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#2
09-23-2006, 05:34 PM
RE: PANARAMIC ROOF EXPLOSION
Yikes! Having your sunroof explode has got to be a seriously freaky event. That would scare the bejezus out of me; I'm glad to read no one was hurt.
Did some google surfing, and have come across reports of other panoramic sunroofs exploding, although not in another MB (I found Citroen (sp?), Mini and BMW tales). Doesn't mean other MB incidents aren't out there, but it doesn't seem common as rain either. I also learned that the windscreen is typically the only laminated safety glass in the car (two glass layers surrounding a clear plastic layer). When saftey glass has a problem, it may crack but usually doesn't exploded, and often hangs together when shattered in a sheet. The other glass pieces are usually tempered, which makes them stronger, but can have sudden and catastrophic failure when a weak point decides to give. Even it is designed to fracture into smaller, safer pieces, instead of breaking into larger, potentially leathal shards. Having once experienced the small pieces from a vehicle break-in, the safer sizing comes at a cost of having glass go literally everwhere inside the vehicle. Neither is fun, but maybe the smaller pieces are a bit better than the alternative. Your concern about the possiblity of harm from these small shards seems well founded, and it makes me wonder why *all* glass in vehicles is not required to be the laminated type. I suspect it's yet another instance where the cost was in some fashion judged not worth it.
To MB's credit, it is *possible* that a rock-chip in the sunroof went un-noticed until it weakened to the point of failure. To their non-credit, a sunroof panel should never be placed under the type of stress where such a small nick could lead to an exploding sheet of glass. As sunroofs are designed to slide back and forth, and pop up, they are not part of the structural rigidity of the roof, but should instead rest inside of a rigid hole. Now a large plate of glass, held horizontally and subjected to bouncing, might experience some flex that could lead to failure. But sunroofs, particularly large ones, should be designed to be well beyond the safety margin for that type of failure, even with a small crack.
If you knowingly drove down a bumpy road with a glaring crack in the roof, then shame on you. If, as it sound like, you had no visible damage to your roof and went from fine to kaboom, *and* it was indeed a failure from a prior minor ding, then shame on them. Glass panels in vehicles should have benign failure modes from hazards present in everyday life. Finally, if you drove down the road and experienced a freak impact, then count yourself lucky. There are about 6 people each year in my state (Colorado) who die from falling rocks, and if you had a near miss then be glad it wasn't your time.
In fact, it looks as if the key to whether you should feel outraged or not is to verify that the upward bulging nature of the hole indicates something other than an instananeous impact failure (from a rock, brick, meteorite etc.). If I recall correctly, small projectiles (bullets, BBs, pellets etc) typically have an "exit wound" larger than the entry wound, and you can tell the direction of impact from that. I'm not sure the same applies to larger items. Things like golf *****, bricks, stones etc often travel at lower speeds and impact a larger surface area; many of them get bounced or thrown back upon impact. My experience with windshield hits has generally been instances where the hole doesn't go through, and gets smaller as it gets deeper (crater like). It's possible that your sunroof was impacted by something sizeable and relatively slow, and that the glass bowed, rebounded and the weakend glass gave way. Again, you'd need to find a knowledgeable source on impact physics to know for sure that your symptoms are *only* explainable by a defect, and not by an impact of some sort.
Your post certainly has made me rethink the desirability of panoramic sunroofs in general, and has resolved me to fix a ding in my passenger window that I've been ignoring. (Heard a noise like someone shooting my car, and later found a 1/8 wide gouge out of the passenger window just above the door lock. How any rock could get enough lateral velocity to hit that hard mystifys me, but I've the evidence to prove it happens.)
Best of luck getting your situation resolved. If you end up concluding that it was a freak incident, that is unlikely to happen to the same person twice, I doubt anyone would argue against you. If you end up convinced that it's a vehicle design defect, then for sure move on from this vehicle and others with large sunroofs. I would not be surprised to see future saftey regulations on the design and implementation of panoramic sunroofs across all vehicle makes; there are certainly a number of frightening reports out there similiar to your own. Thanks for sharing your tale; you never know when a little information can make a difference and same someone else out there some greif.
Did some google surfing, and have come across reports of other panoramic sunroofs exploding, although not in another MB (I found Citroen (sp?), Mini and BMW tales). Doesn't mean other MB incidents aren't out there, but it doesn't seem common as rain either. I also learned that the windscreen is typically the only laminated safety glass in the car (two glass layers surrounding a clear plastic layer). When saftey glass has a problem, it may crack but usually doesn't exploded, and often hangs together when shattered in a sheet. The other glass pieces are usually tempered, which makes them stronger, but can have sudden and catastrophic failure when a weak point decides to give. Even it is designed to fracture into smaller, safer pieces, instead of breaking into larger, potentially leathal shards. Having once experienced the small pieces from a vehicle break-in, the safer sizing comes at a cost of having glass go literally everwhere inside the vehicle. Neither is fun, but maybe the smaller pieces are a bit better than the alternative. Your concern about the possiblity of harm from these small shards seems well founded, and it makes me wonder why *all* glass in vehicles is not required to be the laminated type. I suspect it's yet another instance where the cost was in some fashion judged not worth it.
To MB's credit, it is *possible* that a rock-chip in the sunroof went un-noticed until it weakened to the point of failure. To their non-credit, a sunroof panel should never be placed under the type of stress where such a small nick could lead to an exploding sheet of glass. As sunroofs are designed to slide back and forth, and pop up, they are not part of the structural rigidity of the roof, but should instead rest inside of a rigid hole. Now a large plate of glass, held horizontally and subjected to bouncing, might experience some flex that could lead to failure. But sunroofs, particularly large ones, should be designed to be well beyond the safety margin for that type of failure, even with a small crack.
If you knowingly drove down a bumpy road with a glaring crack in the roof, then shame on you. If, as it sound like, you had no visible damage to your roof and went from fine to kaboom, *and* it was indeed a failure from a prior minor ding, then shame on them. Glass panels in vehicles should have benign failure modes from hazards present in everyday life. Finally, if you drove down the road and experienced a freak impact, then count yourself lucky. There are about 6 people each year in my state (Colorado) who die from falling rocks, and if you had a near miss then be glad it wasn't your time.
In fact, it looks as if the key to whether you should feel outraged or not is to verify that the upward bulging nature of the hole indicates something other than an instananeous impact failure (from a rock, brick, meteorite etc.). If I recall correctly, small projectiles (bullets, BBs, pellets etc) typically have an "exit wound" larger than the entry wound, and you can tell the direction of impact from that. I'm not sure the same applies to larger items. Things like golf *****, bricks, stones etc often travel at lower speeds and impact a larger surface area; many of them get bounced or thrown back upon impact. My experience with windshield hits has generally been instances where the hole doesn't go through, and gets smaller as it gets deeper (crater like). It's possible that your sunroof was impacted by something sizeable and relatively slow, and that the glass bowed, rebounded and the weakend glass gave way. Again, you'd need to find a knowledgeable source on impact physics to know for sure that your symptoms are *only* explainable by a defect, and not by an impact of some sort.
Your post certainly has made me rethink the desirability of panoramic sunroofs in general, and has resolved me to fix a ding in my passenger window that I've been ignoring. (Heard a noise like someone shooting my car, and later found a 1/8 wide gouge out of the passenger window just above the door lock. How any rock could get enough lateral velocity to hit that hard mystifys me, but I've the evidence to prove it happens.)
Best of luck getting your situation resolved. If you end up concluding that it was a freak incident, that is unlikely to happen to the same person twice, I doubt anyone would argue against you. If you end up convinced that it's a vehicle design defect, then for sure move on from this vehicle and others with large sunroofs. I would not be surprised to see future saftey regulations on the design and implementation of panoramic sunroofs across all vehicle makes; there are certainly a number of frightening reports out there similiar to your own. Thanks for sharing your tale; you never know when a little information can make a difference and same someone else out there some greif.
#3
09-23-2006, 09:29 PM
RE: PANARAMIC ROOF EXPLOSION
Just to clarify...the glass exploded outwards with the glass buldging outwards rather than something hitting the glass from the outside which would cause the glass to cave inwards. My friends C230 coupe had the same problem and the dealer warrantied the glass without any questions. The dealers explanation at the time was that the glass wasn't heat treated properly or that it was mis-aligned during installation.
#4
09-24-2006, 05:15 AM
RE: PANARAMIC ROOF EXPLOSION
Hi,
An unfortunate but not totally unheard of issue.
Safety glass comes in two types. Tempered and Laminated. Both have advantages and disadvantages and usage is usually determined by application NOT cost alone.
For instance most windscreen glass in the early days used to be laminated. (used to go yellow). However the introduction of curved glass for styling reasons challenged the manufacturers of laminated glass and tempered glass started being used instead. Since temperted glass is a single layer it overcame the glass/plastic/glass bonding problem which had been exaccerbated by the introduction of curves AND also happened to be cheaper. However customers became concerned regarding the mode of failure due to the loud bang and glass debris plus of course the inconvenience of having no screen in inclement weather etc to continue their journey.
As a consequence manufacturers perfected the laminated bonding process and luxury cars (now all cars) started moving back towards laminated.
Tempered glass continued to be used for side and read windows since laminated is potentially dangerous for side windows in side impact, roll overs etc where the large pointed shards of glass (partially held in place by the interlayer) can cause severe damage to occupants.
INTERESTINGLY some manufacturers (including MB and BMW) are beginning to move to laminated side windows for security reasons. to address external noise levels and Auto theft in the UK (and I guess other locations) since tempered glass can be broken in a fraction of a second with an auto centre "pop" in order to steal the car, or contents.
Safety concerns are addressed by the use of side air cushions etc.
It is also interesting to note the MB have a problem with delam on the side windows due to water ingress. see other post topics.
Now tempered glass is STRESSED glass. It is designed to break into thousand of safe (at least relativel to laminated) pieces.
During the manufacturing process cold air is blown onto the hot glass which causes internal stresses (you can see these visually sometimes in the sun). The slightest nick and the stresses get concentrated and the glass EXPLODES into thousand of SAFE (relatively) fragments.
Driving behind laminated glass without airbag AND safety belts is NOT a sensible thing to do. BE WARNED!!
I don't think you should be too hard on MB for the failure. Glass is not made by MB and the big suppliers make millions of pieces a year with minimal faults for all auto manufacturers worldwide. MB OE glass actually has a STAR on it but it is still made by Triplex. SIV etc.
However tempered glass failure is distressing/frigtening due to the explosive nature of the failue and maybe MB should have been a little more understanding ESPECIALLY if the car is relatively new i.e. less than 3 years. If the car is older then something MUST have initiated the failure. it can't be the car itself because it has already survived three years etc.
Have you considered claiming against your auto glass cover?
Although you suspect the failure was from the inside out I do not think that this is the case. I suspect that it will have been a low flying object (stone) from another car, kids on a bridge etc.
The reason for the inside out failure is that the pressure in the car is somewhat higher than outside at speed. This small pressure difference, even with the back of the roof ajar, acts against a large surface area. At failure the "whoosh" of air (like in an aircraft window failure) is from inside to outside hence the bulging remant pieces.
I would suggest you have just been unlucky and such an unlikely event should be covered by your insurance.
MB have a lot to answer to but I think that this one is not down to them.
Hope this helps keep you onboard with MB.....NB I have nothing to do with MB other than the fact Irun a couple of MB cars myself.
Stuart.
An unfortunate but not totally unheard of issue.
Safety glass comes in two types. Tempered and Laminated. Both have advantages and disadvantages and usage is usually determined by application NOT cost alone.
For instance most windscreen glass in the early days used to be laminated. (used to go yellow). However the introduction of curved glass for styling reasons challenged the manufacturers of laminated glass and tempered glass started being used instead. Since temperted glass is a single layer it overcame the glass/plastic/glass bonding problem which had been exaccerbated by the introduction of curves AND also happened to be cheaper. However customers became concerned regarding the mode of failure due to the loud bang and glass debris plus of course the inconvenience of having no screen in inclement weather etc to continue their journey.
As a consequence manufacturers perfected the laminated bonding process and luxury cars (now all cars) started moving back towards laminated.
Tempered glass continued to be used for side and read windows since laminated is potentially dangerous for side windows in side impact, roll overs etc where the large pointed shards of glass (partially held in place by the interlayer) can cause severe damage to occupants.
INTERESTINGLY some manufacturers (including MB and BMW) are beginning to move to laminated side windows for security reasons. to address external noise levels and Auto theft in the UK (and I guess other locations) since tempered glass can be broken in a fraction of a second with an auto centre "pop" in order to steal the car, or contents.
Safety concerns are addressed by the use of side air cushions etc.
It is also interesting to note the MB have a problem with delam on the side windows due to water ingress. see other post topics.
Now tempered glass is STRESSED glass. It is designed to break into thousand of safe (at least relativel to laminated) pieces.
During the manufacturing process cold air is blown onto the hot glass which causes internal stresses (you can see these visually sometimes in the sun). The slightest nick and the stresses get concentrated and the glass EXPLODES into thousand of SAFE (relatively) fragments.
Driving behind laminated glass without airbag AND safety belts is NOT a sensible thing to do. BE WARNED!!
I don't think you should be too hard on MB for the failure. Glass is not made by MB and the big suppliers make millions of pieces a year with minimal faults for all auto manufacturers worldwide. MB OE glass actually has a STAR on it but it is still made by Triplex. SIV etc.
However tempered glass failure is distressing/frigtening due to the explosive nature of the failue and maybe MB should have been a little more understanding ESPECIALLY if the car is relatively new i.e. less than 3 years. If the car is older then something MUST have initiated the failure. it can't be the car itself because it has already survived three years etc.
Have you considered claiming against your auto glass cover?
Although you suspect the failure was from the inside out I do not think that this is the case. I suspect that it will have been a low flying object (stone) from another car, kids on a bridge etc.
The reason for the inside out failure is that the pressure in the car is somewhat higher than outside at speed. This small pressure difference, even with the back of the roof ajar, acts against a large surface area. At failure the "whoosh" of air (like in an aircraft window failure) is from inside to outside hence the bulging remant pieces.
I would suggest you have just been unlucky and such an unlikely event should be covered by your insurance.
MB have a lot to answer to but I think that this one is not down to them.
Hope this helps keep you onboard with MB.....NB I have nothing to do with MB other than the fact Irun a couple of MB cars myself.
Stuart.
