how structural is the windshield?

[Kevinma255]

Have an 89 xj. Planning on building a cage eventually but just had the winch cable snap back and shatter the windshield today. I do a lot more than I should with the jeep so Twist and bend is what I am worried about. I dont do much off camber, it scares me. Think I will be ok to throw a sheet of plexi glass in as a mud deflector untill I build the cage or am I going to twist it by doing that?

 

[JJacobs]

Warning, anecdotal information:

A glass guy told me up to 40 percent of a unibody car's upper structural strength comes from the windshield. Something about wrecked cars folding like the proverbial taco after some shop ghetto-glued the windshield in with silicone..

 

[96XJ_4.0]

It's not at all.

It's glued in with silicone.

 

[winterbeater]

x2 - no structural support from the windshield. To do so, it would have to be rigidly mounted. If you wanted to support that area, You could put crossbraces in the windshield opening. Like threaded rod and turnbuckles.

 

[ehall]

It provides some resistance but it wont hold the car together. It's like the doors in that respect.

 

[JJacobs]

From http://www.windshieldexperts.com/internal.aspx?catid=6 :

9. Did you know that proper windshield installation is as important to your safety as safety belts, air bags and anti lock brakes?

Ans: That's right! Today, auto glass is more than just a shield to protect the driver and occupants from wind, weather and debris, windshield contributes upto 40% of the structural strength of the car. Now the windshield also keeps you and your family from being thrown from the vehicle in case of a collision.

Proper auto glass installation is the key to your safety. There is a right way and a wrong way to install auto glass. Auto glass installation requires a very strong yet flexible adhesive to bond the glass to the vehicle frame. This adhesive must have great strength to withstand the pressures put upon it in the event of a collision. The most widely used adhesive is called "automotive grade urethane".

Insist that a strong automotive grade adhesive be used to bond the glass. Don't let the glass be installed on corroded metal.

Urethane is a far cry from silicone.

 

[Kevinma255]

should have been clearer. this is an off roader only. Trailer it to RC and home. So from what I am understanding I should be fine with just the plexi for light running. I will have the cage for stability before I do anything hard. Will be out there for my bachelor party in a month or two and dont want to build the cage yet. no money.

 

[96XJ_4.0]

From http://www.windshieldexperts.com/internal.aspx?catid=6 :

9. Did you know that proper windshield installation is as important to your safety as safety belts, air bags and anti lock brakes?

Ans: That's right! Today, auto glass is more than just a shield to protect the driver and occupants from wind, weather and debris, windshield contributes upto 40% of the structural strength of the car. Now the windshield also keeps you and your family from being thrown from the vehicle in case of a collision.

Proper auto glass installation is the key to your safety. There is a right way and a wrong way to install auto glass. Auto glass installation requires a very strong yet flexible adhesive to bond the glass to the vehicle frame. This adhesive must have great strength to withstand the pressures put upon it in
the event of a collision. The most widely used adhesive is called "automotive grade urethane".

Insist that a strong automotive grade adhesive be used to bond the glass. Don't let the glass be installed on corroded metal.

Urethane is a far cry from silicone.

"Automotive Grade Urethane" made me chuckle.


Did you notice the website's name....windshield EXPERTS...as in these people preform tests and develop real life results...I doubt it?

That little part up there about being strong AND flexible proves the lack of rigidity of a windshield.

I have heard this before in the past. If my memory serves me right, I believe the point of that rant you quoted was that A WINDSHIELD CAN BECOME DISLODGED IN A FRONT END COLLISION, subsequently leaving the vehicle at speeds near that of the impact. ie.: 70mph airborne windshield

Care to explain how silicone is a "far cry" from urethane? Cause I'm just not seeing it.

 

[Kevinma255]

silicone is different from urethane. It is like elmers glue and Crazy glue. Silicone is more of a gasket/sealer and urethane is more of a bonding agent/sealer But I knew that. I just did not want to cork-screw my jeep because I thought I new something and was wrong. It happens more than I would like to admit.

 

[JJacobs]

Have you ever glued a window in with urethane? It sucks. There is a reason the window installers have motor-driven urethane dispensers, that stuff is thick! I guess it helps a lot if you heat it up.

If you don't like the reference look around some more, that was near the top of the Google hits. The OP's question: How structural is the windshield? Answer: very. Do some research.

 

[96XJ_4.0]

silicone is different from urethane. It is like elmers glue and Crazy glue. Silicone is more of a gasket/sealer and urethane is more of a bonding agent/sealer But I knew that. I just did not want to cork-screw my jeep because I thought I new something and was wrong. It happens more than I would like to admit.

So that explains it. rofl

You also might want to tell NASAs JPA that they messed up. Somehow urethane is better now since they built the space shuttle. Seems they might not Know of this drastic difference.
http://findarticles.com/p/articles/mi_qa3957/is_200405/ai_n9457726/


Here is some actual facts presented by DowCorning.
http://www.dowcorning.co.kr/ko_KR/content/publishedlit/63-1015-01.pdf?DCWS=urethane&popup=true



Were talking peas and carrots here.

 

[JJacobs]

"Automotive Grade Urethane" made me chuckle.

Why is that?

This company sells it: http://www.daius.com/polyurethane.htm
Here's some 3m stuff, apparently it meets the OE specs too http://www3.3m.com/catalog/us/en001...upport_3_0/command_AbcPageHandler/output_html

 

[96XJ_4.0]

So where fo I find "tank grade urethane"?

 

[joe_peters]

From http://www.windshieldexperts.com/internal.aspx?catid=6 :

9. Did you know that proper windshield installation is as important to your safety as safety belts, air bags and anti lock brakes?

Ans: That's right! Today, auto glass is more than just a shield to protect the driver and occupants from wind, weather and debris, windshield contributes upto 40% of the structural strength of the car. Now the windshield also keeps you and your family from being thrown from the vehicle in case of a collision.

Proper auto glass installation is the key to your safety. There is a right way and a wrong way to install auto glass. Auto glass installation requires a very strong yet flexible adhesive to bond the glass to the vehicle frame. This adhesive must have great strength to withstand the pressures put upon it in the event of a collision. The most widely used adhesive is called "automotive grade urethane".

Insist that a strong automotive grade adhesive be used to bond the glass. Don't let the glass be installed on corroded metal.

Urethane is a far cry from silicone.

First, I did not follow the link and read the entire article.

However, as I feel completely able to speak entirely from ignorance, I want to add a little to the discussion--what about my CJ2A and FJ40? I really don't think there was ANY contribution from the windshields in those vehicles as the frames would fold like a TACO.

Now, when where current roll-over standards adopted? What years does that 40 % figure apply to?

Ok, back to your regularly scheduled thread...

 

[JJacobs]

Come on, Joe. :twak:

One's a unibody, the others have frames. Far different construction, in fact apples and oranges.

 

[SC Rednek]

I don't know about the structural importance of the windshield, so I won't get involved in that. However, unlike real glass, plexi scratches very easy, and is also very flexible. So as soon as it gets mud on it, the windshield wipers won't make hard contact, and where they do it'll just scratch. I'd rather have no windshield at all then one of plexi.

Any other peice of glass, plexi is fine. I have a sheet of plexi as my rear windshield but I unplugged the wiper when I put it in. Difficult to seal though and it tends to flap in the wind. I know other people using it as side windows without problems.

 

[joe_peters]

Come on, Joe. :twak:

One's a unibody, the others have frames. Far different construction, in fact apples and oranges.

Put away the can of whoop-a**!

Went and read the article.

Did you know the Windshield Experts are in India? Cute little map of all their locations there.

Seriously, federal roof-crush standards were first established in 1973, and that standard was pretty simplistic. I am genuinely curious about the crush standards. I'm fairly certain that manufacturers would be trying to get extra strength from something that already exists on a vehicle, like a windshield, rather than adding more metal. I was hoping someone had some engineers insight into auto glass design as a structural component.

So, stop beating me like a red-headed step child on a Saturday night!

 

[1990heepxj]

ok so tell me wouldnt a windshield just crack when flexing the body if it was nearly half the support? theres no way that all the metal of the frame and body are only 60% and one rectangle of glass makes up the other 40%. it just doesnt compute right to me...

 

[NW-ZJ-SCOTT]

ok so tell me wouldnt a windshield just crack when flexing the body if it was nearly half the support?

Yes. my mazda has a TSB because the windshield would crack due to body flex

 

[joe_peters]

Yes. my mazda has a TSB because the windshield would crack due to body flex

Just read in the newest JP Magazine their take on the XJ's leaking windshield/rusted floor pans that body flex is breaking the windshield's seal.