This is why you don't skimp of safety... I've always loathed bolt-in rollcages, especially in C5s that have aluminum/balsa wood core floor pans. Hey but they pass drag racing tech so who cares right!

 

Like a guy said above if the floor is not properly reinforced with a plate this would happen with a bolt in or weld in cage.

 

Lets say I own a shop that builds full custom roll cages and someone comes in saying they want one but not to waste money on reinforcing the floor. What would you tell them? I'd tell them to get the fuck out. And I'm not sure how neither the driver or passenger, lol giving rides in a car like that, didn't get hurt. Kinda weird lol

 

its a ROLL bar, not a FLIP THROUGH THE AIR AND SMASH ON THE ROOF bar haha

 

That scenario is about the worst that could happen... a 4000lb poopstang doing a front flip right onto the roof. That said a properly engineered rollbar should be able to take it. Most bolt-in and kit "rollbars" are marketed as chassis-stiffening bars to do product liability.

A proper setup will integrate into the frame and have a diagonal bar for more strength.

 

Here is the problem with a bolt in cage/bar. The corners of the bottom plate. They act like an old timey can opener. Think of it like this, once a soda can has a hole in it you can tear it in half pretty easily. If the mounting plate had it corners rounded and a few welds it probably would have turned out better.

 

nice

 

The way the loads are spread into the chassis is very different between the two types of mounting. It still needs reinforcing obviously, but welding the cage is usually much stronger. It's rare that all the loads are only in one direction (perpendicular to the chassis for example) so usually there are loads in multiple directions, and those loads are applied through the bolts and through holes in sheet metal. Welding the plates spreads the loads across the sheet metal area, instead of a few bolts. Having something more than a roll bar helps also, because it constrains the directions that the loads can move.

The corner shape wouldn't matter much, you can punch a circular hole just as easily as a square hole, if the load is more or less perpendicular to the chassis.. The corner shape only matters if you're applying loads at an angle, because then all the force is concentrated in a small area into something like a corner versus an arc.. Another big problem is that the drilled holes are areas where tears can start, which is probably what happened in this case. The floor plates most likely ripped through the chassis starting at the weak (and rough) holes, instead of the whole floor plate punching its way through and making a clean square hole (which would happen if the corners were the problem).

The can opener analogy is awesome though, I love stuff like that.. It really is a perfect way of thinking about what happens in some situations.

 

Ouch... I dont wanna imagine the harness issue... >_<

 

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