Bonded windshields require special tools and special removal procedures to be removed without being broken. For this reason we recommend that you refer all removal and installation to a qualified technician.
When replacing a cracked windshield, it is important that the cause of the crack be determined and the condition corrected, before a new glass is installed.
The cause of the crack may be an obstruction or a high spot somewhere around the flange of the opening; cracking may not occur until pressure from the high spot or obstruction becomes particularly high due to winds, extremes of temperature, or rough terrain.
Suggestions of what to look for are described later in this section under inspection.
See Figures 1, 2 and 3
When a windshield is broken, the glass may have already have fallen or been removed from the weatherstrip. Often, however, it is necessary to remove a cracked or otherwise imperfect windshield that is still intact. In this case, it is a good practise to crisscross the glass with strips of masking tape before removing the it; this will help hold the glass together and minimize the risk of injury.
If a crack extends to the edge of the glass, mark the point where the crack meets the weather strip. (Use a piece of chalk and mark the point on the cab, next to the weatherstrip.) Later, when examining the flange of the opening for a cause of the crack start at the point marked.
The higher the temperature of the work area, the more pliable the weather strip will be. The more pliable the weather strip, the more easily the windshield can be removed.
Before removing the glass, cover the instrument panel, and the surrounding sheet metal with protective covering and remove the wiper arms.
There are two methods of windshield removal, depending on the method of windshield replacement chosen. When using the short method of installation, it is important to cut the glass from the urethane adhesive as close to the glass as possible. This is due to the fact that the urethane adhesive will be used to provide a base for the replacement windshield.
When using the extended method of windshield replacement, all the urethane adhesive must be removed from the pinchweld flange so, the process of cutting the window from the adhesive is less critical.
Special tool J-24402-A, Glass Sealant Remover Knife, or its equivalent is required to perform this procedure. To remove the windshield:
- Place the protective covering around the area where the glass will be removed.
- Remove the windshield wiper arms, and the interior garnish moldings.
- Remove the exterior reveal moldings and the support molding from the urethane adhesive by prying one end of the molding from the adhesive. Pull the free end of the molding away from the windshield or the pinchweld flange until the molding is completely free of the windshield.
- Using J-24402-A cut the windshield from the urethane adhesive. If the short method of glass replacement is to be used, keep the knife as close to the glass as possible in order to leave a base for the replacement glass.
- With the help of an assistant, remove the glass.
- If the original glass is to be reinstalled, place it on a protected bench or a holding fixture. Remove any remaining adhesive with a razor blade or a sharp scraper. Any remaining traces of adhesive material can be removed with denatured alcohol or lacquer thinner.
When cleaning windshield glass, avoid contacting the edge of the plastic laminate material (on the edge of the glass) with volatile cleaner. Contact may cause discoloration and deterioration of the plastic laminate. Do not use a petroleum based solvent such as gasoline or kerosene. The presence of oil will prevent the adhesion of new material.
An inspection of the windshield opening, the weather strip, and the glass may reveal the cause of a broken windshield. This can help prevent future breakage. If there is no apparent cause of breakage, the weatherstrip should be removed from the flange of the opening and the flange inspected. Look for high weld or solder spots, hardened spot welds sealer, or any other obstruction or irregularity in the flange. Check the weatherstrip for irregularities or obstructions in it.
Check the windshield to be installed to make sure that it does not have any chipped edges. Chipped edges can be ground off, restoring a smooth edge to the glass, and minimizing concentrations of pressure that cause breakage. Remove no more than necessary, in an effort to maintain the original shape of the glass and the proper clearance between it and the flange of the opening.
There are two methods used for windshield replacement. The short method described previously in the removal procedure is used when the urethane adhesive can be used as a base for the new glass. This method would be used in the case of a cracked glass, if, no other service needs to be done to the windshield frame such as sheet metal or repainting work.
The extended method should be used when work must be done to the windshield frame such as straightening or repairing sheet metal or repainting the windshield frame. In this method all of the urethane adhesive must be removed from the pinchweld flange.
See Figures 4, 5 and 6
To replace a urethane adhered windshield, GM adhesive service kit No. 9636067 contains some of the materials needed, and must be used to insure the original integrity of the windshield design. Materials in this kit include:
- One tube of adhesive material.
- One dispensing nozzle.
- Steel music wire.
- Rubber cleaner.
- Rubber primer.
- Pinchweld primer.
- Blackout primer.
- Filler strip (for use on windshield installations for vehicles equipped with embedded windshield antenna).
- Primer applicators.
Other materials are required for windshield installation which are not included in the service kit. These include:
- GM rubber lubricant No. 1051717.
- Alcohol for cleaning the edge of the glass.
- Adhesive dispensing gun J-24811 or its equivalent.
- A commercial type razor knife.
- Two rubber support spacers.
- Clean all metal surrounding the windshield opening with a clean alcohol dampened cloth. Allow the alcohol to air dry.
- Apply the pinchweld primer found in the service kit to the pinchweld area. Do not let any of the primer touch any of the exposed paint because damage to the finish may occur. Allow thirty minutes for the primer to dry.
- Follow the steps listed under Short Method for the remainder of the procedure.
- Install the support molding onto the pinchweld flange from inside the vehicle. The joint of the molding should be located at the bottom center of the moulding.
- Thoroughly clean the edge of the glass to which the adhesive material will be applied with a clean alcohol dampened cloth. Allow the alcohol to dry.
- Apply the clear glass primer in the kit to the inner edge of the windshield from the edge of the glass inward 1.0mm. Apply the primer around the entire perimeter of the glass. Allow the primer to cure for thirty minutes.
- Apply the blackout primer to the glass in the same area as the clear primer. Allow the blackout primer to dry to the touch.
- Place two rubber blocks onto the base of the pinchweld flange. Place the blocks in line with the last screw on either side of the cowl grille cover.
- With the aid of a helper, lift the glass into the opening. Center the glass in the opening, on top of the support molding.
- Check the fit of the reveal molding. If necessary remove the glass and cut away additional urethane to give the proper windshield height. Place the glass in the window opening.
- Cut the tip of the adhesive cartridge approximately 5mm from the end of the tip.
- Apply the adhesive first in and around the spacer blocks. Apply a smooth continuous bead of adhesive into the gap between the glass edge and the sheet metal. Use a flat bladed tool to paddle the material into position if necessary. Be sure that the adhesive contacts the entire edge of the glass, and extends to fill the gap between the glass and the primer sheet metal (extended method) or solidified urethane base (short method).
- Spray a mist of water onto the urethane. Water will assist in the curing process. Dry the area where the reveal molding will contact the body and glass.
- Install new reveal moldings. Remove the protective tape covering the butyl adhesive on the underside of the molding. Push the molding caps onto each end of one of the reveal moldings. Press the lip of the molding into the urethane adhesive while holding it against the edge of the windshield. Take care to seat the molding in the corners. The lip must fully contact the adhesive and the gap must be entirely covered by the crown of the molding. Slide the molding caps onto the adjacent moldings. Use tape to hold the molding in position until the adhesive cures.
- Install the wiper arms and the interior garnish moldings.
The vehicle should not be driven and should remain at room temperature for six hours to allow the adhesive to cure.