Any way a glass can get smashed by itself - Page 2 - PeachParts Mercedes-Benz Forum

t walgamuth · #1 02-24-2008, 07:58 AM

On my 62 190c, once in very cold weather a friend slammed my door really hard and the glass just all came inside the car.

I also slammed my wifes's car door once in anger in very cold weather and did the same thing....'72 corolla.

Yuck!

Tom W

rg2098 · #2 02-24-2008, 10:55 AM

Heres an interesting thought. The new Cadillac DTS (and plenty of other makes) have heated washer fluid nozzles. The DTS heats to 140 degrees. Granted it probably cools off quiet a bit before hitting the windshield (for sake of argument lets say it hits at 80 degrees), it doesn't seem to be a problem with sub zero temp windshields.

2.5Turbo · #3 02-24-2008, 05:51 PM

Yeah, there are a few things that could make tempered glass break seemingly spontaneously. Tempered glass is put under enormous stress by the tempering process, and it is that stress that keeps it strong. Fully tempered glass has a surface compression of 10,000psi, and edge compression of 9,700psi or more. If the glass is slightly chipped on an edge or surface, most of the time the entire thing will go. But if the chip isn't deep enough to penetrate the stressed outside layer, it won't break until the chip propagates all the way through that outside layer.

Another cause, although very rare, is nickel sulfide inclusions in the glass. Pieces of glass that have one usually break during the tempering process, but sometimes they make it through. These expand over time and eventually cause the glass to break.

I looked all this stuff up a couple years ago when the rear window of the Volvo wagon seemingly spontaneously broke while driving. We're pretty sure it wasn't done by somebody on the side of the road because it was in an area where there weren't any houses, people, or cars.