Fixed glass, commonly used for windshields, back glasses and quarter glasses, is simply stationary glass usually installed with an adhesive. A good understanding of the correct and “legal” way to replace glass is essential in providing a professional and safe glass installation.
It’s important to note that certain standards should be met when replacing a windshield. When original equipment manufacturers build a car they must meet the Federal Motor Vehicle Safety Standard (FMVSS). Your repair should restore that standard of integrity. Installing a windshield incorrectly could result in serious injury to the public, even death in the event of a collision. Liability must be considered and understood when performing glass replacement.
Using a complete system of products from one manufacturer is highly recommended. Understanding and knowing the proper steps in glass replacement are critical to follow: do not skip any recommended procedures.
Even if you are subletting your glasswork you should know the process so that you can verify you are getting a quality, safe job. Also be aware that subletting the repairs to an independent glass installer does not transfer your liability. You are still liable for the repairs. Employing a little risk management here will save you a great deal of exposure for your business.
Allowing a third party to install glass in your shop—where you have nothing to gain and everything to lose—should be discussed with your legal counsel. Direct repair program (DRP) contracts insurers have made with glass companies should be carefully weighed with the risks involved.
With those few caveats, let’s get started.
Preparation
The first step for a successful installation is planning and preparation. Be sure you have the correct glass (tint, shade, antennae, Heads Up Display, etc.), a reveal molding if needed, the necessary materials that are all one product line and within the expiration dates, safety equipment and the correct tools for the job. It is also advisable to document the installation process by recording the glass manufacturer, products used, VIN, delivery time, and what the conditions were the day the glass was installed. You may never need to defend yourself from a lawsuit, but these could be a few minutes well spent.
With a vacuum cleaner, vacuum the defroster vents with the defroster running on high to remove any glass slivers that may have found their way into the vent. After they have been cleared, cover the vents with tape or masking paper to prevent any foreign objects from finding their way into the vents.
Remove the interior parts, such as the mirror, trim panels and sun visor, and loosen the headliner if necessary. Be sure your hands and clothes are clean so as not to dirty the upholstery. If wires are exposed from any of the removed parts, be sure to secure them out of the way. After opening the hood, remove the exterior parts such as the wipers, cowl panel, trim, antennae, etc. If possible, remove the glass stops so as not to damage them when cutting out the glass. If the windshield molding is reusable, remove it now and see if it is OK. If not, you should already have a replacement available.
Full cut-out method
Before cutting, protect the paint, if necessary, along the front edge of the roof and A pillars with tape. Now insert the cold knife into the urethane at the top, center of the windshield, and begin to pull the blade toward you, keeping the tool tilted slightly away from the cutting direction. This will allow you to cut the urethane as close to the glass as possible. Be sure to wear safety glasses and leather gloves for protection. When you reach the corner of the windshield, rotate the knife and begin to cut along the side, pulling toward the bottom of the windshield. When you reach the bottom, go to the other side and repeat the process. When you get to the bottom, do not try to cut the urethane with the cold knife unless you determine it will do so safely, without damaging the dash. Check how far up the urethane goes under the windshield and how many layers there are. Check to be sure the dash is not in danger of being cut by being too close to the windshield. Place a foam pad between the upper windshield and the center of the roof panel to hold the glass away from the pinch weld. Cut the urethane along the bottom of the windshield, using a long knife, being careful not to cut the dash.
Once all of the urethane is completely cut, remove the glass. Check to see if the customer has any stickers on the windshield that need to be saved. Be sure the new windshield has the correct brackets on it before disposing of the old glass.
Dry fit
Once the windshield is removed, get the new windshield and tape up the edges with masking tape so that the edges won’t accidentally get chipped. Replace the blocks if they were removed. Place the windshield into the vehicle and center in the opening. Once centered, place two pieces of masking tape—6-in. to 10-in. long—6 in. in from each side at the bottom and cut at the edge of the glass to use as alignment markers.
Trim old urethane and prepare pinch weld
Now that the old glass is removed, clean the pinch weld of any loose debris with a brush or low compressed air. Be careful to not get the debris on unprotected interior parts. With a knife or scraper, cut the existing urethane left on the pinch weld to 1 mm to 2 mm in thickness. When a 6-in. strip has been cut, pull up on it as you continue to cut, checking for good adhesion of the old urethane to the pinch weld.
If there are any places the urethane pulls loose, determine why. If it is corrosion then you should strip the affected area down to clean bare metal and re-prime with two-part catalyzed primer. If it is just an area of poor adhesion, clean and prime with windshield primer, being careful not to get any on the freshly trimmed urethane. When you finish removing the excess urethane, prime any scratches you might have made with the knife. Using a cotton swab saturated in windshield primer, brush the scratch with primer in one direction only. Do not dip it back into the primer container again and contaminate the bottle. If a new panel has been welded on and the pinch weld has fresh plug welds, use two part primer to cover the bare metal spots. Do not use any plastic filler on the pinch weld. Place a 3⁄4-in. strip of tape to cover the mating surface of the windshield before top coating. Only one vehicle manufacturer prefers the pinch weld be top coated. Refer to OEM recommendations for instructions.
Prepare the windshield
Place the new windshield on a soft, non–abrasive work surface to clean it for installation. Remove the protective tape from the edge and clean both sides with the recommended solvent in the product line you are using. When it has been thoroughly cleaned, and before installing, re-clean the center of the inside side and the outer side with a glass cleaner that has no ammonia.
Apply the pinch weld primer to the glass mating area, if the urethane manufacturer recommends it. Refer to the product data sheet for the manufacturer’s recommendation. If the factory application had a foam bead on the edge of the pinch weld, make sure it is in good shape or replace it.
Applying the urethane
Now it is time to apply the urethane to the pinch weld. Wear protective gloves for this operation. Cut the tip of the applicator to match the size of the original urethane bead. Then cut a V-notch in the applicator about 13-mm long and about 6-mm wide at the base of the newly cut-end of the applicator. It will take a little more than one tube so have the second one ready. Start applying the urethane in the middle at the top of the windshield opening, holding the applicator at near a 90-degree angle to the pinch weld. When you get to the corner, keep the size the same and lift up the applicator carefully and stop. Go to the bottom middle and apply the same as the top. Be careful and do not get any urethane on wires and connectors. When you have reached the corner, stop and break off as before. Start at the top corner and apply the bead to make as seamless a joint as possible, and move down to the bottom bead. If the intersections are uneven, use a paddle to shape and smooth the joints. Repeat the process on the other side. Putting the vertical bead on last may save you from messing it up when you reach to apply the bottom bead and accidentally lean into the fresh urethane on the side bead.
Don’t overdo it—the old adage that more is better is not good here. The bead should be the same size as before. Too much urethane can cause drainage, adhesion and cure problems.
Once the urethane is applied, it is time to set the windshield in. Two people are recommended for this operation. Be sure the correct time has elapsed to allow the primer to cure. Set the windshield on the blocks at the bottom first, being careful to not touch the mating surface with your hands, and lean the glass into the opening. Be sure to line up the tape strips at the bottom as you install the glass.
Once the glass is laying on the fresh urethane, press slightly, do not hit or slap the glass. The thick-viscosity urethane should not be pressed too hard and squeezed out too far. While the urethane is fresh, install the reveal molding. If it is the old one, it should have its old shape and you will know where the corners are. If it is a new molding, you will want to lay it around the glass and be sure it is installed with the equal amount on each side. Either way it is advisable to heat the molding by laying it in the sun on a hot day, using a heat gun, or submerging it in hot water.
Leak-checking the windshield
Now that the glass is in, it is time to check for leaks while the urethane is fresh. The water method is the most common way, or if you want to try a newer method, you can use fluorescent dye in water. If using the water method, be sure to start at the bottom and work your way up each side to the top. An ultrasonic tool works well also. If a leak is detected, press gently on the area and recheck it. If a little more urethane is needed, apply some to the leak area and recheck.
Reassembly
Reinstall all of the trim and hardware that was removed. Be careful to clean your hands before touching trim and upholstery. Install stickers if necessary.
One caution here is to be sure you follow the manufacturer’s cure time and not allow a vehicle to be delivered until the windshield is properly and safely cured. The recommended cure time is documented on the product data sheet.
Now that you are finished, you should feel confident that you have performed a professionally superior and safe installation.
