Saturday, December 11, 2010

Why Does Glass Break for No Reason?

Replacing a rear window was not what I had originally planned to do on my snowy Saturday morning.

My poor E30's rear window was completely shattered but remained completely intact until I slammed the door. No foul play is suspected as my CD player and iPod remain in the vehicle. No branches or small rocks are present in the area. Completely clean crime scene - no evidence.

Does water get in the driprails and freeze? Was my chassis tweaked, stressing the window? Is this an act of local wildlife? If anyone has any insight, please enlighten me in the comments below!


  1. I've seen this happen twice and the only theory that makes sense to me is internal stresses from the tempering process. I had a side window shatter as I gently laid it on the ground once. Some pieces went as far as 10 feet.

    Water shouldn't be able to get under the glue and if it did wouldn't it just raise the glass up?

  2. Internal stresses sound more legit than my theory. I heard another theory that on cold days where there is alot of sun, the temperature of the inside of the car can be drastically warmer than the outside, causing the glass to shatter.

    These cars have a lock strip holding the glass in that doesn't seal. My thought was that if water got between the seal and the window and froze, it could raise the glass up unevely.