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Old 2012.08.15, 02:46 AM   #10
Felix2010
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Join Date: Dec 2006
Location: Southern NH
Posts: 987
For AWD: Running lower than 5.0:1 gear ratio (such as 4.5:1) with a 35t motor with Neo magnets (T2+ or CHILI) if you run hard (Hard acceleration/deceleration and starts/stops) you will definitely cause a lot of heat to be generated by the FET's. The FETs will keep pumping out the Amps until failure or to the point of chassis melting and FET damage or even FET solder softening to where the solder melts and re-freezes on the board >>where you get things like side-ways FETS on blown boards and missing FETs that actually melted right-off the PCB...

I guess a better way to put it is, unless you're racing on a HUGE track, then 5.0:1 gear ratios or lower will most-likely cost you performance. The one case for low-ratio gearing with fast RPM motors is when you can actually use the extra HP produced (HUGE track).

For 2WD: You can definitely run lower than 5.0:1 (Like 4.5:1) gear ratio's using a similar 35t/NEO-mag motor. Less resistance in the 2WD drivetrain, and lighter. Just don't go to high of pinion (BIG pinion) like 14/53 or 12/52 or else you'll heat the FETs fast; If you have a lot of grip on your track too, this friction causes more current flow due to higher % power-demand on-power and thus produces PCB/solder/MOSFET failure & chassis distortion/melting.
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