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Discussions Question and Answer Forums Razor Electric Scooter, Bike, and Go Kart Modification Forum

What motor and speed control combination provides the most torque?

My 5 yr old son races power wheels in a modified class. This year we upgraded to a custom steel frame and razor scooter motor. It's a little slow out of the gate, but the top speed is adequate. The problems are at the start and in the turns. With a solid axle rear end, the motor has a hard time pushing two mini-tractor tires through positive traction. We also lose a considerable amount of power going up hills. I am looking for as much torque as possible and a top speed of at least 10mph. Variable speed is not necessary, a wheelie bar can be installed if needed.
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Also,.. races last less than 30 seconds. They include obstacles like hills, sand, and mud. Batteries can be changed out in between races. So batteries don't need to last long.
The higher the Watts rating that the motor has the more power and torque it will have. I can not see the motor in the photos very well however from what I can see it looks like a 24 Volt Currie motor and controller which could be rated anywhere between 400 or 750 Watts. However this Currie motor has a small and unventilated case so it is not going to have the same amount of torque as a motor with the same ratings that has a large ventilated case.

You could upgrade to a 24 Volt 500 Watt motor with a large case such as our MOT-24500X2500B and this motor might provide the torque that you are looking for or it might fall a little short on torque due to the positive traction rear end since that eats up a tremendous amount of power in the corners.


Or you could upgrade to a 36 Volt 1000 Watt motor such as our MOT-361000B. This motor would provide a lot more power and torque that the currently installed motor has.


A power contactor such as our RLY-24150 or RLY-36150 could be substituted for a variable speed controller and it would provide unlimited current to pass from the battery pack to the motor as opposed to a speed controller which would limit the amount of current. However electric scooter motors are designed to be used with speed controllers and using them with a power contactor could possibly over stress the motor's shaft and sprocket and cause them to break or strip due to the instantaneous acceleration that a power contactor would provide. 


As far as top speed goes any of our larger 500 through 1000 Watt motors would have the same or higher RPM than the currently installed motor has so the top speed would be the same or higher than it is now. The current motor may be lugging due to a higher than necessary gear ratio though so a more powerful motor may provide a faster top speed due to this. We have a top speed and gear ratio calculator that can be used to determine the top speed of the Power Wheels racer with any motor that is installed in it.


Using the right gear ratio for the job is one of the most important things when fast acceleration and hi torque are required. For instance if a motor was geared for a 20 MPH top speed then it would accelerate much slower than if it was geared for a 10 MPH top speed. We can help with running gear ratio and top speed calculations if you would like.


Please let us know if you have any questions.

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