View Full Version : Rollcage issues
At the risk of appearing opportunistic...
This is a link to a post about the 10.5 Mustang whose rollcage weld had no penetration.
http://www.bangshift.com/blog/Insane-Carnage-Photos-A-10.5-Tire-Mustang-Meets-Its-Maker.html (http://www.bangshift.com/blog/Insane-Carnage-Photos-A-10.5-Tire-Mustang-Meets-Its-Maker.html)
I would never say that the TigerCage would protect a driver completely from such a violent crash, but one has to think about the concept of “bending before breaking”, “crash energy absorption”, and the structural integrity of a bolted connection versus a weld that may be [unknowingly] inferior.
In a related incident last week, I was approached by a Porsche owner who wanted to develop a cage for a particular Porsche racing series. He brought his club racer spec car down for us to look at as a starting point. This was a true race car built by an experienced shop. The very first thing I saw when I poked my head in the window was that the connection between the main hoop and the rear brace was only welded about halfway around, apparantly because it was hard to get to. I've seen this kind of thing before and just can't help but think there is a better way.
If I get really aggressive in promoting this product maybe I need to collect a library of these kinds of incidents. I hesitate to do that because it preys on others misfortunes…never a good business path, at least not in my book. On the other hand, if we could initiate racers thinking about the integrity of their welds instead of just taking it for granted, we could make these cars safer, be it with a welded cage or a TigerCage. At the very end of the day it is truly about protecting lives.
It should certainly cause all of us to think just a little.
rogue
10-19-2010, 11:17 AM
Get it certified yet?
DynoDon
10-19-2010, 11:51 AM
Obviously that was a very violent wreck. The biggest thing that bothers me is the statement "To Our Untrained Eye ..." Well, that is just opening a whole can of worms isn't it. If you do not have expertise in these types of things, keep your mouth shut.
I am a former licensed SCCA Technical Inspector, and I regularly stopped cars from racing that had cages that were only partially welded per Brett's explanation of the customer car. I would NEVER pass a car through tech that way. It is one of the reasons that my shop sold Safety Devices brand cages for folks that did not have the proper welding skills and didn't want to spend the money to have us build a legal custom built cage. They are used extensively in Europe and are a very well engineered and thought out bolt together system. Done right a bolt together can be very effective.
LateNight72
10-19-2010, 12:30 PM
Poor weld penetration and seams that aren't fully welded are definitely the number one issue with cages.
However, a couple clamps rated at 450lbs (IIRC) of holding force and 250lbs at the pivot, aren't going to do much either in a wreck like that, they'd probably do less IMHO.
James OLC
10-19-2010, 01:05 PM
Obviously that was a very violent wreck. The biggest thing that bothers me is the statement "To Our Untrained Eye ..." Well, that is just opening a whole can of worms isn't it. If you do not have expertise in these types of things, keep your mouth shut.
That statement - "To our untrained eye" - was made by the Bangshift reporter who is... with respect to rollcage fabrication... admittedly untrained. He is reporting on a story so I don't think that there should be an expectation of expertise. And, in his defense, my daughter could probably look at that weld and see that there is no significant penetration. I don't see any can of worms there and I don't see why he should "keep his mouth shut".
carguy502
10-19-2010, 01:25 PM
That is a violent wreck for sure and I'm glad he walked away from it. One thing that does catch my attention was some of the bangshift members were saying it is common for chrome-moly to break like that. Though it is obvious that the weld lacked penetration, is this true of chrome-moly? If so, why manufacture a cage out of it if its purpose is to protect the driver? Was this just a couple of internet racers spouting off?
dropit69
10-19-2010, 01:52 PM
Wow that could have been real bad..thats problem i have buying a car already caged..if i dont see it built i dont trust it..i think i want a Nascar chassis guy to build my cage ..watch them wreck..
Bryce
10-19-2010, 02:45 PM
Bret, have you been able to do any destructive testing on your cages? I mean take a junker with a solid structure and put your cage in it and roll it at speed.
Bret, have you been able to do any destructive testing on your cages? I mean take a junker with a solid structure and put your cage in it and roll it at speed.
This is a very valid and seemingly simple question.
I will freely admit that I have not crashed a car with our cage in it. I am a lot of things but stop short of being a crash test dummy:) What we have done is a fair amount of strength evaluation of materials, fasteners, and structural design. Having said that I would agree that an actual crash, or better yet, a series of crashes to simulate the many variations that such an event could occur, would be a "better" testamonial to the effectiveness of the TigerCage. It would also be a better testament to each and every welded cage out there as well, but that would be another whole level of unfeasible.
I would like to make something really clear: We do not guarantee the survivability of any crash. To do so would be a completely false statement and would offer a sense of safety that simply can't exist in a high speed driving environment. We can only offer that the TigerCage will offer you more protection than no cage at all. We are basing this statement on our studies of materials, fasteners, and structural design. The only way to absolutely ensure the survivability of any dynamic driving action is to not hit anything solid in a way that was not intended. [Don't crash]
Don't misinterpret this as a defensive statement...it is only meant to remind everyone that high speed driving events [otherwise known as racing] can be dangerous if and when the unexpected happens. The goal is to prepare yourself using the most education and common sense possible.
To answer the certification question:
YES. ECTA [East Coast Timing Association runs the Maxton event] has certified the TigerCage for competition up to 175mph. This just happened a couple of weeks ago.
MrQuick
10-19-2010, 07:17 PM
the driver did walk away so to a point the cage did do its job. The amount of force in that particlar area was greater than what I would expect a cage to survive. What I am trying to say is break away would have happened reguardless. If not there maybe at the floor or lower main hoop pull.
Full surround plate gussets would have been ideal in those higher corners.
https://static1.pt-content.com/images/pt/2010/10/IMG_0138-1.jpg
I'd hate/cringe to speculate what would have happened without a cage.
overZealous1
10-19-2010, 08:01 PM
i agree, maybe not a certified aircraft weld, but probably would have held up in a lighter roll over. THAT is not a light rollover or anything of the like. one guy said not annealed, and i tend to agree abit. could have put too much heat in the weld weakening the tubing right after it. the weld is left on the halo, but tore at the down tube.
wedgehead
10-20-2010, 07:50 AM
I know the guy that built this car. talked to him about the crash yesterday. The tube broke off at the weld after the car barrel rolled 5 times and end over end 6 times, came to rest on roof. I think the cage held up very good for amount of energy that was involved in the crash.. More pics at DFWstangs.com. Look under pumpkinhead.
moreHP
10-20-2010, 09:42 AM
If the owner of the car walked away and is still around to tell the story then I have to say he is a lucky man! I have seen crashes that didnt tear up the car this bad where there was injuries.
One thing I can add and would like people to check on their own cars is the seatbelt mounts. Make sure they are reinforced and cant pull out in a hard crash. This gets overlooked all too often and just because the belts are current on their cert doesnt mean they are actually mounted as good as they should. I only mention this because a good friend of mine was hurt in a crash when the lap belt pulled out of its mount on the drivers side making the 5 point useless and he got banged up pretty bad as a result. The same thing can happen on the welds for the mounts.
Bryce
10-20-2010, 12:03 PM
I know the guy that built this car. talked to him about the crash yesterday. The tube broke off at the weld after the car barrel rolled 5 times and end over end 6 times, came to rest on roof. I think the cage held up very good for amount of energy that was involved in the crash.. More pics at DFWstangs.com. Look under pumpkinhead.
But you never want the weld to break. The weld should be the strongest part if you have good penetration with the correct filler rod material. I am glad the guy survived. So the cage worked. But could have been better.
John Wright
10-20-2010, 12:11 PM
Weld failure analysis is complicated.....it would be hard to tell from just looking at those pics and come up with a determination of why that joint in question failed. Too many variables and unknowns. I'm just glad to hear that the driver is still with us and survived that violent crash.
When I say that it is complicated, I understand some of what goes on in these investigations.....I have close friends who do weld failure analysis for insurance companies, they use alot of high priced toys to come up with proof positive conclusions as to why something failed.....starting with an electron microscope.
sevillaz28
10-20-2010, 04:16 PM
Looking at the halo bar in the pic I think the cage and its welds did a great job. If there were any bad welds thank god it wasen't in the halo bar. Seeing how bent it is, a bad weld could have snapped and killed the driver. Looking at accidents like this make me feel good about the people that put a cages in properly and save the lives of us Car Nuts.
Bill Howell
10-20-2010, 04:47 PM
First, this was one hell of a crash and I am not sure at what point is enough enough. At what point is good enough, good enough? Obviously you can overload any rollbar or weld.
That said, to answer your question Bret, I don't think you can build anything too safe or make people aware of possible faulty equipment. Look what happened in NASCAR after Dale E. Sr. was killed almost 10 years ago now. The one thing that came out of that tragedy was more safety. So, to show past failures and explain them IMO is a good thing.
MrQuick
10-20-2010, 07:59 PM
Right, how much is enough and failure is only measured by failure. nice point Bill.
This is a great conversation...people are THINKING about how to make their cars safer.
The point that this cage did its job by saving the driver is well taken.
LeighP
10-24-2010, 01:07 AM
One thing I noticed when looking at video of the Tiger Cage is that the main hoop is right behind the head area of driver and passenger......I'd be a little concerned about head injuries in a street accident when no one is wearing helmets. Is there some structual reason the hoop is not a bit further back?
Just asking...not taking a shot at your system.
Bryce
10-24-2010, 06:38 AM
NHRA rules are 2" over the drivers head and no more than 6" behind.
mike w.
10-24-2010, 07:56 AM
but nhra insist on wearing a helmet! i have been in a caged car on the road where the driving got a little "spirited" and a little sideways and yes it hurts like hell, i dont think i would ever put a cage in a streetcar again as you would look stupid wearing a helmet driving on the street and a light side hit would do you way more damage hitting your head on the item that is supposed to be protecting you! i wonder how many years it will be before someone comes up with a fit friendly airbag system? for our older rides, after seeing that 59 impala getting wasted by the 09 malibu on the insurance test it would help some,
Tig Man
10-24-2010, 08:10 AM
Most roll cage designers would cringe if they saw the chassis on a shaker rig!! Total built race cars are scarey. I think your kidding yourself welding plates to a stamped sheet metal rocker box and think your gonna be safe in a crash! A total lack of cross bracing and triangulation along with poor welding is a lot to consider when this happens. It's always a matter of time! Whats your life worth? A cheap cage to get you past the tech guy?
Mark
One thing I noticed when looking at video of the Tiger Cage is that the main hoop is right behind the head area of driver and passenger......I'd be a little concerned about head injuries in a street accident when no one is wearing helmets. Is there some structual reason the hoop is not a bit further back?
Just asking...not taking a shot at your system.
This is an area that is tough to address short of building a custom fitted rollcage. In general, we place the main hoop in line with the leading edge of the B pillar. This seems to work well with both the car and the largest percentage of drivers out there.
DynoDon
10-26-2010, 01:32 PM
That statement - "To our untrained eye" - was made by the Bangshift reporter who is... with respect to rollcage fabrication... admittedly untrained. He is reporting on a story so I don't think that there should be an expectation of expertise. And, in his defense, my daughter could probably look at that weld and see that there is no significant penetration. I don't see any can of worms there and I don't see why he should "keep his mouth shut".
This was not a simple roll over. By most accounts, this car rolled 5 or 6 times and then went end over end 5 more times, ending up on the roof. Had there been no penetration of the weld, this junction would have failed very early in the crash and the Halo bar and that leg would have been crushed much further down. It did eventually fail, and it appears that the penetration was not as complete as it could/should have been but all in all it held up very well. To make an off the cuff statement with no expertise and no analysis of the failure which could condemn the builder, is irresponsible and in my opinion inappropriate. When you look at the entire car you can tell that this was very violent and was not an average roll over where a failure like that would be completely unexpected, but I think in this case a more thorough expert analysis is in order before making uneducated statements as to cause of failure. JMO
TitoJones
10-26-2010, 02:22 PM
This was not a simple roll over. By most accounts, this car rolled 5 or 6 times and then went end over end 5 more times, ending up on the roof. Had there been no penetration of the weld, this junction would have failed very early in the crash and the Halo bar and that leg would have been crushed much further down. It did eventually fail, and it appears that the penetration was not as complete as it could/should have been but all in all it held up very well. To make an off the cuff statement with no expertise and no analysis of the failure which could condemn the builder, is irresponsible and in my opinion inappropriate. When you look at the entire car you can tell that this was very violent and was not an average roll over where a failure like that would be completely unexpected, but I think in this case a more thorough expert analysis is in order before making uneducated statements as to cause of failure. JMO
It did not hold up very well at all. The tube broke.
If you want to see what a properly welded cage does in a 100mph accident, look here:
http://corner-carvers.com/forums/showpost.php?p=836523&postcount=853
That car hit a wall at 80-100mph and the guy walked away from it with no injury. The cage deformed, factory spot welds split open, but at no point did any tube break off at the welded seam. The builder should thank his lucky stars that the driver was not killed, but to praise him for that work? Not a chance in hell.
Tyler
MrQuick
10-26-2010, 06:51 PM
but that was an over and over again impact Ty, and without data on at which point the bar broke would determine its failure point due to improper fab or metal fatigue. If it broke at first impact then I see it but if it had infact broke at the 10th point of impact then I can understand.
Looking at the multiple impact points its hard to believe someone survived.
https://static1.pt-content.com/images/pt/2010/10/IMG_0138-1.jpg
The roll cage did its job in the CC thread when it hit the tire wall and look at the point of impact, that is why that 3 point corner is where it is. A well planned cage. What a shame, all that over a $12 brake line failure. Bravo for the driver in not taking anyone with him. Watching the video he was 9 feet from getting by but going into traffic.
John Wright
10-27-2010, 03:21 AM
I think in this case a more thorough expert analysis is in order before making uneducated statements as to cause of failure. JMO
Did anyone put a fillet weld gage on those jonts to determine if the welder used enough filler when tig'ing the joint up? Did anyone determine if the fillet weld size was engineered or did someone use a rule of thumb to size the welds? Did anyone use an electron microscope to see if the heat affected zone was too large or too small indicating that the welding procedure may have been at fault(heat input joules per in = amps x volts x 60 /travel speed measured in in/min). Did the fracture surface get examined by that same microscope to see if there are any indications that the material failed due to fatigue over a period of time or from multiple impacts during the wreck, or maybe if it just sheared in one quick impact? Could it be that the weld had incusions or incomplete penetration at the root? Did anyone see any assembly pics of the cage and notice if the joints were fit up properly without large gaps? Did anyone pull the material ASTM and heat numbers from the material purchased to build the cage to see if the correct filler material was specified for welding these joints? I could go on but......I see lots of assumptions from just peering at a few pics posted online. I'm sorry but I just don't see how anyone can tell any of this from a few pictures.
DynoDon
10-27-2010, 09:22 AM
It did not hold up very well at all. The tube broke.
If you want to see what a properly welded cage does in a 100mph accident, look here:
http://corner-carvers.com/forums/showpost.php?p=836523&postcount=853
That car hit a wall at 80-100mph and the guy walked away from it with no injury. The cage deformed, factory spot welds split open, but at no point did any tube break off at the welded seam. The builder should thank his lucky stars that the driver was not killed, but to praise him for that work? Not a chance in hell.
Tyler
I did NOT Praise him, I suggested that the builder not be condemned based on looking at a couple of pictures. And to compare it to another crash is ludicrous, every accident is different and the points of impact are considerably different. Sliding sideways into a barrier is not like a multiple barrel roll and end over end flip. Obviously that Camaro had a well built and thought out cage but that is irrelevant to what happened in the Mustang.
I have been involved in racing since the mid 70's and was a licensed SCCA Tech Inspector for many years. I have built roll cages for many cars and some of those have been tested by their owners. I have seen plenty of examples of roll cages both doing their jobs, and not.
Did anyone put a fillet weld gage on those joints to determine if the welder used enough filler when tig'ing the joint up? Did anyone determine if the fillet weld size was engineered or did someone use a rule of thumb to size the welds? Did anyone use an electron microscope to see if the heat affected zone was too large or too small indicating that the welding procedure may have been at fault(heat input joules per in = amps x volts x 60 /travel speed measured in in/min). Did the fracture surface get examined by that same microscope to see if there are any indications that the material failed due to fatigue over a period of time or from multiple impacts during the wreck, or maybe if it just sheared in one quick impact? Could it be that the weld had inclusions or incomplete penetration at the root? Did anyone see any assembly pics of the cage and notice if the joints were fit up properly without large gaps? Did anyone pull the material ASTM and heat numbers from the material purchased to build the cage to see if the correct filler material was specified for welding these joints? I could go on but......I see lots of assumptions from just peering at a few pics posted online. I'm sorry but I just don't see how anyone can tell any of this from a few pictures.
Thank you! That was my point, too many people jumping to conclusions. I was not defending the builder or the integrity of the Cage, just stating that it is right for people to make statements based on looking at a picture without any facts. If the workmanship was faulty, then we all need to learn from it.
MrQuick
10-27-2010, 09:54 AM
well said. I agree.
vince
TitoJones
10-27-2010, 02:12 PM
I did NOT Praise him, I suggested that the builder not be condemned based on looking at a couple of pictures. And to compare it to another crash is ludicrous, every accident is different and the points of impact are considerably different. Sliding sideways into a barrier is not like a multiple barrel roll and end over end flip. Obviously that Camaro had a well built and thought out cage but that is irrelevant to what happened in the Mustang.
I have been involved in racing since the mid 70's and was a licensed SCCA Tech Inspector for many years. I have built roll cages for many cars and some of those have been tested by their owners. I have seen plenty of examples of roll cages both doing their jobs, and not.
Alright, how about this crash; it did involve end over end barrel rolls and surprise- no broken tubes.
http://www.autoblog.com/2010/10/12/video-opening-lap-crash-at-2010-bathurst-race/#continued
Skip to the 1:15 mark to see the initial wreck.
My point is that I don't need to see this stuff under a microscope to tell you that the weld was not adequate. The weld broke clean off the main tube; no tears, no sign of deformation, just a nice clean break that should not have happened. There are plenty of cages that have gone through that type of stress and not failed.
Tyler
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