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 To: "Roadster List" , Re[4]: Roadster gear ratio's Fred_Katz@ci.sf.ca.us Fri, 9 Feb 2001 13:37:18 -0800
 ```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 down). Fred ______________________________ Reply Separator _________________________________ Subject: Re: Re[2]: Roadster gear ratio's Author: Ronnie Day 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. 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? 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 ) 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) ```