by Bob Beranek
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I read a thread on glassBYTEs.com™ the other week titled “2014 Hyundai Sonata Stress Cracks,” and a couple of things came to mind. Some of you know that my son Jay works for a large dealership group here in Madison, Wis. One of the makes his dealership sells is Hyundai. This past week Jay told me that he has personally witnessed a number of 2012, 2013 and 2014 Hyundai vehicles with stress cracks in the windshields. Although Jay had a couple of thoughts on the cause of the breaks, I needed to see it myself before making a diagnosis.

Another thing he said piqued my interest. He said that the new Hyundai windshields were more difficult to install now due to the thinness of the urethane bead between the glass and the pinchweld. He said the thin bead makes the glass more difficult to cut out. According to Jay, it is hard to get a cold knife blade under the glass, and the glass breaks up easily during removal. Interesting.

A unibody vehicle is one that has a great deal of body movement as it travels a roadway. It ebbs and flows with the roadway, twisting and turning in all directions. All of the body panels must be manufactured to take this movement into consideration. The sheet metal of the body has a certain amount of flexibility in its movement but the glass panels are less flexible. To account for the movement of the body in relation to the stationary glass parts, the engineers use the urethane adhesive to cushion and allow the movement of the glass in the opening. If the urethane bead is thin or too stiff, the glass will not move sufficiently and may stress break. Could this be the reason for an increase of stress breaks in the Hyundai?

Another observation made is that at Jay’s dealership they used to buy aftermarket glass for Hyundai replacements, but they found that aftermarket glass was frequently out-of-bend, so they went back to using OEM glass. If the aftermarket glass is slightly out-of-bend, then patting or spanking the glass to seal it could cause a break during installation. In addition, glass that is out-of-bend will give when patting it into place, but it will then spring back, causing the urethane to string out. This may cause leaks or bonding issues. It is always better to smooth out the glass to seal rather than patting or spanking it into place.