Easy answer; No you can't change the kv of your motor without changing the motor itself. Get a smaller pinion or a different motor.

Not sure the following question has been answered

Does Castle's "Torque Limit" function work differently than simply lowering the throttle EPA ?

Guess we can ask them ..............

Cheers

Crusey, could you contact Castle?
On the rc-monster forum Patrick has said that torque control is not a direct current limiter, but controls torque directly, and in another post that they're working towards traction control, so I guess it is based on measuring phase delay of the motor.

I dont use it but will ask the question on rc monster

Guess the better question is do all of the following have the same effect

Limiting throttle travel (EPA)
Torque Limiting
Limiting Forward Power

Cheers

Yes - the means of accomplishing these is the same (delivering less voltage - and thus less current - to the motor winding).

That statement makes absolutely no sense. In an "ideal" electric motor, torque is directly proportional to current, and so controlling output torque is accomplished by controlling the winding current. There are a lot of other variables that factor into this, but that's the general concept.

Uh, what? Please explain what you mean by "measuring phase delay", because that is not a term I've heard in several years of designing BLDC motors and controllers.

The most likely way to implement traction control would be to limit the rate at which the motor is allowed to accelerate. This would be rather simple to implement in software, but the calibration of it for a given setup (motor/voltage/gearing/tire size) would be pretty tricky for the average hobbyist.

Look up Patrick's comments in this thread, especially post #38.

I mean measuring how far off the motor is from its ideal no-load position the more the difference, the higher torque it is forced on. Since the motor is sensorless, I think it can be determined by comparing phase of the the control signal and the back emf. I accept that phase delay is not the correct technical term for it, but it was my "best estimate". What would be the right phrase?

I agree that it takes a lot of parameters to set up right, especially without an accelerometer.

Had a quick scan of that thread, makes my head hurt even more

Torque Limit will not effect top speed ?

So it appears it does not have the same effect as limiting EPA or forward power

Cheers

Didn't think this would be so controversial.
I ordered some spur gears and some pinion gears and I'm going to play around with the ratios.
Thank you so much to all of you for so much information that my brain is still comprehending.

Thanks - that makes a lot of sense. Basically, what is being discussed here is a "feed-forward" control scheme, where a model of the motor is used to determine the required modulation index (PWM duty cycle) to achieve the desired current (which then in turn controls the amount of shaft torque). This is often much easier to implement than a feedback system, where to the winding current is measured by the controller (seems simple in concept, but is rather difficult in practice).

Note that the end result is the same - the winding current is limited in order to limit torque.

The problem with this is that any proper control algorithm (sensored or sensorless) should not allow the rotor to "lag" as more torque is applied.