Monday morning, and I thought I might chime in on this thread.
Let's not get carried away with rollbars. There are reasons for street type
roll bars and reasons for competition ones. Each only gives a modicum of
improved safety. I am sure we have all run into cases where specific
incidents contradict all the benefits.
The street roll bars that are currently available from reputable
manufacturers will definitely improve survival chances in the case of a
sports car making a typical soft roll on a hard surface, if the driver is
wearing a shoulder harness that has locked. It will also improve the
chances that the vehicle will continue into a complete roll rather than
landing upside down and trapping the occupants. A roll bar could possibly
save a life if something was trying to come into the car and get cosy with
you, such as a grand piano or tree. Then again as Gerardo noted, since in
normal driving you are not wearing a helmet, there is the liability that you
may strike your head on the roll bar structure in other types of accidents.
Comparing a street roll bar to a competition one is I believe acompletely
useless excercise. A street roll bar is designed to fit under a top, a
competition one (in a convertible car) has no such need. Comparing 2" here
and there, or an extra cross brace is really academic when it comes to
actual crash incidences. The human body stretches a long way when under the
forces involved in a collision of any type. A competition roll structure
has just as many limitations as a street one if the driver is not wearing a
helmet, tight belts and arm restraints. A roll bar of either type only
serves to increase the odds, while hopefully not adding dangers.
I have seen a street roll bar in a TR6 that saved the driver's life when the
car went off a cliff and did 7 barrel rolls. I also knew a race driver who
was killed instantly when his car flipped once and landed on a flower
planter.
This is what I have observed after working in a British Scrap Yard for a
number of years.
1. Sports cars don't roll easily. They tend to be really stable and hard
to flip, so a street roll bar is not an essential piece of kit unless you
intend to compete with the car (or just look like you do). I have seen over
1000 wrecked British sports cars, only three were involved in roll overs.
2. Most fatal sports car accidents were the result of the occupants not
wearing seat belts, in most cases the passenger compartments were still
secure. There is a lesson here. Without good seat belts a roll bar is
absolutely useless.
3. The available Street bars offer as much "real world" protection as race
bars. If something is going to reach in and touch you, an additional 2"
from an unprotected head is not going to do you any good at all. I have
seen some pretty bent street bars, but none that have collapsed.
4. Last of all. If your ticket is up, it's up. Reference Dick Criswell's
accident. I've got a roll bar for my MGB GT, but I feel kinda silly
installing it after seeing Dick's car which looked like the god's took an
almighty baseball bat to the driver's area.
If we were really that worried about safety I think we had better stick to
MGB GTs with full cages and side intrusion bars.
all the best
Kelvin.
> "Brinkman, Gerardo V" wrote:
> >
> >
> > My personal opinion, is that roll-over bars and cages
> should designed
> > and built to suit each individual person/car combination. I
> do not believe
> > that an 'off-the-shelf' roll-bar suits everyone. Case in
> point, my Midget
> > had an 'off-the-shelf' roll-over bar and I was rear-ended
> by a Minivan
> > (< 5mph). my head went backwards and struck the top of the
> roll-bar. I
> > was knocked out by the very item that was supposed to
> portect me. i ditched
> > that roll-bar and had a custom roll-bar fitted which was 2
> inches higher and
> >
>
> Hear, hear! Oh dear - a pet topic of mine.
>
> Since my involvement in motorsport, especially as an official, I look
> into the rules and regulations to find how and why they were
> formulated,
> and now even if I could get away with it I tend to stick to the
> regulation safety features because there is generally research and
> scientific proof behind their required designs.
>
> ROPS (Rollover Protection Structures) regulations here require the
> rollbar in an open top car to be 50mm (2") above the driver's
> head - top
> of the helmet. Also required are two backstays and a diagonal/cross
> member (there are lots of other requirements that I won't go
> into here).
> That is how my rollbar has been constructed and it means I
> can't fit the
> soft-top on the car (because of the height and because the rear stays
> prevent the operation, collapse or stowage of my midfold top)
> but I feel
> mightily safe under that thing both on and off the track.
>
> I see all sorts of "off the shelf" rollbars on MGs that don't
> comply to
> these standards and despite people telling me that they have them for
> safety and not looks, how safe can a rollbar be if it is
> going to allow
> your head to make contact with the ground if your car rolls over (some
> people's heads protude well ABOVE their rollbar when they are strapped
> in!) or if the rollbar simply collapses under the impact and weight of
> the car - adding to the impact of everything else on your head/neck?
>
> Eric
> '68 MGB MkII
> '85 Rover SD1 Vanden Plas
> Adelaide, South Australia
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