Is it better to use the speed 393 with a gear ratio for torque or a torque 393 with gear ratios for speed?
It depends on what you are using the motor(s) for. What would you use the 393 motor(s) for?
I was hoping I’d be able to use one to drive a 3 wheel drivetrain.
EDIT: They will be the 2.75" double omni wheels.
we have had good success with 393 geared for speed with a 1:1 and 4" wheels.
Well using a 393 geared for speed internally, then externally gearing it for torque is not logical. Your are basically gearing it up, then down. The 393 running at 100 rpm makes more sense though. Except dont go over 160 rpm because then it would be pointless in doing so because you could just internally gear it for speed. So if you want torque dont use the speed configuration, and if you want speed, you can use the torque configuration, just remember not to go over 160 rpm. Hope this helps, you should check out the vex speed chart to see what configuration works best for you.
https://vexforum.com/gallery/showimage.php?i=72&c=4