Re: 16V Scirocco (tranny blow up)

[Scott Williams <sfwilliams@home.com>]

16v Jason is absolutely right about this for every reason. There is no way that
you can exceed the traction limitation of your tires. Let's say that the maxium
braking force applied by friction *between the tires and the ground* (your engine
doesn't directly stop your car unless it is dragging on the ground.) can be
expressed numerically as a value of 1. Assume also that your brakes are powerful
enough to put the number up to say.. 1.25. What happens, the braking force exceeds
the available traction and the car slides.

Now, let's use the engine to help slow the car. All braking force generated by the
application of engine compression transmitted *to the tires* via the drivetrain
comes to a number of the magic value of 1. Okay? What happens? The car slows at
100% of it's max decelleration rate. Right. Now, downshift to a lower gear and
increase the braking force to 1.25 again. What happens now? The car looses
traction and slides forward all over again. Consider what your theory assumes,
that engine braking transcend the laws of physics.

See, it really is a matter of how much traction you have. Period. Engine braking
will never increase the amount of available traction that the tires can generate.
Stickier tires will help. A driving surface with a higher coefficient of friction
(asphalt vs. ice) will help. Engine braking does nothing for you except for
instances where you don't have *enough* brakes to do the job..

If you can stomp on the brakes and lock them up, good! Now you know what the
braking threshold is. And it is a hell of a lot easier to modulate your
decelleration rate with the brakes than it is with the clutch.

Okay, let's directly address Mr. Snow's analysis:

> 1.) I have a someone following me into a curve, let's say I don't know,
> YOU...your right on my ass, I hit the brake, because I am going faster than
> I should, now your even closer
>
Yes, I'm even closer for that very moment only if I've waited too long to brake
also. Everything else equal, I'll have to slow down just like you in a moment. And
then you've regained the same lead that you had before.

> , and let's say, my brakes lock...DOH! now we
> are both floating around with harps...
>
NOT if you *modulate* the braking force with your foot on the brake pedal.
-something that you can't do effectively with engine braking.

> OR I downshift, let the car hold itself back
>
There's nothing wrong with *downshifting*. You must do it to stay in your
powerband. However, you're forgetting the revmatching part of the equation. The
ideal is to downshift and create a netzero effect on the decelleration rate.
SMOOTHNESS is key. It all becomes liquid when you're doing it right.

> and now at the end of the curve, I am stabbing the gas,
>
Check the vocabulary. You shouldn't be stabbing anything. I don't know whether
that was just a matter of expression or whatever, but a very smooth application of
power is what you want. Forgive me if that was just a semantic issue and not a
critique of your real technique.

> AND I am in a lower gear, if you use your brake, you are
> wondering why I am 3 or four car lengths ahead of you.
>
Nope, I did my braking earlier in the turn and the used the excess traction that I
had left over for cornering force. I then passed you on the inside of the turn
while you were scrubbing off speed. Since I have also kept my car in the correct
powerband I then rocket past you while you consider the math.

Yes, I'm being mildly sarcastic. Don't be offended; I'm just having a little fun
with this.

> 2.) Downshifting [and engine braking]into a curve is better than braking.
>
No it ain't! Think about it.
--
Scott F. Williams
NJ Scirocco nut
SCCA ProRally driver
Hotrod Rabbit GTi


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