Rollcage issues

[LeighP]

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]

NHRA rules are 2" over the drivers head and no more than 6" behind.

[mike w.]

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]

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

[bret]

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]

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]

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/sho...&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]

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.


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]

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]

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/sho...&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]

well said. I agree.

vince

[TitoJones]

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/v...ace/#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