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Re: Re[2]: Roadster gear ratio's

To: <Fred_Katz@ci.sf.ca.us>,
Subject: Re: Re[2]: Roadster gear ratio's
From: Ronnie Day <ronday@home.com>
Date: Fri, 9 Feb 2001 14:22:11 -0600
>No, I said it changes the effective gearing ratio, not the actual gear 
>ratio. As Adam said, I'm making the case that the effective gearing ratio 
>changes so "2.957 in 1st with 3.70 rearend rotates the tire at the same 
>rate as 3.117 in 1st with 3.90 rearend". You put a different rear end in, 
>you get a different effective ratio in comparison with the stock setup.

Fred,

I was confused by you math:

2.957 x 3.7 = 10.94  and
3.117 x 3.9 = 12.16

Then I "swapped" rear end ratios in the calcs:

2.957 x 3.9 = 11.5323
3.117 x 3.7 = 11.5329

Is the second set of calcs what you were trying to point out or has my 
trumpet player brain gone on walkabout again? <grin> If I am doing the 
math right, then dropping a 5-speed into a 1600 along with a 4.38 rear 
end yields a 3.7 in 5th (.85 to 1). I didn't do the overall drive ratio 
through the gears to compare the 4-speed/3.90 combinations comparing the 
5-speed/4.38 set. It might result in a basically useless first gear. 
Except in San Francisco maybe.

Bottom line, I've always thought it was the final overall ratio in each 
gear that really mattered, and tire diameter (deceased or otherwise <G>) 
is always a factor, too. When we first ran the Goodyear 22 inch slicks in 
Hawaii I was amazed at the difference they made not only in the corners, 
but in acceleration AND engine braking, too. 

Ronnie Day
ronday@home.com
Dallas/Ft. Worth
'71 510 2-dr (Prepared Class Autocrosser)
'73 510 2-dr (Street Toy)

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