Rollcage issues

[bret]

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

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]

Get it certified yet?

[DynoDon]

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]

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]

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]

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]

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]

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]

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.

[bret]

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]

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.


I'd hate/cringe to speculate what would have happened without a cage.

[overZealous1]

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]

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]

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]

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]

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]

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]

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]

Right, how much is enough and failure is only measured by failure. nice point Bill.

[bret]

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.