Cracked rear glass


2112

Blue/white 06'
Mark II Lifetime
Whew! when I first saw those "Red Hot Mojo" chips I thought we were going to have an explanation involving human gas pressure....

:lol

The triple pane window is a single unit. Not hard to replace, but a PITA because of all the cleaning of old adhesive, surface prep, precision locating of the replacement glass.

Did you do it from the cabin side?
 

Xcentric

GT Owner
Mark II Lifetime
Jul 9, 2012
5,213
Myakka City, Florida
[emoji38]



Did you do it from the cabin side?
I didn't do it. I read how you do it.

Engine side.

But you have to take some of the interior apart...headliner, seat belt retractors. And cut through the old adhesive.

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AJB

GT
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Jun 28, 2006
2,943
Bloomfield Hills, Michigan
interesting.... when mine cracked...( and I have not yet picked up my car from ICON to look closer) it was a very clean, single crack horizontally across the middle pane , near the middle (top to bottom ) as I explained earlier... it looked just like a defroster or radio antennae wire...!

BUT , when I hear you guys describe your failure modes and looking at the one PICTURE in the earlier post... it seems that the center pane may not be made of tempered glass as it looks like it has failed in long , sharp shards.... just like a window pane that is not tempered ....and not the 'crackling' , small pieces that usually represent a bonded/tempered windshield glass or even a tempered window in a home that is less that 18 inches of the ground (building code) .

Could it be that the expansion and contraction for whatever reason & stress concentration from the window opening flange affects the center / non tempered pane and not the outer two tempered ? panes..??

andy (ajb)
 

STORMCAT

GT
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May 25, 2006
7,549
Ft. Lauderdale
Whew! when I first saw those "Red Hot Mojo" chips I thought we were going to have an explanation involving human gas pressure....

Well yes that comes into play also. Creating more internal gas pressure in the cockpit!...:lol
 

PeteK

GT Owner
Mark II Lifetime
Apr 18, 2014
2,267
Kalama, Free part of WA State
Strange. I drove about 8000 miles on my car in the two weeks driving to and from the Rally, and traveled on some pretty rough roads under construction, and at higher altitudes than in Utah. Passed 50,000 miles too. No cracks (yet). Knock on wood.
 

Xcentric

GT Owner
Mark II Lifetime
Jul 9, 2012
5,213
Myakka City, Florida
The altitude hypothesis doesn't hold water.

If the window vacuum seal is intact, by definition there is no air inside to expand with altitude (or heat).

If the window vacuum seal failed, the air inside the window will expand with altitude (or heat) and exhaust where the leak is (because it is not sealed like a snack bag). The pressure inside will equal the pressure outside.

If for some reason you made a multi-paned window with air inside and then sealed it, the inside pressure would exceed the outside pressure with altitude and/or heat, but the difference of a few psi would not matter. After all, the GT window has a constant difference of 14.7 psi at sea level.

This is why I quit engineering school. I'm already OCD.

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STORMCAT

GT
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May 25, 2006
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Ft. Lauderdale
The altitude hypothesis doesn't hold water.

If the window vacuum seal is intact, by definition there is no air inside to expand with altitude (or heat).

If the window vacuum seal failed, the air inside the window will expand with altitude (or heat) and exhaust where the leak is (because it is not sealed like a snack bag). The pressure inside will equal the pressure outside.

If for some reason you made a multi-paned window with air inside and then sealed it, the inside pressure would exceed the outside pressure with altitude and/or heat, but the difference of a few psi would not matter. After all, the GT window has a constant difference of 14.7 psi at sea level.

This is why I quit engineering school. I'm already OCD.

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My GPS gave me a reading of over 7,000 ft in Park City. All of the cars see all of the other factors on a daily basis heat road conditions twisting frames Etc . The only common denominator for all these cars that is not a normal condition on a daily basis was the elevation. For that many to break how could you not include or conclude it as a factor.. Of course you could come up with a theory about the recent solar eclipse and the reduced gamma rays changing the effect of the air molecules on all materials ..:)
 

DC-DD

GT Owner
Mark II Lifetime
Oct 26, 2010
179
PA / FL
Seems to me since all glass cracks were rear glass that it would have something to do with the heat from motor side on one side and assuming all of the cars had windows up and AC on . ( be nice to know how cold the setting) that interior side very cool that the altitude played some part . Did anyone have there widows down and no AC on and get cracked rear glass?
 

Xcentric

GT Owner
Mark II Lifetime
Jul 9, 2012
5,213
Myakka City, Florida
My GPS gave me a reading of over 7,000 ft in Park City. All of the cars see all of the other factors on a daily basis heat road conditions twisting frames Etc . The only common denominator for all these cars that is not a normal condition on a daily basis was the elevation. For that many to break how could you not include or conclude it as a factor.. Of course you could come up with a theory about the recent solar eclipse and the reduced gamma rays changing the effect of the air molecules on all materials ..:)

The only common denominator is age.

Or maybe low mileage. Or maybe high mileage. Or number of times the seat back whacked the glass. Or number of times the car was jacked by a corner.

Altitude is common for many of us and much higher than 7,000 ft. too.

Heat and cold are common. Zero degrees F and then heat the engine bay hundreds of degrees higher? The window is made to be a firewall.

I don't include altitude as a factor, because I don't know of any science to support it. Correlation is not causation. Like blaming vaccines for autism.

Anyway, it's almost as curious as gauge failures. The cause may be as obscure. Unacknowledged manufacturing defects?

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CJ428

Farm GT
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May 21, 2008
1,473
NJ
Did everyone's glass break after they ran on track. Or did some windows break before the run on track.
 

CJ428

Farm GT
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May 21, 2008
1,473
NJ
Also this was a fairly high speed track event and hitting the curbs through the chicanes would put a lot of pressure on the rear bulkhead
 

AJB

GT
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Jun 28, 2006
2,943
Bloomfield Hills, Michigan
1. my window broke on the way to the track , in the dark at 6:00 am following Jim in his 2017.

2. While on the track , ALL CARS MUST RUN with both windows fully OPEN for safety

3. yes. some run the A/C on to keep fans running full for engine temperature decrease.,, but as noted... both windows open.

andy (ajb)
 

STORMCAT

GT
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May 25, 2006
7,549
Ft. Lauderdale
I and many others have tracked our cars a lot. Most track days require you to have the windows open... hitting curbs and bumps on the track is fairly common.
 

Special K

GT Owner
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Aug 23, 2016
1,775
Franklinton, LA
What about sound/resonation? What mods were done to the cars? Maybe this played a part?


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Xcentric

GT Owner
Mark II Lifetime
Jul 9, 2012
5,213
Myakka City, Florida
Occam's razor.

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2112

Blue/white 06'
Mark II Lifetime
Occam's razor.

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:lol
 

Special K

GT Owner
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Aug 23, 2016
1,775
Franklinton, LA
Occam's razor.

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So like Vincent Laguardia Gambini once said:
I guess the f@&$ing thing's broken...


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txviper

GT Owner
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Dec 31, 2007
613
So like Vincent Laguardia Gambini once said:
I guess the f@&$ing thing's broken...


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LMFAO! Finally some science I can understand!
 

roketman

GT Owner
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Oct 24, 2005
7,994
ma.
No that's funny
 

NorthwoodGT

GT Owner
Jun 12, 2009
1,215
Michigan
another scenario: could have been a group of Cubans infiltrating your GTs with sound waves! or it just could have been you were behind Xcentric with his monstrous flow thru exhaust ! none of the above or my explanation makes much sense either way while some got cracks and some didn't. crazy