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Old 02-22-2009, 02:02 PM   #36
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Member#: 57989
Join Date: Mar 2004
Chapter/Region: NESIC
Location: Maine
2016 .:R


Originally Posted by MFactory View Post
Multiply the fd ratio by gear ratio, then multiply by the torque = torque at the wheels

Torque is responsible for acceleration. If both had the same torque curve, then the 1st example would be quicker:

3.166 x 4.11 = 13.01 x lbft = torque at the wheels
3.454 x 3.7 = 12.78 x lbft = torque at the wheels
Thanks again! I decided to go with a jdm wrx transmission based on vehicle speed calcs and general information I've read about a shorter final drive, but numbers make things so much clearer for me. Here's the spreadsheet I put together to help make my decision: google doc The 4.44 final drive, even with longer gears, makes a substantial difference in the torque at the wheels for a given engine torque using the formula above. They only downside I see, on my stock powered car, will be cruising rpm. I figure I can just do the speed limit instead of 80 and it will be about even. It'll just take longer to get places.
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