I've never posted to the list before though I've been lurking for over a year
but...
I helped Matt install this harness bar so I kinda have an interest in the
subject.
As far as comparing his harnes bar to a strut tower brace, it is not a direct
comparison.
Most strut tower braces DO have triangulation... in a sense...
Note the mounting points... they are usually circular pieces of flat stock with
at least three bolts (per side) that match up to the bolts securing the strut.
Didja hear me write "three bolts"? Three mounting points (without flex or a
pivot involved) means triangualtion.
Thus the strut tower bar with three bolts per side (or even 2 bolts per side,
total 4, that's more than three) will provide some prevention of chassis
twisting.
Matt's harness bar on the other hand is a U-shaped bar, (with one end bracket
bolted on so that it can be maneuvered into place) bolted to the car with the
stock (upper) shoulder belt bolts with two downrods bolted to the seat mounting
bolt. Of some significance is the fact that these downrods have rod-ends at
both ends. Thus they are completely free (minus unavoidable operating
friction) to move in all directions except the one that keeps the harness bar
at its desired height.
So, apart from placing an elephant on the roof of the car and trying to "bow"
the B-pillars, attaching chains to the B-pillars and trying to tractor-pull
Matt's M3 apart, or squeezing the poor thing between a couple of Sumo
Wrestlers, AND the infinite variations on force providing implements to
accomplish the same tasks as I just described... can you concieve of a
situation in which this particular harness bar would serve any purpose other
than to hold the harnesses (and his in-car camera) in place?
-STEFAN ...one of the few remaining Saab-devoted autocrossers
In a message dated Tue, 20 Mar 2001 8:36:47 AM Eastern Standard Time,
Andrew_Bettencourt@Kingston.com writes:
<< Matt has the right idea. We need clarification. perhaps an SEB member can
shed some light on the *intent* of the wording change. In my mind,
anything that is bolted from B pillar to B pillar without telescoping
action *IS* providing additional structural rigidity - however nominal.
I'm also no physicist, but non-triangulated strut tower braces provide
structural rigidity - or they would be TOTALLY cosmetic, so that idea
doesn't fly with me.
The gray area in my mind is simple: why change the wording of a perfectly
clear rule unless you intend to change the intent, and if that was the
goal, why not just make it clear?
AB
"matthew c.
mead" To: Snapspinnr@aol.com
<mmead-autox@goo cc: autox@autox.team.net
f.com> Subject: Re: harness bar
legality in stock?
Sent by:
owner-autox@auto
x.team.net
03/20/01 07:59
AM
Please respond
to "matthew c.
mead"
On Mon, Mar 19, 2001 at 09:51:48PM -0500, Snapspinnr@aol.com wrote:
> Harness bars are specifically allowed in stock. There is a line in the
stock
> rules about them. And this year the SCCA did change the wording of the
rule
> so that "telescoping" harness bars are not required.
It seems that since the word telescoping no longer exists in the
rules, and there is no triangulation involved in the design of this
harness bar (just downrods on either side to keep it from changing
height) which might add structural rigidity, it's legal. I may
have to call the headquarters for an interpretation, though.
-matt
--
matthew c. mead
mmead (at at at) goof (dot dot dot) com (you know what to do to email me)
http://www.goof.com/~mmead/
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