Mystery shattering rear glass

[puma90]

Driving along a bitumen road at 35km/h in my MY10 D90, no bumps and pop the rear windscreen completely shatters. No impact, no bump. The rear glass was replaced 18months ago by Austral because of a problem with the high mounted brake light. My question is 2 fold; has anyone else encountered this problem and what might have caused the issue. I am now out of warranty so am up for about $650 to replace but i want to make sure it doesn't happen again. Thanks in advance for the illumination.

[slug_burner]

Have you got a big tyres? Have you got your spare hanging off the door? A bit of a long shot but the door frames used to crack due to the weight of the tyre hanging on the door. If the frame has moved it could crack the glass. Spare wheel carriers helped to reduce the incidence of cracking door frames. I am not sure but I think that LR may have strengthened the back door and you traveling on bitumen makes it more of a long shot.

[flagg]

Check with your insurance provider, mine does excess free glass replacement.

[isuzurover]

Towing a trailer?

Work vehicles used outback towing box/camper trailers used to constantly smash rear windscreens - rock bounces off trailer and ricochets into winscreen.

[superquag]

... had a rock take out a tail-light, same cause...:(

$650 for a rear windscreen ? ouch... what's it made of, - bullet-proof optical glass???

[alittlebitconcerned]

What a strange coincidence. I awoke to find the rear windscreen on my 07 Puma shattered one morning last December. Although shattered it held it's shape and you could see the radiating lines of multiple cracks originating from the break light near the top of the windscreen. There were no impact marks or chips from the glass, just a windscreen in a thousand pieces but still holding together. I've still got no idea what caused it as it wasn't like that when I left it the night before.

[miller.rhys]

On a previous car I owned not land rover I had a rear window break overnight for no apparent reason. When it was removed the only thing I could find was a small amount of rust in the bottom frame. It seems this small deflection in the glass was enough to crack it.


I also recently took out a shower screen. Unfortunately in our area you cannot recycle plate glass in the bins and on ringing the recycle centre they told be to break it up and put it in the bin. Turns out the glass was tempered like in some car windows and despite using in a hammer I was unable to break it hitting the flat surface. I recalled hearing tempered glass was very fragile if hit on the end. With only the slightest tap of the hammer on the end the piece shattered into 1000's of pieces.


It doesn't seem to take much of the glass is hit or stressed in just the right spot to make it shatter.

[Defender Mike]

My father in law had the same with a ford / Mazda ute years ago. His broke when the tight fitting glass expanded on a hot day. Glass is funny stuff no 2 pieces break the same way some say its a liquid with surface tension holding it all together.

[Blknight.aus]

it is, go have a look at a really old house with orignal glass and you can see it welling at the bottom and stretching at the top...

a very slight bending effort on a straight piece of glass with a good thermal shock is enough to do it as is a pressure change (say by opening a window while at sped or having the wind gust from a head wind to a side wind blowing into the open window and trying to inflate the car)

but you try to break a piece of glass when its an emergency
epic fight scene top secret!.avi - YouTube

[skidrov]

OK, interesting... My MY10 110 had its rear windscreen (i.e. the rear door glass) suddenly break for no apparent reason too... I did not see it happen, and I must admit that it was left in a suburban carpark when it occurred (where, I agree, anything can go down) but it wasn't the world's wildest area (Malvern, VIC, just off Glenferrie Rd.). It also wasn't the world's hottest day by any stretch (about 2 months ago, well away from Melbourne's recent heatwave). The break seemed to be radiating from the high-mounted stop light but not entirely sure - hard to tell.

Insurance company covered it for "free" with the touted prices being similar to those quoted by other posters, glass installed looks to be genuine, with Land Rover/Pilkington branding.

It's been nagging at my tiny mind, what might have occurred; we don't exactly have a full outbreak here, but it's interesting that it's not just one of us...

[Goenin]

The last week here in Melbourne was 40 every day.
I know of 3 vehicles that blew screens/glass after the weather cooled.
One was on the news. The new Hyundai with the glass roof. Blew and injured the people in the car.
My mate corvette window went the same way in the 90's.
Only toughie glass though.
Could this be your case also?

[Reads90]

... had a rock take out a tail-light, same cause...:(

$650 for a rear windscreen ? ouch... what's it made of, - bullet-proof optical glass???

That is what I thought. It's is not like it is curved or anything.

[towe0609]

I had one half of the rear sliding window on my 130 dual cab break while the car was parked up overnight. I don't really recall the weather at the time.

I drilled the frame out, took it to my local glazier, who cut and fitted a single pane of 'windscreen' glass for about $50. Riveted the frame back in and no probs since.

[Chops]

... had a rock take out a tail-light, same cause...:(

$650 for a rear windscreen ? ouch... what's it made of, - bullet-proof optical glass???

On a trip up to QLD years ago, I broke both Barn door windows in the Toyo, they wanted well over $1000 to replace both, ended up buying two complete doors for $200.

[spudboy]

... some say its a liquid with surface tension holding it all together.

Off topic, but....

According to Dr Karl, this is an urban myth. Old glass that is thicker at the bottom was just installed that way, in the days when it was very difficult to get a perfectly flat piece of glass.

[Blknight.aus]

I've seen that and I fully undersand all of the science behind why its not so but I always wondered why when you look at some of the really old glass its got "stretch marks" that come away from the top framing where its been clamped and why some panes have been found with a pronounced "ridge" where it was clamped at the bottom. I know about the differences in thicknesses from when plate manufactuing was done by spinnign a bubble to make it flat (its actually really cool to watch if you ever get to go see a glass blowing works show)

I've heard claims of "its erosion, its staining from the wood and paint they used"

Erosion I could buy if it was only on the exposed side

the staining, might fit but Id expect it to be more uniform....

of course it could also be a multitude of factors,

heat from house fires softening the glass which was made from lower grade materials that contained imperfections along with uneven weight distribution within the glass that promoted the glass "wanting" to relax and reform its shape slightly....

I know the science is right, but it just feels wrong.


True the following vid isnt on the exact same subject

Mystery of Prince Rupert's Drop at 130,000 fps - Smarter Every Day 86 - YouTube
but my thinking is
what if

"the same principle applies, the glass was made and had this effect going on but as the glass is thermal cycled over centuries it flexes itself back to a more natural position"

[uninformed]

That is what I thought. It's is not like it is curved or anything.

Cost of Glass + they usually allow a new seal + labour + pofit.

BTW a genuine LR seal for the front windscreen is $200+

[SnowTurtle]

Just had my experience of rear window shattering today. Didn't see the thread before posting mine
http://www.aulro.com/afvb/showthread.php?p=2079297#post2079297

All sounds the same though, '09 110 wagon, seems to have initiated in the centre just below the brake light mount

[shining]

I had the rear window go in the D1 in about 1998. It was a very frosty night and the vehicle was parked outside. In the morning....crazed (shatterproof glass). I think I found a tiny chip from a stone probably while towing although I hadn't been towing anything for some weeks towing and the temperature change probably precipitated the failure.

[POD]

There seems to be a common theme in that the glass breakage radiates from the brake light area; are these central brake lights factory-fitted, or installed later for the Aus market? Any stress put on the edge of the glass can result in later failure.

[alien]

I've also just had the rear door glass replaced on our 110.
Background....
We have just done 2 weeks tripping around Melrose/Cobber Pedy/Lake Ayer/Flinders so air temperatures 15->early 30's.
In the Flinders we saw a few drop of rain before the group dispersed.
After a cool day we stoped beside the Murray at Swan Reach for the night.
It rained a fair part of the night.
On getting up I opened the door and all was good.
5 minutes latter after returning from the kidney empting exercise the glass was shattered.
The brake light was hanging down and my thought was either a branch feel on it(unlikely as no evidence) or the temperature change in the glass.
I'm also wondering if there is more to it now.


Fortunately I have tint fitted so it held together, a little tape and I put a tarp around the door to do 80Km for the repair.
For us it was included in our insurance including the re-tint.

[alien]

There seems to be a common theme in that the glass breakage radiates from the brake light area; are these central brake lights factory-fitted, or installed later for the Aus market? Any stress put on the edge of the glass can result in later failure.
The high mount light is factory fitted.
They are bolted to 2 points the are attached to the glass.
The power contacts are also attached to the glass in the same area and have circuits to the lower edge along with the demister wires.

[AndyG]

It's almost. Like the high light is expanding / shrinking at a different rate to the main glass and creating fatigue at the mounting points :confused:

[tact]

but my thinking is what if
"the same principle applies, the glass was made and had this effect going on but as the glass is thermal cycled over centuries it flexes itself back to a more natural position"

I think you'd be very close with this thinking. Just in the last month something came across my desk - science re-looking at this. Apparently the (new) thought is that glass is a solid. It's just one of those solids that takes a huge amount of time to take on typical solids crystalline form after cooling.

Apparently metals and stone etc all form their crystalline ordered structure as the cool or shortly thereafter. We can sometimes change the internal structures with tempering techniques. Glass does the same - but slowly over hundreds of years... So the thinking goes.

Google for a more intelligent or articulate explanation. My memory of what I read recently is not going to be perfect.

[jimr1]

Some years ago I had a Peugeot van , I was driving It , looked in rear mirror , as the glass in the tail gate went a bit cloudy . There's me thinking what the hell going on ? It got worse as I watched It . We're talking just a few seconds . Then It went bang !! What I'd done was left the heated screen switched on , The switch and light were down low , so weren't easy to see , I was lucky because It was covered by my insurance , I did say a stone or rock must of hit It . With the Land Rover rear doors , up until the Puma they were held in with alloy strips and screws , they can and do stand up to lots of abuse . The Puma are held in with rubber , they should be even better when It comes to vibration ! There should be no glass /metal contact , so I wonder if It's electrical overheating , or even a short ? One thing for sure is they shouldn't just break for no reason !!.. Jim..

[skidrov]

Resurrecting this given a recent observation. Bear with me...


I recently had pointed out to me by my servicing dealer that my high-mount brake light wasn't working, and that they couldn't fix it without replacing the door glass. We put it in the "leave for next time" category, and today I had a look at what was going on.

It looks to me like gunk can get trapped between the large/thick/tapered rubber "gasket" that's between the brake light housing & the glass, and that over time this gets wet, conducts, and causes arcing between the door frame and the positive metal track on the glass - the track for the brake light (there's two tracks - one for demister, one for the brake light). On my car, this had cause pitting in the big gasket and had also burned away the track itself, so that there wasn't a circuit for the brake light. But, it didn't blow a fuse at any stage.

Now, the reason I've posted under this thread is that I DID have the rear door glass replaced around 2 years ago, and so all this happened in a fairly short time. I ALSO noticed that there is pitting in the glass itself - the NEW glass.

So, I then begin to wonder if the glass breakages that seem fairly common are related to this - arcing and pitting occurs, plus spot heating I presume, and then the firm ride/rough surface combo that these vehicles are often subject to does the rest.

I'd be interested to hear if others check their brake light and find pitting in either the big gasket or the glass, or a burnt track.

Finally, rather than replace the glass and repeat the cycle, I ran some two-strand wire up to the brake light, wired it to the appropriate leads and so I'm now powering it independent of the glass track - I don't want to replace the glass just for this reason!