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Hot motor and gearing ? so lost

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Old 05-25-2018, 12:03 AM
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richberstler
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Default Hot motor and gearing ? so lost

It seems to me the motor will run at it's expected RPM/T. I have a 9T brushless motor at the moment in my ECX Torment 4WD, brushless. I can't seem to understand how gearing will affect how the motor will spin. Under geard or over geared. If anything over geared seems like the worst thing ever, but hot motor and cool ESC/battery is my confusion. (If it matters just got 40C 2S batteries, ESC handles On-Road≥5.5T, Off-Road≥8.5T)

My point is the batt/esc is driving the motor to run. The motor should run at whatever RPM it's supposed to. The gears seem to me to only determine speed/torque differences, to me. If I lower the tooth count it only seems I am putting more stress on the motor. I don't get how that makes it run cooler.

Can someone REALLY dumb it down for me to the basics so I can understand the math?
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Old 05-29-2018, 03:13 AM
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RustyUs
 
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"Gearing down" (using smaller pinion gear, and/or using larger spur gear) will normally make your motor run cooler. It will be easier for your motor to make a revolution. Just think of yourself riding a bike. The pedal gears are like a RC car's pinion gears, and the gears on a bike's rear wheel are like a RC car's spur gear.

If you’re going uphill and it’s too difficult, shift down.
If your legs are spinning the pedals way too fast (it’s too “easy”) then shift up.

To determine if you motor is being stressed too much, invest in an infrared thermometer. Some people using their fingers to test temps are not as accurate as you might think.
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Old 05-29-2018, 11:23 AM
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9t in a 4x4 sct is way to high kv.. understanding gears will not help..still will run hot id run a smaller kv then you can try and understand gearing.. lower is slower but can make things hotter
larger is faster
smaller gear will give you faster acceleration
bigger gear will give you more topend
theres a happy medium..depends on terrain and driving style.how hard you pull trigger.i dont need 50 mph in a 4x4 offroad. unless im running onroad
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Old 05-29-2018, 02:34 PM
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What 9T brushless motor are we talking about? I hope it's not one of them "finned out" 380 sized motors.



Those motors are better suited for lightweight 2wd RCs.

The brushed version of the Torment comes with a 550 sized 15T motor. I don't know what pinion gear you are using at the moment, but you should always gear down when switching to a motor with more rpms to take it easier on the motor.

If it were me, i'd probably throw a good 550/3656 sized motor in a short course truck like the Torment. Somewhere in the 3800kv range. Heck, who am I kiddin', I'd be using a 3000~3300kv motor. For a loose super rough off-road track, 25~30 MPH is fast enough for me.
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