You want the speedometer cable to turn 1001 rev per mile. Measure rolling circumference by making a chalk mark on the tire & floor, roll vehicle forward untill mark on tire again lined up w/ floor, make second mark on floor & measure the distance between the 2. Now for the math: 63,360" in a mile, devide by tire rolling circumference = tire rev / mile. Devide this by the axle ratio and you know propshaft rev / mile. The ratio between the drive gear(on the transmission output shaft) & driven gear(mates to speedo cable) will equal the ratio from propshaft rev / mile & 1001 (speedo cable rev / mile).
Last edited by BC59; 02/20/2013 2:54 PM.
