[s-cars] Stopping - Tire patch questions/threshold braking

[Dave Burig]

At my very first driving school at Mid Ohio I was taught the technique (with
ABS fuse pulled) of braking hard enough to momentarily induce lockup, then
curling the toes of your braking foot forward, which slightly reduces pedal
effort.  With practice, I learned to hit that "sweet spot" where you could
just barely hear the "scuff scuff" of tires at impending lockup right up to
the moment you stop.  It was my experience that you could beat the full ABS
braking distance without much problem.  Different matter in the wet...I
never got that good.  That was with stock brakes.  Upon installing the Big
(Black) Reds, hitting that point is MUCH easier, threshold is easier to
maintain, and I can do it over and over again without fade.  If you are
considering the upgrade to Big Reds with Mintex pads, the above technique,
when practiced several times per month, is an effective way to keep the
squeal away. ;`)

DB

-----Original Message-----
From: s-car-list-admin at audifans.com [mailto:s-car-list-admin at audifans.com]On
Behalf Of Richard Tanimura
Sent: Thursday, October 02, 2003 12:26 PM
To: Linus Toy; 'Sean Douglas'; 'Lewis, Gary M'; 'S-Car List'
Subject: RE: [s-cars] Stopping - Tire patch questions

Linus wrote ..

My understanding is that best acceleration (negative accel=braking) is with
the
tire just slipping...about 5% or so.  Keeping a tire on that threshhold is
the
key, and (generically speaking) the reason to install better brakes on a
street
car even for the one stop situation--better brakes in this context meaning
brakes that give you better feel and modulation of braking pressure than you
get from stock brakes, so you can hold that pressure point.  Yes, the Big
Reds
definitely improve that feel over stock.

....

Your understanding is quite the same as mine. The simple reason is that the
coefficient of rolling friction is higher than the coefficient of sliding
friction IIR high school physics correctly. Just below the threshold of that
transition is the optimal point.

I don't know if I follow you on the modulation. On my car w/o anti-locking
brakes modulation is important. But on my S2 with anti-locking brakes on the
car I don't understand the need. You can stomp on the brakes as hard as you
want and the electronics do the modulation for you i.e. keep you at or near
the threshold. Or am I missing something as usual?

Rich
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