Braking 101

["Mike Miller" <JoMi@email.msn.com>]

Do some of you more knowledgeable guys want to get technical and into the
physics of stopping a car? 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?
It seems to me that the kinectic energy contained in the forward motion of
the vehicle must be converted to heat and the bigger the mass (rotor) the
better to absorb/dissipate the heat. (vented rotors). I suspect pad compound
affects how much heat is transfered back to the caliper/brake fluid as well
as how much friction is applied to the rotors.
Obviously, tire adhesion is a major factor also as witnessed by the
increased stopping distances on wet/ice vs dry.
Anyway, now that I have exposed my ignorance, if some of you guys that know
way more than I want to step in here and educate the rest of us, it would be
appreciated.

mike
91 200q - UFOs that stop quickly
85 F250 4x4, Xcab turbo diesel - 6800 lbs that takes a long time to stop.