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Re: Panic Stop

To: "Datsun Roadster List" <datsun-roadsters@autox.team.net>
Subject: Re: Panic Stop
From: "Graham Evans" <evansg@erols.com>
Date: Thu, 11 Nov 1999 11:49:27 -0500
>From everything that I have read, the facts do not bear out ABS stopping a
car in a shorter distance.  In fact, the contrary seems to be the case as
was pointed out in the California Highway Patrol tests.  The real benefit to
ABS brakes is that the help prevent the car going into a skid and losing
control of the vehicle, hence the nomenclature ABS for Anti-lock Braking
System.  As I understand the problem, ABS prevent skids by sensing the wheel
that is locking up and reducing the brake pressure on that wheel.  While
this avoids the skid, it results in an overall loss of braking efficiency
since the affected wheel is no longer braking at full force.  This can
amount to a loss of up to 25% for the period of ABS engagement.  While the
period of engagement is brief, the overall effect is a reduction of braking
capacity.  Net result, you stop in a straight line, but takes a slight bit
longer to stop.  For the average driver this is probably the better trade
off since fish tailing and loss of control are more likely to cause an
accident, but then roadster drivers aren't average, are they ;)

Graham
68 1600

----- Original Message -----
From: Gary McCormick <svgkm@halley.ca.essd.northgrum.com>
To: Datsun Roadster List <datsun-roadsters@autox.team.net>
Sent: Thursday, November 11, 1999 11:06 AM
Subject: Re: Panic Stop


> Wow! I had no idea I was going to stir up such a storm of controversy with
my post
> regarding ABS.
>
> For all you GM vehicle owners out there - I did say "GM quality control
issues aside".
> GM's system may "suck", as Fred so eloquently put it, but that does not
change the fact
> that the theory behind ABS is sound. It is simple physics - there is less
friction force,
> therefore less braking, at the interface between a sliding tire and the
pavement. And
> don't talk to me about "hot racing rubber" - I'm not talking about a
nicely warmed up,
> high tack racing tire - I'm talking about a sliding tire that is shedding
rubber
> particles, generating it's own little patch of roller bearings between the
body of the
> tire and the pavement.
>
> The fact that insurance companies don't like ABS is no showstopper,
either. Yes, repair
> rates will go up, for the exact reason that Paul Kort cited - but the
brain trust in the
> insurance industry were also initially leery of ABS because they were
afraid that
> ABS-equipped cars would be rear-ended more often when they stopped quicker
than the car
> behind them.
>
> While it is true that a skilled driver in a vehicle with a braking system
in good nick can
> brake as well (or nearly as well) as a vehicle with a well-designed (like
BMW's) ABS
> system, face it - that kind of capability is only found behind the
steering wheels of
> about 10% of the vehicles on the road. Like it or not, automobiles are the
transportation
> system of the masses in the US, and even those who have the reflexes and
the latent
> capability need training to develop that skill.
>
> There is no need, however, to bring the subject of airbags into the
discussion. Frontal
> airbags are designed to protect people who are too ignorant to implement a
simple,
> effective safety device - the seatbelt - from themselves. ABS brakes, when
PROPERLY
> DESIGNED, allow a vehicle's brakes to operate in their most efficient
operating regime
> without the requirement of a high level of skill on the part of the
vehicle operator.
>
> Gary McCormick
> San Jose, CA
>
>


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