Can auto glass spontaneously explode? (1 Viewer)

[Luis S]

Worked with glass for 6 years.Tempreture will definately do it.And it dont take much.Any mirror or glass suffering a rapid change in tempreture can break.But sometimes it happens and then sometimes it dont.Its totaly upredictable, though its scared the beejeezus out of me a few times!
Luis S

 

[Philip_G]

I wonder what it is, I drive around up here when it's -20, to -35 or maybe even a little colder sometimes, and nothing's popped on me yet.
hehe it's been so cold that the speedometer doesn't work, that's how I know when it's fffffffucking cold out
does it have to do with the rate of change of temp?

 

[Patrick Sun]

Well, I guess I can sort of sleep easier at night knowing that it's possible I just suffered some bad luck with my driverside window.
I spent half an hour today with the new shop vac sucking out all the glass fragments out of my car. That was such a good purchase.
Tomorrow I get to check out junkyards to see if I get lucky with that piece of window glass I need, or I get to pay through the nose for the same piece of glass from a body shop.

 

[Mike Frezon]

Tomorrow I get to check out junkyards to see if I get lucky with that piece of window glass I need, or I get to pay through the nose for the same piece of glass from a body shop.

Full glass coverage on your car insurance, my man! It only adds a couple of dollars to your premiums and I can't tell you how many times I've had to replace huge mini-van windshields after some truck in front of me kicked up a stone. Very worth it! Has saved me several hundred dollars at least three times.

 

[Lee L]

Is this a problem only on US automaker designed cars? Could be a manufacturing "flaw" that saved them a few pennies per window...

No, this is a problem commeon to all pieces of tempered glass. All the windows in your car are tempered except the windshield, which is laminated glass. After the glass is formed and cooled, it is heated again and rapidly cooled by dipping in a water bath. This slightly alters the crystaline structure of the glass, making it much stronger and safer but rendering it suceptible to breaking spontaneously.

The edges of any piece of glass are the easiest place to break it and that is why temperature changes can cause this sometimes. The glass expands and contracts and pieces of dirt or metal from the manufacuturing process of the car (or office building)can be wedged in between the weatherstipping and the edge of the glass, creating a pressure point and boom. The tempering causes the glass to break into the tiny pieces. Obviously much safer than having long jagged shards flying around in a wreck. This is also why building codes require tempered glass in any operable door or window or in any fixed piece next to an operable door.

Incedentally, the tepering makes it really easy to break into a car since all you have to do is stick a flat head screwdriver into the weatherstripping in between the edge of the glass and the metal and twist it and the glass just pops. Also, anyone with a Camaro or Firebird that has a channel-less door should be able to bend the glass out enough to actually reach in and unlock the vehicle if you lock your keys in.

 

[Patrick Sun]

Here's some photos:
Photo 1
Photo 2
I did get my window replaced this morning (after the rain subsided, of course). I will have to check and see if I have glass coverage on my car insurance policy.

 

[Lee L]

Someone almost definitely did that. Maybe soome kids drove by and shot it with a pellet gun. You can clearly see the point of impact and it does look like maybe someone, after breaking it, reached in near the mirror. Are you sure nothing was taken?

 

[BrianW]

Lee's right. When tempered glass shatters spontaneously, the cracks form an amorphous pattern that don't indicate an impact point, which can clearly be seen in your photos.

 

[Wayne Bundrick]

Incedentally, the tepering makes it really easy to break into a car since all you have to do is stick a flat head screwdriver into the weatherstripping in between the edge of the glass and the metal and twist it and the glass just pops.

Yep. It's lesson number one for up and coming car thieves. Lesson number two is learning which cars have poorly designed ignition lock mechanisms that are easily subverted. I used to have such a car. I had a Chevy Caprice stolen from the parking lot where I work. It wasn't even night or dusk, it was at high noon. The thief probably entered the car and had it started and was gone quicker than I could do it using my key.

 

[Patrick Sun]

Nothing I valued was takened (if anything was taken at all). The driver side door was still locked after the window was smashed, so it might have been a smash-n-grab, but nothing was in the driver seat, which is all the vandals could reach from that entry position. I have a flip-door model for my CD/MP3 car deck, and the door was flipped up, so the face could not be seen, but the vandals didn't even take it (or open the door to get to it - the rest of the window could have come crashing down if they closed the door hard).

 

[Ted Lee]

since nothing was taken, it was probably an "accident" of some sort.
i came out to my car once and saw a perfectly cracked driver side window. it didn't shatter because it was tinted. and guess what i found by the front tire? a nice, round, very hard mini-basketball. a few minutes later the neighbor comes out and is like, "wow...what happened....and by the way, i think that's my kid's ball!". i'm like, uh...yeah....well....what do *you* think happened. i could tell the person was NOT going to cop to it...i knew i was screwed.
dang patrick...what was your original question?
oh yeah...glass can definitely shatter. when i lived in the mojave desert, the rear-window of my dad's car completely blew out. all the glass was all over the driveway. of course, it was something like 110 degrees and he had all the windows closed. it was a good lesson though. now, no matter what the temperature is, i'll leave my sunroof cracked just a little bit.

 

[Michael St. Clair]

Once some kids driving around just heaved a rock through my wife's rear window while the car was parked.

Not to take anything, just for "fun". This gang of "fun-loving" kids had been spotted many times doing this.

I once had a rear-window busted in for theft.

They left the blaupunkt in the dash.

They left the radar detector under the seat.

They took a cheap ($60) sports coat.

 

[Craig Robertson]

concerning spontanious breakage, i have seen it happen on a couple of occasions. one time was temperature related, my bosses Nissan Pathfinder popped one of the rear side windows on a hot day in Hilo, Hawaii. the other was not temp related, don't know why it happened. i was driving on the freeway in Seattle in a Ford Explorer with some co-workers when the passenger side widow exploded, scaring the shit out of all of us. at first we thought it was hit by something, but we couldn't find any evidence of that.

non-spontanious glass breakage:
i had just climbed into bed one evening and the neighbor called. she had just come home and when she drove past my house she saw broken glass on the street next to my work truck. i went out to check and the driver side window was broken out. of course, as i'm standing outside next to the broken out window with a flashlight, a cop drive by and wants to know what i'm doing. once i explain that it's my car, he starts to check things out. the alarm hadn't gone off, but when he reaches in to the vehicle, then it does. seems the practice of the thief is to drive by the target vehicle and shoot a ball bearing at the window, this pops the window and usually doesn't set off the alarm, then they come back by and grab stuff out of the car.

 

[Ted Lee]

non-spontanious glass breakage

i'm so stealin' that phrase!

 

[wayne-sun]

FYI - If a window is broken by force the majority of the glass will end up on the side from which the force was applied. When force is applied to glass it flexs before it breaks, the actual breaking of the glass is caused when the glass is fighting to return to it's normal state and as such the glass is actually going towards the applied pressure. If the glass is inside it broke from inside.

 

[Ted Lee]

wayne -
i'm certainly no physics expert, but i have a couple of questions/thoughts?
i think it would require some very strong glass trying to return to it's normal state to overcome a force strong enough to break it in the first place?
also would your theory still apply with curved glass? the reason i ask is that auto-glass is usually curved. it has a natural "tendency" to bow outwards. so, if an internal force (such as a very hot car interior) blows the glass out, would your theory still work? it would seem that the curved glass plus the extreme force would still blow the glass outwards.
not being sarcastic...just curious.
ted

 

[Patrick Sun]

Where's the Atlanta CSI unit when I need them!

 

[wayne-sun]

Now you got me. I never took into account the curvature of the glass so... not sure. Flat glass is what I was referring to before.