Windshield keeps cracking

Hello everyone,

After reading for quite some time, I thought I would post a question and see what happens.

Like most everyone, I've gone through the windshield blues (several times now :( over the years). I just installed the windsheild, put the top up and it sat for several days. After finishing up all the 1000 other things I was doing with it, I finally washed it and again let it sit. Next morning, a crack appeared, starting midway up the left pillar proceding on a 45 degree angle to the bottom rail. Grrrrrr. One thing that did change that day was that I observed that the center rod was not tight at all after installation so I tighented it. However, having done this many times over the years, I did not think that I "over-tightened" it.

So I am wondering if the top is on too tight? Can a top be too tight? I don't think it is as the hold-downs snap friendly. Can that center rod cause a crack starting at the side post?

Anyway, I know it is a long shot but thought I would see what comes back.

Spring is almost here in the northeast! :)

Ernie

I would "guess" that there is something in the left side pillar - either a screw that is too long, or something trapped that is "nicking" the windshield.

I very much doubt if the center rod, or a tight top, would cause a crack like this, however, the center rod may have helped the crack to propagate. Cracks typically are initiated by a nick or "ding" in the glass. A stone chip is the most common, but if something chips a tiny piece out of the edge, it can act as the "stress riser" required for a crack to develop.

I'll agree with Limey, when I got my car the windscreen was cracked. It was caused by the DPO using too long a screw when assembling the frame and chipping the edge of the glass.

Do you have enough packing/spacers between the car and the bottom of the side pillars, where the bolts go in.
First time I did a windscreen I used the thick plastic spacers, but didn't know about the thinner ones. After a day or two my windscreen cracked from the top corners toward the bottom, at about a 45 degree angle. First one side then the other. Only on the outside laminate on one side. This process was accompanied by many shrill cries of pain from me!
The idea of these spacers is that when you fit the windscreen to the car the bottom of the side pillars slide closely over them so that when you tighten the bolts you do not pull the bottom of the windscreen frame inward and stress the glass.
You will probably have to remove the small covers to see and fit properly. These covers are at the top of the door jam and aren't held on by much.
Most cars have the thick white plastic spacers and one thinner spacer either side. However there may be some variation. Just as long as the bottom of the side pillars are snug and won't move significantly when you tighten up. Any waterproof, reasonably hard material will do for these spacers. They are going to be hidden under the covers anyway.

This person has posted some pretty good photos of what I'm trying to describe
http://www.mgexperience.net/phorum/read.php?1,757978

Thanks to all!

I must confess that I got this unit as a unit and it wasn't cracked for the PO. Sooooo, I am leaning towards the spacer suggestion. I must confess that I didn't give that a 2nd thought. I have the larger ones in and don't really know if there is any additional gap that needs to be filled.

Shouldn't this have cracked upon initial tightening or VERY Soon after? This thing sat for several days. Now upon reflection, I really wasn't climbing in and out, up and down slamming the doors after the initial installation.

Off it comes - maybe not for a while as spring is here and I might just live with it as I did for the entire summer last year with the last one I put in (groan). I just may break down and design a modern replaceable glass windscreen. Truth be told... I was hoping that someone else would and I would be first, in possibly a long line, to buy one.

Thanks everyone,

Ernie

I've got the same crack. It happened about two weeks after I put in a new windshield. A couple of things might have happened. One, it got quite cold the night it cracked. If the windshield was in too tight, I suspect the frame might have contracted just enough to crack it. Of course that really shouldn't have happened if the windshield was in right. Which brings me to two. I never did check the size of the windsheild against the one that I took out. I have read on here that replacement windshields may need some shaving since they are not being made quite as carefully as before.

Strees crack, Hot and cold brought it out!!!!!!! Mine did the same first time out on the road. Cold night, next morning cracked.

photo.
I used some old serpentine fan belt as spacers, that happened to be about right. I was going to use ply wood or a a stack of bits of plastic ice cream container until I noticed the coincidental thickness.

Hi Peter,

Great photos and good idea. Did the crack happen because it wasn't shimmed right or just the temp changes. I am suspecting the former in conjunction with the latter.

Thanks

When I bought the car It did not have the thinner shimms at all and only had the white spacer on one side. With the covers on this was not apparent, infact I didn't even know about either spacers. The windscreen was loose of course. First thing I did was tighten up the bolts. It cracked of course.
When I replaced the glass I just went and got another white plastic spacer, didn't know about the thinner shims. The guy behind the counter didn't say anything. Initially it was OK. A certain amount of prideful stepping back and admiring. A day or two later the first crack appeared on one side, then a while later on the other. Slowly they grew. The wind screen is actually quite flexible for a short while. However if the glass is stressed when you slam the door or hit a bump, or even as you suggest, gets particularly hot or cold, it's going to fracture.
As you can see all I did was wedge something into the gap before I tightened up. I then put the center screw in. At some stage I'll dig them out of their box and put the covers back. A couple of self tappers at the top and I'll rely on the door rubber to keep the bottom located.

Do we have any pictures of the spacers in question? I had the windshield in my B replaced by a shop that supposedly knew what they were doing.

First night it got kinda cold and warmed up during the day I had a crack coming from the top passenger corner headed towards the bottom driver side corner.

I called to ask them to look at it. They sent someone who quickly decided it was a rock that caused it, and not a stress crack, then left. I am not satisfied by this because the only "chip" in the crack is very minute and the crack occurred while the car was parked in a garage.

It was fine in the morning, but when I went to drive it home in the evening the crack was there.

Hagerty paid for the windshield replacement, but I don't believe they should have to fork out for another replacement because of either installer error or defective glass.

Wow! Hagerty pays for windshields? I had no idea.

Better luck with the next try!

Just maybe,

There are several qualities of windows on the market for mgb some going for $100.00. I have put some of these in only to have them crack. So from then till now I have got the windshields from Moss they are expensive $300.00+ but they are tough and match the original. Cheaper in the long run. Installing windshields is not a lot of fun.

following topic - gotta do a windshield soon