# speaking of gear ratio



## major (Apr 4, 2008)

patallen said:


> Hi, i am making a project for my son, its a 1.25 scale willys with a mars motor.
> i plan to run the motor at 24 or 36v, with a home made driver that i am building.
> 
> I was wondering what ratio i should use, i know how to calculate the speed versus voltage/amp versus tire diameter,...
> ...


I can't give you a number without knowing a lot more about the project, but I can give some advice. Forget about the transmission and go with a simple reducer. A chain or belt works well on kart size vehicles. Give the ratio your best calculated shot, but leave plenty of room for adjustment in sprocket/pulley size and center distance.


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## Yabert (Feb 7, 2010)

Hi

You can roughly calculate acceleration on flat terrain with F=ma 
In your case, F = motor peak torque x ratio / wheel radius.
Example: F = 20 Nm x 2 / 0.133m = 300 N


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