Re: Harnesses & Rollbars

[Scott Blazey <edpm3@xxxxxxxxxxxxx>]

Robb writes :  >><fontfamily><param>Times</param>... I just recently
installed 4 point harnesses in my E30 325is and egads, I don't have a
roll bar. <<snip>  The inside shoulder straps, right for driver and
left for passenger, have a design feature which lengthens the strap
under a certain force. That in turn enables a "tuck before your head
gets squashed like a bug" maneuver. 

>

>How much force is required ? I don't know. How does it work ? I don't
know. Will I get a roll bar ? Yes someday, but for now I'm going
sans-bar. <<<<



The Schroth technology Robb refers to is called ASM (Anti
Sub-Marining). It is not described by Schroth as a "tuck before your
head gets squashed" device; rather, it is designed to force "the
driver's torso and hips to rotate slightly into an asymmetrical posture
which tightens the lap belt milliseconds faster and helps  minimize the
risk of submarining (sliding violently beneath the lap belt)." So,
while the Schroth ASM feature causes the river's upper body to twist,
it does not necessarily allow it to move to the side and down, thereby
avoiding having one's spinal column become the roof's new B-pillar in a
rollover/roof collapse. Diagrams and photos in Schroth's literature
depict drivers remaining upright in such situations. With or without
ASM, the driver is going to remain essentially upright in the seat;
that's the primary function of four-point (or five- or six-point)
harnesses.


I'm aware of the attraction such harnesses have for drivers who
frequent the track or run autocross, and they certainly do keep you in
your seat and behind the wheel more firmly, and improve your ability to
control the car. However, if you have four- (or more) point harnesses
without a roll bar/cage, please follow this simple safety rule:  Don't
roll your car.


Scott

('95 M3. Harnesses by Schroth. Rollbar by Kline.)




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