Windshield warnings

Windshields don’t just provide a clear, open view of the road. They are a key part of a vehicle’s occupant protection systems. (Image: GM)

The glass repairer contends they handled the claim and contracted the work to an independent glass repairer to perform the actual installation, and therefore are not at fault.

So who is? Could your shop be held liable?

For some clarification, I’ll direct you to Barrett Smith, president of Auto Damage Experts. He wrote: “Just because you engage another’s service doesn’t exempt you and your company from liabilities that may arise from a tragic loss such as this.

“Even recommending another service could land you in enough trouble to cost you tens of thousands in dollars proving you have no liability,” Smith said. “This is why it is so very important to be very careful and selective when choosing a sublet glass replacement company and other outside vendors to provide services for your business.”

While I’m not going to comment on the merits of the case, I do want to point out that it’s a reminder of the importance of correctly installing windshields and glass. Let’s take a look at the critical protection windshields provide, along with glass and repair information you’ll need to protect your customers and business.

In a rollover, the windshield provides as much as 60 percent of the structural support for the vehicle roof.

Engineered protection
Pop quiz: What is the function of a windshield?

1. It’s part of the vehicle structure.
2. It’s part of the frontal air bag system.
3. It helps restrain passengers in the vehicle during an accident.
4. It keeps the bugs off your face.

The correct answer is E – all of the above.

One reason rollovers are particularly dangerous is the potential for the roof to collapse, causing crushing damage to occupants that can result in brain and head trauma, paraplegia and death. Today’s vehicles are engineered so that the windshield provides much of the stiffness necessary to keep the roof from collapsing. In some cases, the windshield can account for up to 60 percent of the cabin’s structural integrity during a rollover.

Windshields also play a key role in front passenger protection during a collision. In some vehicles, the passenger’s side frontal air bag is deflected off of the windshield and the front passenger seat.

These two examples alone, I hope, are enough to remind all of us that properly installing a windshield involves far more than a call to a local vendor.

Replacement windshields with rain sensors aren’t yet available from manufacturers. You’ll need to recover the sensor for the old windshield and remount it. (Image: Subaru)

Glass facts
Your involvement with glass repairs starts with knowing as much as possible about windshields and other glass parts. In fact, you should know as much about this part as you already do about any other part you repair.

Automotive glass comes in two types: laminated and tempered. Laminated glass is constructed of two or more layers of glass with interlayers of another material — polyvinyl butyral (PVB) — bonded between them. This construction keeps the glass from shattering.

Tempered glass is created using thermal or chemical treatments that increase its strength over standard glass. Tempering creates balanced internal stresses that cause the glass, when broken, to crumble into small granular chunks instead of splintering into jagged shards.

You can tell which type of glass you’re dealing with using the notations printed on it. All windshields are marked with two letters: AS (American Standard). The AS is followed by a number that indicates the position in the vehicle where the glass, based on its optical clarity, can be used.

AS1 is the clearest glass, providing at least 70 percent light transmission. It’s laminated and can be used anywhere in a motor vehicle, though it’s typically found only in windshields.

AS2 also provides at least 70 percent light transmission. Unlike AS1, it’s tempered and can be used anywhere except the windshield.

AS3 provides less than 70 percent light transmission. It can either be laminated or tempered and is used throughout a vehicle. AS3 also is known as Privacy Glass.

Proper bonds
One of the keys — probably the key — to a safe windshield installation is the proper manufacturer-recommended use of the urethanes that bond the windshield to the rest of the vehicle.

To give you an idea of just how important this bond is for vehicle safety, let me direct you to the black band that runs around the edge of a windshield. This band is known as a frit. Its job is to block UV rays from reaching the urethane bond because urethanes, when left exposed to sunlight for prolonged periods of time, turn yellow, chalky and weaken. Vehicle manufacturers take steps like this to help ensure the bond stays as strong as possible, for as long as possible.

If you contract out your glass work, make sure your vendors are properly trained and use the latest products and equipment. You could be liable for any problems that occur because of their failure to perform a proper repair. (Image: Guardian Automotive Products)

Manufacturers also have been turning to a new, more sophisticated generation of urethanes whose bonding strength allows them to contribute to efforts to reduce vehicle weight. Manufacturers today are using special, high-modulus polyurethane (PUR) adhesives to bond the windshield. Because these urethanes are more rigid when cured, they actually allow the manufacturer to minimize the thickness of some of the steel in the vehicle.

Notable here is the fact that not all high-modulus polyurethanes, or other urethanes, are the same. In fact, it’s critical that you remember that each urethane uses a unique set of primers integral to the bonding process. Each urethane also has its own cure time, which establishes when the vehicle is safe to drive. If the urethane is not cured, the safety of the vehicle will not have been restored.

Other factors also affect the urethane bond. For example, a pinch weld that has been repaired or replaced needs an epoxy primer or a similar product applied to the bare metal surface. Some vehicle manufacturers allow refinishing of the surface, while others only want the epoxy primer applied. All OEMs state that there should be no body filler applied to the pinch weld where urethane is used, due the fact that the urethane will not adhere to the substrate. As with repairing/replacing any other part, working with glass means turning to OEM repair instructions.  

Other repair considerations
The addition of electronic systems to the windshield has created new repair requirements. Working on these systems often involves turning to non-conductive urethane, which do not interfere with sophisticated electronics.

Many windshields and backlites today feature embedded antennas and defroster grids. If the adhesive contacts the antenna or defroster lines when the part is installed, a non-conductive adhesive should be used. Non-conductive adhesives prevent interference with antenna systems and heated defroster systems that are contained in the glass.

Many new glass parts have the antenna, defroster connections or buss bars around the edge of the glass in the same area that the adhesive is applied when installing glass. Using a conductive adhesive will affect the performance of the electrical system. Again, this means turning to a non-conductive product.

Vehicles featuring rain sensor modules in the windshield also require special repair