On Thu, 12 Mar 1998, Allen Nugent wrote:
> Bob,
>
> At 12:36 11/03/98 -0500, you wrote:
>
> >... A racing pad needs to come up to
> >temp before they will work. For your typical street driver, the pad would
> >not even come close to operating temps before you hit other cars and
> >objects around you...
>
> You sound much better informed than I, but I think you're being too general.
I am purposely being general. I'll restate: racing pads on the street are
a bad idea. That having been said, I'll be a little more specific.
By the way, I am hardly an expert on brakes, so anyone can chime in if
they know more.
With brakes, any brakes, the amount of friction between the disk and the
pad changes as a function of the temperature of the two materials. The
friction that can be measured between the rotor/pad is referred to as the
coefficient of friction (COF).
Now, the COF changes as a function of temperature. As the temperature
changes, the COF can go up _or down_. When it goes up, the pads grab
more, when it goes down you have brake fade. Further, the COF vs. temp
curve is linear - but the ramp up to max. COF and the fall off from max.
COF might be really steep.
So, racing pads tend to have little friction when they are cold to warm
and then have a lot of friction when they get hot. When they get too hot,
you're in deep do-do. On the other hand, street pads will work when cold
or warm but will tend to fall off in thier COF as they get hot or too hot.
> I have what were sold to me as "racing pads" on my TR7. They only take a few
> minutes of normal driving to come up to temp. In the meantime, I just drive
> slower and/or push harder on the pedal.
These are probably "metallic" or "semi-metallic" pads. Brake guys also
call them "hard pads", they tend to give you a much "harder pedal" feel
when you step on the brakes.
> Perhaps I'm using a compound that's somewhere in between road and full-race.
> I'll have to find out. (They're on Ford Capris disks/calipers, anyway.)
See above.
I'll bet the Capris calipers work very well on your TR7...
> Allen Nugent
regards,
rml
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