lines and tape the side of the wire that is attached to the window to the window.

    Remove your Windshield Wipers.

    Remove the plastic molding strip that goes around the sides and top of the window by prying up one lower corner and pulling it out and around the glass. It should come out pretty easy.

    If you are working on a vehicle with stainless moldings then you will need a special clip remover that is inserted behind the molding to pry the clips off. Be careful not to bend the molding in the process.

    Now remove the plastic vent cover that goes across the bottom of your windshield on the outside.  You can probably get away with removing the upper screws that hold it in place and if necessary hold it back with tape to the hood.

    Apply a  few layers of duct tape on the painted surface around the sides and top of the window so you do not damage the paint in the process. A professional will probably skip this step because they are use to doing the work but if its your first time you may leave a nice scratch with the window sealer cutter.

    Front and rear windshields are glued to the rim of the opening with a flexible urethane material they are not normally held in with clips or the molding that goes around the window. Some designs do use a gasket type material but that is less common.

    If you are working on a very old classic car the material that holds it in is a bituminous tar type material and it will be a little harder to cut the window away from its frame.

    To cut the window free you will use a cutter that looks something like a screw driver that has had its tip bent 90 degrees to fit between the glass and the metal frame of the car.

    Often it can take two passes with a cutter. Using a short half inch blade first then a blade that is about an inch long to get deeper into the urethane material. If a window mechanic was performing the work they would have two cutters and follow one behind the other so they would not lose the grove of the first smaller cutter.

    Insert the cutter in the top center of the window where it is most flexible and pull the cutter out towards the side of the car.  Try not to stop while making the cut and hold the cutter against the glass so the tool will not slip free. When you get to the top outside corner follow down the side of the window that you are working on.

    Now move to the other side of the vehicle and performe the same process. Start in the middle of the top of the window and pull out to the side of the car holding the tool tight to the glass. Now follow down the side of the window.

    The top of the window should now be free and the windshield should be hinged at the bottom of the glass.

    To remove the lower seam of urethane you will need to enter the car and push the glass about 10 inches out at the top. This will give you room to place a different long straight cutter into the urethane and cut from the center to the outside just as you did for the top.

    Cutting the lower urethane sealer free is more difficult and you should probably have a helper hold the glass as you make the cut. If you have a helper hinge the windshield out as far as you can to give you more room between the dashboard inside the car and the glass.

    Prepare New Glass For Installation

    Using a scraper you need to remove all of the old urethane sealer that is lose.  If there is rust in the window channel you should take time to repair and paint the surface making sure you don’t modify the opening and make it difficult to fit in your new piece of glass.

    First start by cleaning the new piece of glass you are installing with an ammonia glass cleaner not soap. The glass needs to be clean of all grease to bond well to the urethane adhesive. Most manufacturers will suggest that you use a glass etching liquid. This liquid is not quite as strong as the type used for etching security numbers into glass but you could cause some damage so apply it carefully around the edge and do not reach over the glass with the pad or paper towel you are using to apply it. No drips in the center.

    At this point a professional will install a new trim  molding that you pulled off around the side and top of the window. It is up to you whether you want to do it now or later but by doing it before you replace the glass you are likely to have the glass centered in the opening by the molding and that can help a lot.

    If you have heater wires tape them back to the center of the window so they won’t get in the way while you are positioning the new window in the frame

    Installing the Window

    If you thought getting the old glass out by yourself was difficult you are in for a treat trying to get the new piece back in.

    After you have cleaned the window opening and prepared the glass you will use a caulk gun to apply a bead of Urethane sealer / adhesive to the window channel.  You want to make sure that you place the bead of urethane as the manufacture suggests. If you place the bead too close to the outside edge of the window frame it may sag before it cures and not look too nice from inside.

    Now is the fun part. YOU REALLY NEED A HELPER TO INSTALL THE WINDOW.

    A professional that does the work every day has learned how to quickly place the window in the opening by themselves in one quick motion. They often use special suction cups to give them a better grip in the center of the window too. It is definitely a skill only time and many tries can teach.

    If you have a helper you will want to position the bottom edge of the window first then lean the top part down into the window frame.

    You really only get one good try with this so make sure the bottom sides of the window are lining up correctly and centered as you lower the top edge into the urethane.

    Once the window is in place and the moldings have been pressed into place with the palm of your hands you want to press down firmly around the window a few times then look on the inside of the car and make sure the glass is seated.

    Now because it takes an hour or so for the Urethane to cure hard enough to support the window you want to place about four 10 inch strips of duct tape at the top of the window to the roof  holding it in place. Place long ways so 5 inches is on the roof 5 is on the window …… not a half inch on each surface that will not hold.

    I would leave the tape on overnight if you can but a few hours should do.

    NOTE

    This is a very difficult process to do well for the first timer especially if you are doing it alone but it is very possible you can do the work alone or with a helper or two.

    The hardest part is probably positioning the new window in the opening.  Although the glass is not impossibly heavy to carry by yourself when you get into that stretched out position across the car or van or suv it can get very heavy and difficult to position in one shot.

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