Mystery shattering rear glass

**alien** · 19th April 2015, 10:09 AM

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** · 19th April 2015, 10:16 AM

Originally Posted by 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.

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** · 19th April 2015, 12:27 PM

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

**tact** · 19th April 2015, 12:53 PM

Originally Posted by Blknight.aus

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** · 22nd April 2015, 01:48 AM

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** · 9th July 2016, 05:24 PM

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!

Thread: Mystery shattering rear glass

Thread Tools

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions