The Stovebolt Site Forums The Shop Area General Truck Talk Nearly new window cracks for unkown reason- any body else?

Last fall or so, I changed out a window that had been cracked when I got the truck 4 years ago. I replaced it and the drivers side window that was fogging at the edges from age, also. Anyway, today when I rolled up the passenger window, I found a crack. I got these from Classic Parts, and I thought since they use two ply glass as the old ones did, they'd be good for another few decades if I treated them right. This truck is my daily driver and the door is solid and gets minimal use(Grocery trips, the dog sometimes), but nothing much. It's even got a new rubber door seal since last fall, so it's not banging on anything. Is this a common problem with new glass? I mean, the glass is priced right, but I'd rather pay more and not have to do the re-work. Sort of like the time a buddy told me how much he loved Auto Zone and their 'life-time warranty' after he'd taken back 3 starters that failed, in a row. I commented that they may pay for the bad parts they shouldn't have sold him, but who pays for all that time your under the hood cussing for having to do the same job twice. Or 3 times. Is it best just to find a local glass guy to duplicate these windows, or can they even get this type of glass in the states anymore? Thanks for any feedback on this.

I reckon this is on your '51, right?

Glass is tempermental and can crack just by looking at it. That being said, the crack could have happened when the door got shut. My passenger door window did that in the lower rear corner after shutting and it wasn't a big crack, maybe 2 inches long and in a sideways sorta circular V with the point of the V going forward. Is the crack a big or small one? Myself, it's always best to find a local guy if you can, for obvious reasons.

Final a local glass man that has been doing windows
for 30 years and ask him about possible causes.

Years ago I had a windshield crank in the middle
going straight up. Friend owned the car first. So
I told him and he said he had the windshield crack
that way before.

When the glass man was installing the new windshield
I told him that this was the second windshield that
cracked this way on the same spot on this car.

Glass man was glad I told him. For he now could adjust
things to prevent this new windshield from cracking.
I don't remember what he did but the new windshield
did not crack. Jeffrey

Laminated glass is pretty tough, it shouldn't be cracking no matter who makes its. Look at the mounting rail it sets in or mounting holes, and make sure there is no points sticking out or bent pieces. When glass is put under tension, it will crack at some point. When we find a crack in glass on school bus fleet from stress, it's usually a weld not ground down or foreign material stuck behind it. We had two full length windshield crack due to a small weld bead in one corner.

Here is a picture I took last night when I found it after rolling my window up (it had been down all day-sorry for the not so great photo). http://pic20.picturetrail.com/VOL1373/13685773/24611517/413285852.jpg

cablesmith, it's in about the same spot as yours, it seems. I know I've got a loose connection in my drivers door (bottom window rear window rail) that I've got to get in there and weld tight, and I was more worried about something like this happening over there, but until I take this apart, I don't know what could have happened. Just wondering, does anybody know if the glass coming from CP, LMC, etc. is tempered? My truck is parked with the passenger side to the south (one way street here), and this may be the first time it's gotten over 80* since I put it in. Just curious if this is a heat thing from the inside of the door of a black truck (??)

I'm not positive but if memory serves me correctly the window is bedded in a U shaped channel & the channel is connected to the hardware that moves the window up and down? If this is correct it was common back in the day when I was a body man for find new replacement windows crack if the channel wasn't perfectly free of glass fragments from the old window when the new window was bedded in the channel. Auto glass is remarkable robust in side on contact but quite fragile along the edge. The smallest fragment of broken glass coming into contact with the edge of the glass with a surprisingly small jostle can cause new glass to crack.

My money is on that detail right there.
With the glass held tight in the fuzzy channels at the top and at the wing vent channel, but loose at the rear corner, a single hard slam of the door (by a greenhorn passenger) could crack the glass.

Most tempered glass is thinner then laminated, and tempered glass does not crack, it usually explodes!

Showme,you say the bottom of the rear glass guide channel is loose and requires welding,the rear should be screwed in or is it in fact the mounting tab that's come off the channel allowing it to move inside the door?
Your picture is a little misleading,it does have vent wings right? (At least a '51 should have).
Shutting,or slamming the door with the glass in the open position can and will cause sufficient movement or flex to do this.

As you've found out,laminated glass does not deal with flex very well and personally i've never been a fan of it in doors but the factory used it for decades without issue which for me,certainly points to a problem inside your door.

Tiny- I said the loose rail is on the drivers side. The passenger window is the one that cracked. I was more worried about the drivers side because I haven't welded it yet. Carl, same there.

Joe H- You're right. I guess I was just assuming that any glass stamped/etched, as American glass usually is (my old windshield, for instance, still has it)is tempered.

jb50-It's the mounting tab that I'm assuming was spot welded in place. I've had it opened up and looked in there. it's a mount with two small legs that were at one time spot welded. And, yes, I guess I'm now "in tune" with the idea that laminated must not hold up against hard closing real well. Strange thing is, I've closed those doors the same way for almost 4 years. I'll have to take a close look inside the door and see if anything is out of line.

You're missing my point. The side you replaced is irrelevant.

Sorry showme,I picked that up wrongly too.

Joe H- You're right. I guess I was just assuming that any glass stamped/etched, as American glass usually is (my old windshield, for instance, still has it)is tempered.

Just to correct you,your windshields will be laminate (double layer of glass with an interlayer),the only tempered glass (single layer) on an AD cab would be the rear corner glass. (If it's a 5 window)

jb50-It's the mounting tab that I'm assuming was spot welded in place. I've had it opened up and looked in there. it's a mount with two small legs that were at one time spot welded. And, yes, I guess I'm now "in tune" with the idea that laminated must not hold up against hard closing real well. Strange thing is, I've closed those doors the same way for almost 4 years. I'll have to take a close look inside the door and see if anything is out of line.

As previously mentioned I thought the crack and loose channel were in the same door too,but as you say,an internal examination of the passenger side won't hurt,something's definitely amiss.
I'm not sure how your run felts are attached inside the door,some people choose to use small countersunk screws,if that's the case make sure there are no exposed/raised heads that could contact the glass edge,again,laminated glass hates that.
More so than in the 50 and earlier doors that have a metal frame around the one piece drop glass that would effectively protect the edges.

Showme,one other thing to check.
IF you remove the offending glass,check where the crack starts from,a badly ground edge with any nicks can create stress risers and subsequent cracking even if everything's correct inside the door,a heavily shut/slammed door could be sufficient to cause failure.
It's entirely possible the glass was supplied with a small defect.

Had a similar issue on the driver's side. There is a rubber button that bumps the glass just aft of center when your window is rolled down. If your window channels are not secure, the glass will bounce off that rubber button and crack. If you don't have the rubber button anymore, you will probably crack the glass just driving it with the windows down.

My doors are pretty rotten, and after three rounds of JB-welding the channels and replacing cracked glass, I had some polymer sheets cut. Slam the door as hard as you like, my door "glass" is unbreakable.

I had a similar problem. I replaced glass in both doors. It was the first time I had done this. It sounded simple. I don't know if I purchased the wrong thickness setting tape, but it was extremely difficult getting the new glass into the channel. I successfully completed the install. The next day I took the truck on a 60 mile drive. It was warm out and I drove with the window down. When I arrived I rolled up the windows. The new glass on one side had a crack all the way across the window. I have no doubt the cause of the crack was me. I am sure I stress the glass too much while I installed it. I probably damaged the edge and the vibration from the drive expanded the crack. Have you ever seen a small crack in a windshield and pressed your finger against it only to see the crack expand? I have not replaced the glass yet but when I do I will be getting the replacement glass from classicparts.com. They have the option to buy the glass with the bottom channel already installed. As far as I am concerned it is worth the extra money.

No, I got the point. What I didn't mention is that when I replaced the old glass, I not only cleaned the channel, but also wire wheeled it with my 4 1/2" grinder, then used 3M adhesive remover to clean it, then inspected it. I used new rubber/cork imbedding tape from Classic Parts to install it with, and I've done both windows (the first one, I did twice when I accidently put the glass in backwards, which needed another new pane it was set in the rail so well, I had to crush it to get it out. The glass, that is, not the rail.) I've read the shop manual, asked questions here and thought it out before I even started the first one. You have a good point with what you're saying. But you are assuming that I didn't know or do what was necessary. It was as clean and straight as new when I installed it, and it lasted all fall and winter without any problems. But thanks. Lee

Not assuming anything Lee. Just bringing up a potential cause for breakage that I've seem before.

"I used new rubber/cork imbedding tape from Classic Parts to install it with, and I've done both windows (the first one, I did twice when I accidently put the glass in backwards, which needed another new pane it was set in the rail so well, I had to crush it to get it out. The glass, that is, not the rail.)"

I hate it when that happens. I did it once, and, like a fool, I almost did it twice.

I am more surprised that all of these flat glass windows don't break every time we slam the door with the window down, than I am that yours broke. Flat glass has no inherent strength compared to curved glass.
I have a question for you. When the window is rolled down, is the glass excessively sloppy or exceedingly tight? You would have to take of the cardboard panel and/or lower hinge cover to check that. Sometimes the bottom of the wing vent support gets abused/twisted when that nearly-impossible-to-get bolt gets rusted solid and someone ham-hands it to get it loose.
Carl

I think I may have figured out the cause of this. My windlace on the passenger side is and has been in bad shape since I got the truck. The PO must have replaced the drivers side, because it doesn't look that bad. I actually bought new material for these when I bought the door seal last year. I've replaced both the door seals this past winter, but the passenger door windlace had a piece break off a few months ago, it's in such poor shape. (The stuff looks to me like either its had solvent sprayed/wiped on it, or like it was heated with a torch, or something. I don't know if you can see from the pics, but it looks 'boiled', as when heat or strong chemicals get on rubber. Anyway, since the crack is at the spot that the missing piece is at, maybe this is what caused it. It's time to get that old stuff out and the new one's in!! What's everybody else think?
http://pic20.picturetrail.com/VOL1373/13685773/24611517/413291170.jpg http://pic20.picturetrail.com/VOL1373/13685773/24611517/413291169.jpg http://pic20.picturetrail.com/VOL1373/13685773/24611517/413291173.jpg

The windlace should have no impact on door glass, or even how the the door closes tightly or not. It is there just to keep out additional wind from getting through.
Carl

Just remember......crap happens. The "new" passenger window on my 37 or about 5 years suddenly cracked when my sister in law shut the door. Yep, all new stuff and never a problem and it still cracked. Didn't change anything but the glass and here, 10 years later and many "slammings" by a few un-respectful idiots and it is still just fine.....it happens Showme!!!

Went out and rolled my window up the other night expecting rain, and the window is now cracked in multiple places on the lower front corner and a few have spread all the way to the top and from the initial crack up to the top in the rear of the window too. Have one ordered with setting tape and some new bumpers, but I'm going to find a local glass shop and have them use the new one for a pattern. I guess the foreign glass is untempered, or is just junk. http://pic20.picturetrail.com/VOL1373/13685773/24611517/413389677.jpg
http://pic20.picturetrail.com/VOL1373/13685773/24611517/413389676.jpg

You can run around all over the place to a "glass shop" if you want to. If it says made in America, it is made by a Chinese Co. operating plants in America. Same quality as made in China or Mexico or Canada. PPG has plants all over the world. You are going to pay more for the same thing and if it breaks, they will blame you. So figure out what is braking the glass. It's not the glass. Worn mechanism, metal touching glass, wrong tape, loose window, tight window, thermal coefficient of expansion of materials, crooked wind up. It is mandated to be safety laminated glass. It will crack or explode but hold together. Just curious: Why are windows always down and then you notice crack when rolled up? Logic says it's being cracked by a metal piece of structure hitting it while it's down. Tapping it as you drive. Or, as said, not held correctly while down. Keep the new ones up until you figure it out.
Made in the USA
Remember what Einstein said about insanity.

Wow. Didn't know about the Chinese glass market. And the company name-Fuyau (Maybe that's a mis-spelling of what they really mean- FuYou!)
Anyway, I leave my windows down because it's hot. This is my daily driver, so I leave them down in the summer unless it's calling for rain. I was wondering if the heat on the black door, which faces the south when parked on our one way street, maybe heated got it hot enough to fracture(?). This is the first summer it's been in. But I agree, there must be something wrong in there because the window I replaced last fall was cracked in the same rear lower corner. The tape is what Classic Parts sells. The regulator works great. The window moves up and down easily. When the new glass and tape come in this week, I'm going to open it up and take a good look to see what might be wrong. I'll keep you posted. Thanks for the ideas, too.

Something is binding the glass or is loose causing the glass to get banged around.
There is a bolt which holds the bottom of the wing vent window divider/track to the door. This bolt is prone to rust. Since it is prone to rust, attempts to remove it often causes twisting of the track. This could cause a stress point for your glass.
You will have difficulty seeing this without removing the wing vent assembly.
If this bolt is missing or loose, your glass will get banged around.
Carl

Just to clarify.

Laminated glass and tempered glass are very different animals.

Standard laminated glass is simply two sheets of normal float/plate glass,which is not tempered in any way with a polycarbonate interlayer creating a three layer sandwich,that's why it can still be cut to shape with a normal diamond tip cutter.

Tempered a.k.a. toughened glass however is a single sheet of float which starts life in much the same way,but once cut to shape and the edges ground it would then go through an additional process in which it's heated to a high temperature and is then cooled rapidly with air jets creating a surface tension in the glass,that's why when it does break it almost 'explodes',it does however remain a single layer.

The theory being small fragments in the event of it breaking in an accident will do you less physical damage than big shards of standard plate glass.
Once this process has been done it cannot be cut.
If you look at a tempered glass with polarised sun glasses you can sometimes see the stresses.

Laminated glass on the other hand will absorb impact and crack but stay whole relying on the interlayer to provide integrity.

Fwiw a 1/4" thick tempered glass will easily support my 200+lbs weight,a laminated glass of the same thickness wouldn't.

Jock -- Just curious as to how you might have acquired this particularly interesting little gem of knowledge ... Did a barley beverage of some sort serve as a catalyst/accelerant to the learning process here??

No alcohol was involved John as I was working at the time.
I was demonstrating the difference between the two types of glass to a trainee in a less than scientific way.

We had a scratched front door glass from a F*rd Mondeo rescued for the glass recycling dumpster which has a compound curve,I placed it facing curve upwards on two wooden blocks on the shop floor and actually managed to invert it with the center nearly touching the ground,a deflection of nearly 3" and when I stepped off it literally bounced back into shape but didn't shatter.
I have to say I was suitably impressed myself.