On my manual 06 Roadster the 5th gear has the 1:1 ratio. How do you figure your ratio if you change the rear end or does it stay the same? If there is a formula? I will gladly do the work just need a point in the right direction. Thanks for any upcoming explanations.

 

Transmission gears are absolute. You are NOT changing any transmission gearing with rear gearing change. You are, however, changing gear multiplication with lower/higher rear gearing.

 

1:1 means that the engine crank and the prop shaft are spinning at the same rpm. Changing the final drive has no effect on this. It will affect the ratio between rear wheel and prop shaft speeds.

 

Thanks that is what I thought but was told otherwise. Appreciate the confirmation.