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Re: Gear ratios and autoxing

To: Kent Rafferty <gs96@sgi.net>, autocross list <autox@autox.team.net>
Subject: Re: Gear ratios and autoxing
From: Travis Lane <gofastlane@yahoo.com>
Date: Thu, 8 Jun 2000 10:49:36 -0700 (PDT)
--- Kent Rafferty <gs96@sgi.net> wrote:
> How does one figure what rear gear ratio would 
> be "optimal" for autocrossing?  Is there a "rule-of-
> thumb" for making this calculation?

I'll have a crack at this since I'm sorta interested as well.  Firstly, there
are a number of parameters to be narrowed prior to swapping any parts:

1) Are competing regionally or nationally?
   -Nationals courses are typically faster and will warrant a taller gear
   -Regional course design may be a factor

2) Will you be using 1st or 2nd gear primarily?
   -Do you have a very tall first gear (Viper, Ferrari, etc.)...
   -or a very short one (*blinks*, sorry, can't think of one)

In my Eagle Talon in DC region, I would shift into first at most events, but
almost never in SF region.

All that said, it's time to compromise.  Here are some things to think about:

a) You'll want to keep the car in the powerband as much as possible, of course
(perhaps more of a concern with Turbos)

b) It's OK to bang off the limiter (although I wouldn't recommend 1st gear in
a Geo Metro through the whole course)

c) Generically speaking, it's probably best to go a little taller on fast
courses (where you'll be limitting) and a bit smaller on tight courses (where
you'll be U-turning) and maybe taller and use 1st on the U-turns if the course
has both.

d) Most importantly!  You'll want to take a full pit crew and three rear ends
with you so you can swap after you walk the course.

I'd love to hear others' thoughts.

Travis


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