Cracked rear glass

[TO AWSUM]

Mine cracked at the track also. Started with multiple 1 inch breaks in lower right corner behind driver then single crack across center of window. One person told me it could have been caused by sliding driver seat back. I don't slide back roughly tho.

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[B.M.F.]

The rear windows list for 1000.00 and are 660 dealer cost. super easy to install. Kinda crazy to hear about that many in one weekend breaking tho..

 

[Kayvan]

Long shot....A/C

In Miuras the dash mounted circular A/C vent cracks the windshield if left in open in direct sunlight.

My left a/c louvre makes my SS watch ice-cold while driving.

Vents aimed to rear with Cold glass and rear firewall heat?

 

[NorthwoodGT]

Long shot....A/C

In Miuras the dash mounted circular A/C vent cracks the windshield if left in open in direct sunlight.

My left a/c louvre makes my SS watch ice-cold while driving.

Vents aimed to rear with Cold glass and rear firewall heat?

Anything is possible at this point. Now I know why I had 2 requests for back glass yesterday. I don't sell the glass due to shipping issues. the last 3 we shipped got cracked in transit even with incredible packing. Part number is 4G7Z-6342006-AA. dealer cost is $605.03 with SRP $1008.37. The Ford dealer will show no stock in the warehouses because it is a supplier direct shipment from Carlite to the dealers. order from your local dealer to make sure it doesn't get broke. Also check it out carefully for any chips or cracks before paying for it because they will not take back glass.

 

[AJB]

At this point, I am considering just leaving it cracked. !
Ajb (andy)

 

[2112]

Shelby, did you make any modifications to the window frame when you replaced those other pieces of glass?

 

[Beach-GT]

Sounds like an altitude problem somehow. This epidemic seems to be related to Utah. Down here at sea level I do not think we are having this problem.

 

[roketman]

Not an Altitude problem ,but rather an attitude problem.
I rest my case on the fact it happened to Rick Hanson!

 

[Specracer]

One vote against track use, at least with my car / frame. Note sure if anyone used their car harder than me at Miller, I burned 3 complete tanks of fuel (got gas 4 times), and saw lateral g loads just over 1.5g's (assuming I'm reading data right on new to me data analysis). I got my car back late yesterday and checked to see if my window was in tact. It is.

 

[Xcentric]

Rally attendees came from every climate and elevation. The only common factor is every failed window is 11-12 years old.

The glass is installed with a urethane adhesive. There is no surrounding gasket.

I will discount altitude as a factor. The difference in pressure between sea level and 10,000 feet is about 4 psi. The window is triple pane and vacuum sealed. Pressure change with altitude is negligible relative to the vacuum and, in any case, would affect only the outer panes. Several (if not all) failures were of the middle pane.

My hypothesis: The urethane adhesive hardens with age. This is true of all organic adhesives. Loss of flexibility can transmit vibration/twisting stress directly to the glass.

Anyone replacing the window, please report on the condition of the adhesive.

I'd look at alternatives to urethane. Maybe silicone? I'd also make sure the pinch weld is flat. Grind down any bumps (although the manual cautions against "scratching the pinch weld"...what is that about?). Use a thick bead of adhesive. Ensure there is no possibility of metal to glass contact.

Maybe look at fitting a real window gasket. I don't know how critical the thickness is.

 

[2112]

Good suggestions.

Just one word on silicone adhesive. It can be insanely hard to remove in the future.

 

[STORMCAT]

Part of the answer lies in this bag of chips. This came from sea-level environment and in Park City it was about to burst.

I think the widespread breakage could be contributed to three things. Deteriorating sealant. Pressure loss or pressure drop in one of the panes and the altitude air pressure differential causing expansion , compounded expansion from heat and possibly frame or structural twisting...

 

[STORMCAT]

The rear windows list for 1000.00 and are 660 dealer cost. super easy to install. Kinda crazy to hear about that many in one weekend breaking tho..

it's the mid glass.. from my understanding it's not that easy to replace..

 

[2112]

I would have guessed all 3 pieces come assembled as a single unit. No?

 

[Special K]

Part of the answer lies in this bag of chips. This came from sea-level environment and in Park City it was about to burst.

I think the widespread breakage could be contributed to three things. Deteriorating sealant. Pressure loss or pressure drop in one of the panes and the altitude air pressure differential causing expansion , compounded expansion from heat and possibly frame or structural twisting...

Are u going to eat those? I'll take'm if u don't want'em...


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[Xcentric]

Part of the answer lies in this bag of chips. This came from sea-level environment and in Park City it was about to burst.

I think the widespread breakage could be contributed to three things. Deteriorating sealant. Pressure loss or pressure drop in one of the panes and the altitude air pressure differential causing expansion , compounded expansion from heat and possibly frame or structural twisting...

Your snack bag is not vacuum packed, but it is sealed. Not a valid analogy.

I do not see the logic of pressure loss. Pressure differential does not cause expansion of window glass or the surrounding frame.

The window has 14.7 psi pushing on the outside and zero psi on the vacuum side. All the time. At altitude, the outside pressure is less (10-11 psi in the high mountains). Therefore, even less stress than at sea level.

If the vacuum seal fails, there will be less stress because the pressure will be equalized on the inside and outside.

Plus, if the vacuum seal failed, you'd see condensation inside the window, because moist air would enter.

I don't know the composition of the window glass. I assume it is tempered, which can withstand thousands of psi. Change of atmospheric pressure with altitude is trivial.

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.

 

[Cobraguy]

Not an Altitude problem ,but rather an attitude problem.
I rest my case on the fact it happened to Rick Hanson!

Ron.....what took you so long?!?!

 

[STORMCAT]

Your snack bag is not vacuum packed, but it is sealed. Not a valid analogy.

I do not see the logic of pressure loss. Pressure differential does not cause expansion of window glass or the surrounding frame.

The window has 14.7 psi pushing on the outside and zero psi on the vacuum side. All the time. At altitude, the outside pressure is less (10-11 psi in the high mountains). Therefore, even less stress than at sea level.

If the vacuum seal fails, there will be less stress because the pressure will be equalized on the inside and outside.

Plus, if the vacuum seal failed, you'd see condensation inside the window, because moist air would enter.

I don't know the composition of the window glass. I assume it is tempered, which can withstand thousands of psi. Change of atmospheric pressure with altitude is trivial.

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.

Let me explain it to you rocket scientist man.:biggrin There is less external pressure on the glass due to the altitude. Heating of the glass panes and heating of the air inside of the panes cause expansion.. with a lower external force holding the glass ..pop glass breaks..

 

[Special K]

Go get'em Stormy


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[nota4re]

Whew! when I first saw those "Red Hot Mojo" chips I thought we were going to have an explanation involving human gas pressure....