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Razor Groundforce Drifter Double speed

 I built a Razor GFD with a 24v 750w motor for my son. It was a little faster and had lots of torque.


I want to build a Razor GFD that will go double the speed. I'm willing to replace motor, controller and thumb throttle. I would prefer a 24v solution vs. 36v and adding a third battery mostly due to space constraints on the Drifter.  However, if a 36v is far superior I'm sure I can figure out how to package it.


What's the best and simplest solution to double speed.

The Ground Force Drifter's original motor is only 250 Watts so a 750 watt motor should be plenty powerful enough to double its speed.


To double the speed and keep the battery pack at 24 Volts the gear ratio would need to be increased. This could be done by installing a motor sprocket with twice as many teeth than are on it now, or by installing an axle sprocket with half as many teeth than are on it now. I ran some gear ratio calculations to show the increase in speed with these different sprocket configurations.

Unfortunately we can not get 22 teeth motor sprockets or 16 teeth Ground Force Drifter Axle sprockets. However we do carry a 16 tooth sprocket for #25 chain with a 1/2" bore that could be drilled or machined out to have the same size inner diameter as original 32 tooth Ground Force Drifter sprocket. If I remember correctly the Drifter's original axle sprocket has a 17mm ID bore but I might be wrong so please measure it before drilling out a new sprocket to replace it.

  SPR-2516B

This 16 tooth sprocket is our item # SPR-2516B which is available on this page: http://www.electricscooterparts.com/sprockets25chain-motor.html


If the battery pack was increased from 24 Volts to 36 Volts the top speed would not be doubled and would only be around 19 or 20 MPH according to my calculations. Running a 24 volt motor on 36 Volts would also be more risky than running it on 24 Volts because it would run hotter and have a better chance of burning out. Here are my calculations for running the motor on 36 Volts.

I based all of these calculation on a 2500 RPM motor. If your motor has a higher or lower RPM then the calculations would need to be slightly adjusted for the difference in RPM.


Here are links to the calculators I used.

Top Speed Gear Ratio Calculator: http://www.electricscooterparts.com/motorwheelgearratio.html

Motor Overvoltage RPM Calculator: http://www.electricscooterparts.com/motor-overvoltage-rpm-calculator.html


I think that installing a custom bored 16 tooth sprocket on the rear axle would be the best and simplest solution to double the speed.


Please let me know if you have any questions.

I'm sure I can bore the 16 tooth sprocket. Would the Drifter still have good acceleration and torque?

What motor, controller, thumb throttle should I order?

 

With the 32 tooth axle sprocket replaced by a 16 tooth axle sprocket the acceleration and torque would be significantly reduced at least by 50%. If you do not need a 25 MPH top speed and still want good acceleration an torque then maybe a less drastic gear ratio change would be better, such as changing to a 20 or 24 tooth axle sprocket instead of a 16 tooth.


Regarding the motor, controller and throttle question how many Volts and Watts do you want to increase the power to?

As far as Volts and Watts I don't have a limit. Sometimes it's more about quality and efficiency. With that said 750w/controller combo that delivers really good power and efficiency. If there is a motor with higher or lower voltage that deliver better performance that works too. I'm also not opposed to a 36v motor with a 36v controller if the performance is significantly better.

 

With 24 Volt motors the highest power available for a motor with a mounting base is 500 Watts. There are 24 Volt 750 Watt motors available without a mounting base. These 24 Volt 750 Watt motors are smaller in size than the 24 Volt 500 Watt motors with mounting base so they do not have quite the same cooling ability as the larger motors.

36 Volt motors with mounting bases are available up to 1000 Watts. If you are looking for maximum power and speed then a 36 Volt system would be the best choice.

A 36 Volt 1000 Watt motor such as our item # MOT-361000B would offer the best power and it is a large motor with good cooling ability. This motor's dimensions are 4-1/4" wide x 6" long excluding shaft, and 7" long including shaft.

For a 36 Volt 1000 Watt controller our item # SPD-CT660B9 is a perfect match for a 36 Volt 1000 Watt motor.

As far as thumb throttles go we have them available with no power meter, with a power meter, and also with a power meter and switch that could be used to turn the drifter kart on and off. All of these throttles work with the CT660B9 controller so the choice would be yours as to which one to use.


Please let me know if you have any questions.
The 36v Currie Motor MOT-SD361000 is smaller and lighter. It's only 4.5" deep with 3 batteries it should be under 12.25" fitting under the cover for the drifter. I should be able to mount the controller on top of the rear enclosure. What controller and thumb throttle combo works with this motor? Also what 20 or 24 tooth rear gears work for the drifter?

 

The MOT-SD361000 is a great motor, it is made with extremely powerful neodymium magnets which make it very compact and powerful. The same controller and throttles that I previously mentioned for use with the MOT-361000B will work perfectly with the MOT-SD361000.

The 20 and 24 tooth sprockets I was referring to are item # SPR-2520 and SPR-2524 which are available on this page: http://www.electricscooterparts.com/sprockets25chain-motor.html

Please let me know if you have any questions.
One last thing. Since I'm changing over to 36v do I need to change the charger port, fuses, on/off switch or anything else?

 

When changing the Ground Force Drifter over to a 36 Volt 1000 Watt electrical system the original charger port and power switch can be reused. To be able to handle the extra amount of power that the 1000 Watt motor will draw all of the wiring between the batteries and controller should be upgraded to 12 gauge wire, and the fuse changed to 40 Amps. The original wiring should be 14 gauge. That is all I can think of that would need to be changed with the electrical system.

 

If you have any further questions please let me know.

Does the thumb throttle THR-38 work with 36v controller SPD-361000. Just plug and play? Also will the Razor GFD brake connector plug into the 36v controller SPD-361000 Mating Connector
Item # CNX-51

 

Yes the THR-38 thumb throttle woks with the SPD-361000 controller. THR-38 comes with a 3 wire connector that plugs right into the SPD-361000 controller so it is plug and play. The THR-38 throttle's wire terminals would just need to be pushed into the included connector before it is plugged into the controller.


The Ground Force Drifter's brake lever switch has a 2 wire male connector, and the SPD-361000 has a 2 wire male connector, so they are not plug and play. The brake lever switch's male connector would need to be changed over to a female connector in order for it to plug into the controller. We could also make an adapter that would allow the GFD brake connector to plug into the SPD-361000 controller brake connector for $3.95 if you do not want to put a different connector on the brake lever.


The SPD-361000 has the best cooling of our 1000 watt 36 Volt controllers because it is the largest one available. However it does require a heavy duty switch such as our SWT-156 or SWT-700, or a power contactor such as our RLY-36150 to turn it on and off. The SPD-CT660B9 could be turned on and off with the Ground Force Drifter's original power switch.


If you have any further questions please do not hesitate to ask.

Are you kidding? $3.95 for plug and play... awe yeah ;-) I'm in. How do I order it.

 

I ordered everything and will post a photo when it's done.

 


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