View Full Version : Gear ratio: speed calculator

21-09-01, 07:40 PM
I am putting a new transmission in my car this winter and wanted to see what the effect of different gear ratios would be on the cars speed. I constructed the attached Excel file based on stuff I gleaned from a US hot rod website.

Basically you put in the rolloing diameter of your rear wheels, the axle ratio and the the ratios of the box (up to six speeds) and the spreadsheet will do the rest calculating mph in increments of 1000 rpm up to 5500.

Hope this helps others trying to figure out the best ratios in a manual box.