Roll Bar in a street car discussion Options

[Scott S]

Hi All. I posted this over on Pelican, thought it might be relevant here too.

I know there have been many discussions on the safety putting a roll bar/cage in a street driven car. I am not a racer, so it really didn't pertain to me at all. However, yesterday I saw first hand the injuries that can occur.

16 year old girl driving her dads Miata with him in the passenger seat. There is speculation that she was driving on her permit, practicing for her drivers license. She was driving at a slow speed, simply making a right hand turn on to a side street. She clipped the curb - something we all have done. Curb was tall enough that it shook the car pretty good (again, speculation, but knowing the corner I would guess a wheel would have been bent and the car knocked out of alignment ).

Both are in the hospital with concussions, one of them needed several stiches from injuries caused by their heads impacting the roll bar.

I don't know if the dad autocrossed the car or what, or if the bar was just for looks. I do know the car had stock seat belts.

Scary stuff.

[DBCooper]

But I never said that, Andy. Did you read the first post in this thread? Bumped a curb and two people in the hospital? That's not a big enough deal? Like I said, do whatever you want, but people do get hurt so don't make that choice without at least knowing the issues. That's not fair? You think it's better to not talk about it at all?

[SirAndy]

But I never said that, Andy. Did you read the first post in this thread? Bumped a curb and two people in the hospital? That's not a big enough deal?

But that wasn't in a 914 and we don't know how that cage was build and how far their heads were from the cage and if it was padded.

That's A LOT of unknowns to make such a blanket statement!


What i am telling you is that in my car my head is no closer to my (padded) roll bar than it is to (covered) solid metal in my daily driver sedan.

I still have no idea why you insist that one somehow is going to kill me while the other one is perfectly acceptable?
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[DBCooper]

But that wasn't in a 914 and we don't know how that cage was build and how far their heads were from the cage and if it was padded.

That's A LOT of unknowns to make such a blanket statement!

Not really. Without a roll bar there was nothing there for their heads to hit. They added a bar TO THE SAME CAR, there was then something for their head to hit and they hit their heads. IN THE SAME CAR. They changed the car and the change made it less safe.

What i am telling you is that in my car my head is no closer to my (padded) roll bar than it is to (covered) solid metal in my daily driver sedan.

Yes, you did say that, but again, the comparison I've made has been in the SAME car. Before adding a bar (in any car) there's clearance, adding the bar reduces the clearance IN THAT SAME CAR, so your head can then hit where it wouldn't have before IN THAT SAME CAR. It's had a hazzard added so in that aspect is less safe than it was before.

I still have no idea why you insist that one somehow is going to kill me while the other one is perfectly acceptable?
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I never said that even once, so certainly never insisted. From the beginning I've said that adding a bar or cage changes and reduces the clearance IN THE SAME CAR. Your other car can have airbags, be the Queen Mary or a blimp, it's irrelevant because I'm talking about the addition of a bar/cage changing the configuration IN THAT SAME CAR.

Look, you don't get anything for free. A roll cage can make your car stiffer, may protect better from being t-boned, from rollover and so on. But to get something you have to give up something, and that something is contact with your head. If that works for you, great, as long as you're aware of it and accept it it's not a problem, but it's not rational to pretend that it doesn't exist.

[SirAndy]

What i am telling you is that in my car my head is no closer to my (padded) roll bar than it is to (covered) solid metal in my daily driver sedan.

Yes, you did say that, but again, the comparison I've made has been in the SAME car. Before adding a bar (in any car) there's clearance, adding the bar reduces the clearance IN THAT SAME CAR, so your head can then hit where it wouldn't have before IN THAT SAME CAR. It's had a hazzard added so in that aspect is less safe than it was before.

But why is the exact same distance a hazard "IN THE SAME CAR" but not in another car?

I just don't get it ...

Why did my 914 become less safe when the distance from the rollbar to my head is no closer than the distance from the door-frame on my Jetta to my head?

What makes that same distance an acute "you're going to die" hazard in a 914 but not in a Jetta?
I am profoundly confused by your logic.

You fully accept the margin of hazard in my Jetta but when i add something to my 914 that brings me within the same margin of hazard, it's instagib brainmush unsafe at any speed.
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[DBCooper]

Why did my 914 become less safe when the distance from the rollbar to my head is no closer than the distance from the door-frame on my Jetta to my head?

I didn't say that Andy, you did. Re-read the first post. The discussion was about wisdom of adding a bar or cage to a street car, in other words modifying the SAME car, before and after. I have no idea about Jettas, but wasn't your Jetta designed by an engineer specifically for passenger survivability? Different seats and belts? Cabin crush differently? More and different pladding inside, all different materials? Have airbags? In fact EVERYTHING about the car acting differently in a crash? It's not as simple as clearance distance, your question is about apples to oranges, and the answer is 'who knows?' Which is why the discussion was about putting a roll bar into a street car and not why Jettas are safer than 914's. That's a totally different discussion.

I am profoundly confused by your logic.

You fully accept the margin of hazard in my Jetta but when i add something to my 914 that brings me within the same margin of hazard, it's instagib brainmush unsafe at any speed.
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Again, I never talked about Jettas. But by the same before/after logic if you did add a roll cage to your Jetta you're creating exactly the same situation with your Jetta, by reducing clearances. More hazard than a 914? I don't know, can't know, you'd need to talk to someone else about that. But more hazzard in the Jetta with the cage than without? Before and after? Yes, the same logic applies, and worse, if you block the Jetta's airbags.

My point has been that with that modification you're reducing clearances in THAT car, be it 914 or Jetta, which, by itself, makes THAT car less safe, before and after. In a race car you have a race seat, restricting movement, race belts, restricting movement, and a helmet, for exactly the type of impact described in the first post. If you add all those things to the street car along with the bar/cage then yes, safer. Without them the bar/cage adds a new safety hazard to the same car.

I didn't invent any of this, you know it all already because it's conventional wisdom. So is conventional wisdom incorrect? How is that?