Re: Corrado Brakes -- Physics Question: Are they pointless?

[Riley McDowall <roog@home.com>]

At 4:45 pm -0500 4/2/99, 16V JASON wrote:
>The Audio 90 20v has the same brakes as the 16v Scirocco does: 10.1" in the
>front and 9.6" solid in the back, single piston calipers.  It weighs
>3200lb.  It outbrakes a stock Scirocco 16v.

Only because the tires, as a variable, aren't controlled.  How else could a
heavier car outbrake a lighter one, if both have the same brake systems?
Or is ABS another variable you haven't controlled for...

>The Mercedes S600, which weighs just under 5000lb (DOUBLE a 16v) and has
>389hp and 420lb-ft of torque, and which has to be restrained electronically
>from doubling the speed of sound :) can brake from 70-0 in 182 feet.... and
>does it with 12.6" rotors.

Jason, as I've already pointed out, rotor diameter is only one of MANY
significant variables in this equation.

>Okay.. Riley.. uh, I mean, this person with whom I have been debating this
>point offline, said that maybe the Mercedes uses a 2 or 4-piston caliper,
>which would help braking force.  That's a valid point.

Thank you for conceding this mostly-irrelevant point... :)

>True, the increase in swept area will give the brakes more initial bite..
>but (and now we come to my point), isn't the braking distance of a car
>limited essentially to the tires' ability to grip?  I mean, I'm sure I
>could do 200 km/h (125mph) in my 16v and lock my front wheels up instantly
>(not that I would want to, of course)... so what good would bigger rotors
>do? If the rotors can overpower the tires (which they can, if they can stop
>the wheel from turning), what's the point of having bigger rotors?

I'm weighing in with Shawn here.  I'm actually surprised to hear him
support 11" brakes on the list, since he's always been a big proponent of
tweaked 10.1s.  However, I've seen a lot of weird shit on the list today so
I guess anything goes!

He's right, there's more to braking systems than initial bite.  And he
makes a good point WRT CART (and F1 and pretty much every other
professional series) - by your logic, their brakes are massive overkill
since they can lock all 4 wheels at any speed they want, without
difficulty.  The whole point to moving up to the 11" Corrado stuff is their
ability to absorb heat and continue to work.

>So, with that said, and thus neglecting the fade factor, what's the benefit
>of upgrading to 11" brakes?  As far as I can see, the only benefits are
>fame (people saying "You're cool!"), and that's surely outweighed by the
>cost (ouch) and the increase in unspring weight.

You can't 'neglect' the fade factor.  There's no doubt at all that the
Corrado brakes will resist fade better than 10.1s, no matter what
fluid/pad/rotor/brake line combination we're talking about.  And Shawn and
I have first-person evidence that the 11s will give you shorter 70 or 80-0
stopping times.

The question of cost, however, is a good one.  Autotech wants $800US for an
11" conversion, which includes new pads, rotors, calipers, carriers, and
special brackets.  THAT is a rip off, I'll be the first to agree.  However,
they're not the only game in town, so to speak...



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