Rollcage issues

[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.

[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