hello i have a 1970 mustang, has a c4 ,just put 3.70 gears in it,tire height is 24.5 inches,can anyone tell me what gear i need for the speedometer,the c4 is out of a 1968 mustang,any help would be appreciated
21 tooth gear will do you. To ge the driven gear tooth count, multiply the drive gear tooth count (7 for all C-4's) x axle ratio (3.70) x tire revolutions per mile (24.5 x 3.1416 ( Pi ) =76.97). Divide 76.97 into 63,360 (inches per mile) to get revolutions per mile. Once you multiply these three figures, divide the result by 1000 to get the tooth count for the driven gear.
hello , i had a 21 tooth gear in there ,it didnt seem right,unless the car is that fast, i just put a 23 tooth in but didnt try it yet,thankyou for the information