Re: Brakes in General

[Michael Spiers <mikes@specnet.com>]

> Good Question Mike,  Now try that same excersise from oh say 70mph 7
> times in 1 1/2 min. The stock brakes can't cool fast enough.

OK, so fade is due mostly to heat then, right?  And this increased heat is what
melts the pads right?  Possibly warping the rotors?  Can heat cause brake fluid
in the calipers to boil, and screw up all sorts of things too?  (Or is DOT 4
fluid supposed to prevent this...)  Also, what's the advantage of the dual
piston calipers I've got on there?  Heat dissipation, or clamping power
(possibly both?)  I'm assuming vents to the front brakes wouldn't be a bad
idea?  There's enough vents under that bumper, something should work.  If all
else fails, who needs those pesky front turn signals anyways, right?  (besides,
a little creative engineering would relocate them to the useless parking lights
in the turbo lenses anyhow...)  Also, rim design.  I know rims help brake
cooling if designed right, and aluminum is the best way to acheive this.  Is
this because they're (the rims) designed to pull air over the brakes when the
wheels are spinning, or because the rims are designed to dissipate heat away
from the brakes?  Possibly both??  Can the size of the rim help or hurt?  I.E.,
a 16X7.5 rim can dissipate or cool or whatever better than a stock 15X6 can?

> Last August
> at the Blackhawk event I was Working with Brian Collins trying to get him
> to use his brakes more effectivly.  When we came into the pits after 2
> cool down laps we shot the Rotors, Calipers, and wheel face with a
> Optical Pyrometer and got some absoultly terrifing temps.  Rotors Over
> 880F, Calipers 650F, wheel face 350F.

When Brian was racing at Summit Point this September, he had the same problem
(multiplied by a screwed accumulator.)  One of the turns he went into almost
landed him in the trunk of a 944.  He came in the pits, we jacked up the car,
and you could see the cross-drilled holes full of brake pad remnants.  This
seemed really extreme, none of the other cars had this extent of heat damage
('course, Brian was hauling around the track faster than most others, but
still...)  Could this have also had something to do with the fact that his 200
is three inches closer to the ground than it should be?  Complicated by that
skirt he's got on there blocking air flow to the brakes?

> So. The Q's are way
> under-braked IF You are going to take the car on the track or do some
> spirited street "Touring".  If you ONLY drive on the street you SHOULD be
> okay.... But the Moment that you upgrade the HP your on the line brake
> capacity wise.
>
SO, since Ned's had his hands in my box and spring perch, you're saying...
  Umm, OK, I think I get the picture...

-- 
-Mike
mikes@specnet.com
mks107@psuvm.psu.edu
87 5000CS TQ
84 5000S (2,000 miles away and a mile high)
90 80 (sibling's mode of transportation I get lynched into working on)