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Re: Autocross Gearing

To: Tyson D Sawyer <tyson@j3.org>, autox-cm@autox.team.net
Subject: Re: Autocross Gearing
From: Dick Rasmussen <rasmussend@mindspring.com>
Date: Thu, 20 May 2004 13:16:41 -0400
At 09:30 AM 5/20/2004, Tyson D Sawyer wrote:
>I tend to look at this the other way around.  Chuck setup our Reynard with 
>close gears and I haven't changed it.
>
>My take on it is that if you only have a few gears to choose from, you 
>will often find yourself on a course that is "between gears".  When this 
>happens, you have to keep shifting back an forth between two gears as you 
>fall of the bottom of one or run out the top of the other.
>
>If you have more closely spaced gears, you have a much better chance of 
>being able to select a gear that fits the speed range of a course or 
>section of course, then just leave it alone and drive the car.
>
>The other characteristic of close gears that I often hear (besides 
>lots-O-shifting) and also view differently is that closely geared cars are 
>run constantly at the top of the rpm range.  With widely spaced gears you 
>are forced to run to the top of the rev range before you can select the 
>next gear.  With closely spaced gears, the optimum rpm for shifting is 
>actually lower becase the next gear is "ready for use" sooner.
>
>So, I am a fan of closely spaced gears, but I like them so that I can 
>shift less and/or shift at lower rpm's.  This is opposite what I normally 
>hear associated with such setups.
>
>Cheers!
>Ty

Ty makes a very good point and it is exactly the reason I run a 66 mph 
second and a 78 mph third. I tried using a 60 mph second and a 70 mph third 
with a mid 80's fourth and found that for MY driving style, engine tuning, 
car setup . . . and most importantly the vast majority of the courses I ran 
that I was better off with my current setup which also uses a tall (46mph 
first) for the really slow corners. One of the things to sort out is 
whether you can use full throttle in the shorter gear before needing to 
shift. That's basically why I don't use the common mid 50's second gear. 
For me and my car, etc. there is no advantage to that gear. Obviously other 
folks do rather well with that approach!

One of the best things about CM is that we can do all this customizing 
without having to worry about getting too far into "left field".

Dick Rasmussen
CM 85
85 Van Diemen FF 

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