So was I. What I meant to say was "With a 5-speed the 2.957 in 1st with a
1600-3.90 rearend rotates the tire equivalent to a 3.117 in 1st with 3.70
rearend". Yeah, I swapped the numbers in the latest message!
I got a reminder that speed is nice but not to get carried away. On my 300ZX the
other day I had to take a left turn around some traffic in the intersection.
Since I was about to go up a hill I punched the gas pedal. With the swing-out I
did a near 360 in the intersection, recovered after nearly taking out a fire
hydrant and made a quick exit. Oops, think I need better tires (and need to slow
______________________________ Reply Separator _________________________________
Subject: Re: Re: Roadster gear ratio's
Author: Ronnie Day <firstname.lastname@example.org>
Date: 2/9/2001 2:22 PM
>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.
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.
'71 510 2-dr (Prepared Class Autocrosser)
'73 510 2-dr (Street Toy)