cross drilled rotors Scott Williams is WRONG!

[brett@netacc.net (Brett Van Sprewenburg)]

>brett,
>while the guy in the article is an expert  he had to simplify some stuff.
>while going to bigger calipers MIGHT requrie more fluid to make them move.
>they dont necc have to. For example IFyou could get the same volume
>requirement  for two calipers  ie. the same force for the same amount of
>psi as related to his article. getting a larger diameter system would be
>worth it. assuming there wasnt a significant increase in mass.

But if it resulted in the same clamping force, where is the win 
there?  I assume
you are talking about the heat handling properties that could be present?
I also believe you might have misspoke when you said larger diameter system,
I assume you are referring to having a virtually larger diameter through
multiple pistons?  Becuase, having a larger diameter of a piston given the
same input volume results in lower pressures being generated.

>ways that this can be accomplished.
>using multiple small diameter plungers. a light weight (xdrilled) rotor.
>so for most street applications the actual RIM that people use is going to
>effect thier unsprung weight more than the rotor. ie for a 30% increase in
>diameter and a 10% increase in weight.. its an acceptable tradeoff.

Sure, the rim probably has more affect as far as weight goes here, but this
discussion was primary aimed at braking systems, and getting after some
of the incorrect assumptions that many people have on how to improve it. I
totally understand that there are more forces at work here then what we've
talked about, or what was outlined in that article...but there were many
factors that were correct in that piece, which I do not think are 
well understood
by everyone...including myself before I started doing some actual research.

>esp if a light weight cooll looing rim is usea typical VW tear drop rim
>but remember the suspension geometyr on our cars was designed for that
>heavy ass wheel.

Actually, it probably wasn't...remember, it was pretty much the same as
far as basic geometry since 1974, when the cars were running fairly lightweight
13 inch steel or aluminum wheels.  Unless that's not what you were talking
about, or bunch or words got chopped off by your connection... :-)

>
>and he is also coming from a road racer point of view. not a dail driver.
>brian

Which I think is even more important actually...road racing can amplify small
problems in systems quite a bit.  That kind of driving can really find the
weaknesses in systems, especially braking.  As I mentioned in one of my
posts, most of the tweeking we do to our street driven cars braking systems
don't really matter as we generally do not drive the cars hard enough for it
to make a big difference.  It was just the misconception that many of us
that doing certain things were actually going to _increase_ performance,
which is what this has all been about.  That's not to say that changing or
updating the brakes on our cars isn't a good thing, as modifying your system
to tune it to how you like it, or freshening all the parts is obviously great.

Tuning it to how you like it can include caliper piston diameters, master
cylinder diameter, rotor dimensions, pad compounds, etc all factor into it.
However, we probably shouldn't say that changing these items is
a universal performance enhancement without understanding what variables
it's affecting, or how the braking system actually works.

==Brett

 \/  '84 Scirocco (ITB racer 2B) | "Hot VW's, take two home. They're small"
\/\/ '88 Scirocco 16v (Show), '92 Passat 16v (Winter+) | - brett@netacc.net