Originally posted by gearless
You can't, because you have two variables - spur and pinion.
You must choose the teeth of one of them and then calculate the other.
So, what if I choose to use 93 pinion, then I should go for 37 spur? (93/37*2.4375) = 6.1
or I keep 124 pinion, then I go for 49 spur (124/49*2.4375) = 6.1 too