Re: Braking 101

[DeWitt Harrison <de@aztek-eng.com>]

On Thu, 2 Apr 1998 11:44:31 -0800, Mike Miller wrote:
>[ ... ]  I was watching a discussion elsewhere where it
>was said that all brake pads are the same for stopping a car and that what
>really matters is the tire.  Here's the actual statement:
><begin statement> <snip>
>Putting a Brembo system may alter how much pedal pressure is necessary to do
>the same thing, but it can't alter the actual results. There's an ad on TV
>now for some brake pad that mkaes the claim that no
>other pads can stop the shown vehicle (a Suburban) faster than their brake
>pads. Why? Because they all stop the thing at the same rate, because that
>rate is a function of the tire adhesion (traction), not the brake pads.
><end statement> <snip>
>If that were true - why would people spring big bucks for 4 pot calipers,
>330 mm rotors, carbon kevlar pads, etc...These things help for repeated
>stops as in track use, but what about that one time panic stop on the
>freeway? If I can lock up the existing brakes easily, what will be gained by
>the above?
>[ ... ]

Simple. There is a huge difference between one high speed stop and
even just a couple track laps worth of decelerations from speed. Stock
brakes just can't get ride of heat fast enough. You are on the right
track, but it's not so much a mass thing as it is an area thing.

Slapping in hi po pads helps on the short twisty tracks, but long
straight tracks - e.g. two or more 100+ to 30 mph events per lap - will
eat up the most expensive pads in just a few laps with stock brakes
(unless your daily driver is a 993 or whatever).

Keep in mind that wider than stock tires have typically been installed.
It's reasonable that the brake size would increase to match. It should
also be mentioned that big brakes make it easier to modulate braking
force with precision.

DeWitt Harrison    de@aztek-eng.com
Boulder, CO
88 5kcstq