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Exploding Rear Window - another victim

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Old 12-14-2007, 07:58 PM
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Gbag
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Default Exploding Rear Window - another victim

If there is anyone lonely enough to be tallying victims of the mysterious "exploding rear window phenomenon" aka ERWP, add another to the list.

Situation: Driving straight, on the highway, 60 mph. Sunroof open only.
Action: Window suddenly exploded with a loud bang, no impact evidence.
Reaction: WTF!
Outcome: $200 deductible, 5 day wait, hard-to-find factory glass, $1440 total (885 just for glass) included all new seals, porsche adhesion kit, done by a trusted quality resto shop I've worked with before. Had paintless dent repair dial in a few spots at the same time...... not bad, but a hassle......

The mystery continues.
Old 12-14-2007, 08:32 PM
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Bruce SEA 993
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Yikes...bad deal. It is kinda rare though.

If I recall, the manual limits the sunroof to a max of 50 MPH. I wonder if this is why.

Hope you are back in the saddle!
Old 12-14-2007, 09:56 PM
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Matt Lane
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50 mph max with the sunroof. Really?

Can anyoine else chime in and save me from digging out my manual... this doesn't sound right. And if it is right, it certainly doesn't sound good...

Old 12-14-2007, 10:19 PM
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lumpy
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50 mph...not good. I drive much quicker on the freeways with my sunroof open.
Old 12-14-2007, 11:50 PM
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davesnothere
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Originally Posted by lumpy
50 mph...not good. I drive much quicker on the freeways with my sunroof open.
Ditto. Although most of the time if the sunroof is open, I have the windows either down or cracked. I can definitely feel a difference in the cabin pressure -- wonder if this is behind the ERWP?

- Dave
Old 12-15-2007, 12:13 AM
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95C4VanIsle
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My manual states "not to exceed 62 MPH. The wind force may cause damage to the roof headliner or mechanism." Nothing mentioned about exploding rear windows.
Old 12-15-2007, 12:24 AM
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2ndof2
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Thats crazy stuff! I always hear what sounds like the seals around the rear glass flexing when I have to enter or exit driveways at an angle. I half expect the window to explode whenever this happens. Has anyone determined if having a lowered car with stiffer than stock suspension adds to the problem?
Old 12-15-2007, 12:26 AM
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Scott 1996 993c2
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Bummer!

Hmmmmm ... one of my cars has no sunroof ... the other 3 have no roofs.


Scott
Old 12-15-2007, 12:31 AM
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Ed Burdell
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I must have missed that section of the manual - heck, my sunroof is always open, and 62 mph is typically a distant memory...now I have something else to worry about?
Old 12-15-2007, 06:28 AM
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Garth S
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Originally Posted by Scott 1996 993c2
Bummer!

Hmmmmm ... one of my cars has no sunroof ... the other 3 have no roofs.


Scott

I love innovative solutions ....
Old 12-15-2007, 10:04 AM
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David 23
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When my window exploded it was sitting in the garage. Open sunroof while driving had nothing to do with it.
A front strut brace and BK harness truss bar helped reduce body flexing and window frame creaking dramatically. I installed these after losing the window.
Old 12-15-2007, 12:55 PM
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AX993
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Mine exploded while exiting a gas station this past year. Sunroof closed, but this is the first I've heard of a speed limit on the sunroof !! There's a lister Down Under who has had several rear windows explode (on the same car) so I'm not sure about how rare it is.
David 23, I also have a front strut brace, but hadn't thought about trying a harness truss bar to limit body flex near the rear end. Sounds like a good idea !
Old 12-15-2007, 01:18 PM
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If mine ever explodes, I'm going to think seriously about putting in a lexan window. Those don't explode.
Old 12-15-2007, 01:21 PM
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David 23
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Originally Posted by glenn '88 944S
Mine exploded while exiting a gas station this past year. Sunroof closed, but this is the first I've heard of a speed limit on the sunroof !! There's a lister Down Under who has had several rear windows explode (on the same car) so I'm not sure about how rare it is.
David 23, I also have a front strut brace, but hadn't thought about trying a harness truss bar to limit body flex near the rear end. Sounds like a good idea !
I use the car 95% track, so the truss was needed for the harness. However the added benefit was the reduced flex. It was very noticeable.
Old 12-15-2007, 03:08 PM
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I've read many post on the exploding rear window, and I having some experience in the glass industry, I thought I might be of some help, although my back glass is plastic.

The back glass exploding problem is not just with 993's or Porsche's IMO. I've seen tempered glass (Back glasses, door glasses ect...) break on many different cars for no apparent reason. We sold and replaced many in Ford, Chevy, Dodge, Toyota, and just about all the mfgs. I've also seen a guy use a sledge hammer on a Camaro back glass and nearly kill himself trying to break it. The hammer just keep bouncing back until he hit it near a corner and it finally exploded. We replaced more Camaro / Firebird Back Glasses than any (talk about a problem, these cars had a major issue with the glass breaking). The strength is in the center of the glass. I've also broken one just taping the edge with a small screwdriver. I cringe anytime I see someone near the edge of a door glass with a metal object. The edge is the weakest point. I've also seen a guy take a door glass and throw it like a Frisbee across a parking lot and it was only scratched. And I've also taken a back glass from a pickup and set it on a table and nearly bent it over 90deg. and it didn't break. And I've seen a guy walk out of our shop in the winter, going from 70 deg. to say 15 deg. with a new door glass under his arm and it exploded before he could get to his car.

So tempered glass is very strong and can be very flexible, but it can also explode unexpectedly due to many different factors.

Just my $0.02.
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