From: emory!Eng.Sun.COM!Scott.Griffith (Scott Griffith, Sun Microsystems Lumpyware)
X-Source: The Hotrod Mailing list
Date: Mar 1993
Subject: Safety belts

On Mar 22, Dave Williams wrote:

>  Whether the sub straps would be useful depends more on seating position
> than anything else.  Sub straps also require chopping into your seat,
> with the requisite mods to any internal bracing or springing, and
> upholstery work.  

Well, sort of. I hate to get into this, but I feel that I have to
anyway as the token cornerworker/driver on the list.

The sub strap's real purpose has nothing to do with seating position.
Its only purpose is to keep the buckle down on your pelvis (which has
enough structure to take the brunt of an impact), instead of allowing
the shoulder belts to pull it up onto the unprotected abdominal
muscles and soft tissues beneath. Its primary purpose is _not_ to stop
you sliding out under the belts in an impact by snagging you by the
'nads, as most people think. The nasty thing is that the SCCA GCRs
specify belt mountings that don't do this buckle location very well,
so that people have slack in the sub strap- and the buckle still gets
hiked up onto their solar plexus. Useless. That's why most folks don't
care for sub straps- they don't understand them, and they've driven
cars with bad installations.

This can lead to the drivers leaving their shoulder belts slack, which
means they peg the wheel with their chin when they meet Mr. Tirewall.
Or, alternatively, they run the shoulder belts tight, and end up with
"Simpson" tattooed on their livers. Internal injuries still happen
despite all the efforts to the contrary- I've packed enough drivers
into ambulances over my years as a flagger to know. And it's a damned
shame, and it's almost totally preventable.

So in my track car, I use 6-point belts, and run the twin sub straps
_aft_ to the lap belt mount points. I still use my unmodified stock
seats, so I feed the sub strap up through the joint between back and
bottom (NO modification required), and sit on it. In this position, it
does an excellent job of keeping the buckle down right over my pelvis
where it belongs, and guarantees that I can pull the shoulder belts
tight enough to keep my face off the windshield if I make the Big
Mistake. I run the belts _tight_, which is a leftover from my days
driving an F2000 car where _breathing_ was optional while belted in.

There are a lot of SCCA legal, well prepped race cars out there with
unsafe belt installations. Primarily because people just slavishly
follow the rules, instead of thinking about exactly what the belts are
trying to do for them. 

Hope that this clarifies things a bit, and doesn't add fuel to the
flames. Think carefully about what your belts are actually trying to
do for you. The aircraft analogy breaks down a bit, because 100G
decelerations are considered bad form in aircraft (well, excepting
possibly naval aviation!), but are an all-too-common occurrence in
motorsport... Use a sub strap, install it well, and save your spleen.

-skod

--
Scott Griffith, Sun Microsystems Lumpyware
expatriate SCCA New England Region Flagging/Communications worker
(and sometimes driver, of anything that turns both right and left,
and can pass tech...) Return Path : skod@sun.COM