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RE: [6pack] autopower roll bar question

To: "Robert N. Clark" <rclark@robertsonclark.com>
Subject: RE: [6pack] autopower roll bar question
From: Robert Lang <lang@isis.mit.edu>
Date: Mon, 30 Jul 2007 13:24:47 -0400 (EDT)
Hi,

At the 1993 TRF Summer party, I was eyewitness to a TR6 rollover. The 
autox was at the airport and a driver who had not walked the course went 
out for his first run and got really loose in a slalom. When the car 
wiggled the other way, he went off driver's right into the grass with the 
car still rotating 'till the back of the car hit an embankment (stopping 
the motion of the vehicle). The car stood on the rear (I think the left 
rear dug into the dirt) exposing the entire bottom of the car and the car 
then rolled back onto the driver's side. The only thing keeping the car 
from turning turtle was the windscreen and the angle of the embankment, 
otherwise the windscreen would have pancaked.

Would a roll-bar have made a difference. Probably not. Would it have 
helped? In this case, not really. But had the car had just a slightly 
different "vector" it would have been ugly. As it was, the entire driver 
side was messed and two wheels were bent and the windscreen and frame were 
toast.

But to your question, it is extremely hard to flip a car, maybe even 
moreso with a low CG car like a TR6. But in real world driving, there are 
curbs, soft shoulders, ditches and all sorts of stuff that can make huge 
changes in the basic physics of a car in motion.

On the other hand, having a hard object to hit your noggin on is asking 
for trouble. Absent high density foam (not roll bar padding - real high 
density foam), even a minor shunt can result in various trauma including 
"closed head" injuries.

So you have to ask yourself - if the risk of your  head hitting the roll 
bar greater than the risk of rolling the car? That's something that only 
you can answer.

Ten years ago, if you'd ask me how hard it was to flip a car, I'd tell you
"it's pretty hard". However, I live in a major metro area (Boston, MA) and 
_every day_ there's a rollover somewhere in the traffic reports. We all 
know why - it's usually some person that thinks you can stop a high CG 
car/truck on a dime and make change while you're driving 75 mph. And the 
victim is usually someone that gets ping-ponged off the road. So it seems 
that the risk has increased. But for ME, I'd take the rollover risk vs. 
the potential to bang my head and skip the bar. I have a bar in the race 
car, but I wear head protection while I drive that (and I have 
high-density foam to reduce the intensity of helmet contact with the bar, 
per the SCCA regulations.)

That is all.
rml
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On Mon, 30 Jul 2007, Robert N. Clark wrote:

> I am interested in what TR6 owners are looking for when considering a
> roll bar for a non racing car.  Does anyone have any real life
> experience with rolling a tr6?
>
> Bob Clark
> 69' TR6




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