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Razor Ground Force Gear Ratio and motor shaft


I built a kart based on a Kettler pedal car. I am thinking of switching my motor to the Razor Ground Force. Can someone tell me:

a)What is the stock gear ratio on a Razor Ground Force?

b)What is the shaft diameter?

I would probably try to mount one of my metric sprockets on the Razor motor, since i can't chance the sprocket on the drive shaft. 



ps - photo attached. Body almost done Bondo-ing.

The Razor Ground Force rear axle shaft diameter is 20mm. It has a 3.09:1 gear ratio and a top speed of 12 miles per hour.

The Ground Force's gear ratio is suitable for a vehicle with a 250 Watt 2500 RPM motor and 5 inch diameter tires. It looks like the tires on your kart are larger than 5 inches though so a lower gear ratio might be needed for it.

If you are going to use a 250 Watt motor then as long as the kart will be driven on primarily flat surfaces 12 mph is a good top speed to aim for when making a gear ratio calculation. We have a gear ratio calculator designed for small electric vehicles with chain drive at this link: http://www.electricscooterparts.com/motorwheelgearratio.html

By the way we like the body you are building. It looks like crossover between a Firebird Trans Am, Porsche 918 Spyder, and Formula One race car.

Please let us know if you have any question.

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