Will new windshield crack too?

[ErikH]

My windshield decided to crack while I was ascending an axle-twisting climb last weekend. I'm assuming the stress from the flexing frame/body cracked it. But will it happen again on a new windshield? Was it the polyurethane body mounts I installed? Has anyone seen this before?

 

[BluThndr71JMMY]

All of my windsheild problems have been caused by FOD -- (foreign object debris) -- small stones, gravel etc. kicked up by passing cars or semis, or gravel off construction loads, coming off and hitting my windshield glass causing a small star chip which gets super heated by the sun and then a running crack develops. If caught in time, the stopcrack guys can do a trick with superglue --real secret process -- or a bug deflector can prevent rock bits from hitting you.
Don't know about hyperflexing, which you describe.
Are you running topless? Was there any modification to your windshield frame -- new header bow & B-pillars? Recent replacement by a less than careful shop?
Sometimes I wish there was a way to fold the windscreen forward like on a jeep. Then you could tell the happy K/5-ers by the bugs in their teeth!

 

[ErikH]

No, I wasn't running topless. And the K/5 is almost totally original. Maybe 30 years of desert sun baked the glass causing it to be a little more brittle...? Very puzzling. The crack looks like a huge star crack, almost like an impact blast, but it happened in the middle of nowhere at less than 3 mph.

 

[BluThndr71JMMY]

Man, that is wierd.
I have noticed that the repop windshields are not as stout as OEM -- Surprize, surprize.
I did get a used PPG OEM windshield (w/ custom pkg trim chrome thrown in, for $100 from a "vintage recycler" (junk yard) a couple of years ago. It came off a GMC suburban 3-door '72 and I put it on my '68 stepside pickup with a new standard gasket. [sans chrome which I'm saving for the Jimmy project...] Anyway there were some little star chips which --either I didn't see or developed after the fact, but I haven't had any runs yet. I circled the pits with sharpie ink and I intend to get the superglue witchdoctors to do their thing -- I know JC Whitney sells a kit, but I don't want to mess with it.
I am concerned about the hyperflexing issue, since I too have some polyurethane body bushings to install and I don't want to turn my K/750 into a flexi-flyer!

 

[kilomanjaro]

are you rocker boxes rusted off? they are a major part of the cab support, and if they are rusted off the cab can flex alot more than if they were present. i think that if either the rockerboxes, floorpans, or windshield frame is rusted out then your cab might not be supported as well as if it was not rusty and the twist could have cracked you windshield. if your truck is rust free, i have no idea. maybe just an old windshield. good luck

 

[Steve_Chin]

PPG is aftermarket glass... Libby Owens-Ford is the original supplier of glass to GM. PPG glass is just as good as LOF glass (I like the tint better on the shaded PPG glass I have than the original shaded LOF glass on my friend's '72), but they just weren't the original supplier...

 

[BluThndr71JMMY]

Thanks, I wasn't sure. Since they came off a GMC, the glass shop guy thought it might've been factory. Hard to tell 29 years later, but then not many windshields last that long especially in the southwest.

 

[ErikH]

There's barely any rust anywhere on the vehicle, which a result of a long desert life. In fact, I re-used all the original nuts/bolts when I installed the new polyurethane body-mounts. The beast is clean. I can only guess the windshield was a cheap replacement, not original.