Big Rock 20T pinion in BRCC

[razorrc]

It's normal for sensorless motors that are geared too high (or don't have enough torque). There might be a similar sized motor from a competitor that doesn't cog at 20T but does at 21T, who knows? Every motor from every manufacturer is different, some might cog at 18T, some might cog at 22T, this one cogs at 20T, it is what it is.

This might help:

http://rctruckstop.com/2011/12/15/brushless-motors-sensored-vs-sensorless/

"Sensorless motors simply do not have sensors inside the motor—hence the name sensorless. They determine the likely position of the rotor based on feedback called back-EMF. EMF is short for Electromotive Force. Back-EMF also known as counter-EMF is essentially the resistance or voltage pushing back against the current flowing to the motor.
...
Cogging is a noticeable hesitation at low speeds, often when starting from a stop. Technically, this is the incorrect term and engineers use the word cogging differently, but the point is brushless motors can exhibit a very noticeable stutter at low speeds. Speed control manufacturers that favor sensorless designs go to great lengths with their programming to eliminate any stutter."

If you don't want it to cog, gear it properly or use a more torquey motor, IMO.

 

[bicketybam]

It's normal for sensorless motors that are geared too high (or don't have enough torque). There might be a similar sized motor from a competitor that doesn't cog at 20T but does at 21T, who knows? Every motor from every manufacturer is different, some might cog at 18T, some might cog at 22T, this one cogs at 20T, it is what it is.

This might help:

http://rctruckstop.com/2011/12/15/brushless-motors-sensored-vs-sensorless/

"Sensorless motors simply do not have sensors inside the motor—hence the name sensorless. They determine the likely position of the rotor based on feedback called back-EMF. EMF is short for Electromotive Force. Back-EMF also known as counter-EMF is essentially the resistance or voltage pushing back against the current flowing to the motor.
...
Cogging is a noticeable hesitation at low speeds, often when starting from a stop. Technically, this is the incorrect term and engineers use the word cogging differently, but the point is brushless motors can exhibit a very noticeable stutter at low speeds. Speed control manufacturers that favor sensorless designs go to great lengths with their programming to eliminate any stutter."

If you don't want it to cog, gear it properly or use a more torquey motor, IMO.

It comes with a 15t and they are saying it exhibits cogging with that.

 

[razorrc]

It comes with a 15t and they are saying it exhibits cogging with that.

If they're getting bicketybam type cogging on 15T, then I would say definitely not normal. Sorry I thought you were running 20T in your video, and that cogging looked bad, but it's probably overgeared, so...

 

[jlatimore3]

Does Esc play any role in cogging? Asking cause I got a hobbywing sc8 120 amp Esc that im thinking of swapping out the blx for. I also want to try a 20 tooth so Im wondering an different Esc will make a difference.

 

[TraverseCity420]

I got an MM2 combo but I don't think it would fit in the little body of the brcc

but yeah its cogging on stock.. should not be but... I guess this is what we got to work with...

 

[Jeremy in WI]

I will say, it cogs worse than my granite mega with the hobbywing 3652... It just doesn't seem right now that I'm drunk.

 

[bicketybam]

It’s funny because the Arrma 6s rigs don’t cog at all.

 

[Rynobull]

It’s funny because the Arrma 6s rigs don’t cog at all.

My Talion would cog fairly bad off a stop if I left the 20t pinion on and backflip tires. Stock tires it wouldn't.... but the backflips are a bit bigger, heavier and have more grip.

Now I run a leopard 4282 and max6 and I get no cogging with same gear/tire that used to cause it.

Either gear down, or motor up!

 

[TraverseCity420]

It’s funny because the Arrma 6s rigs don’t cog at all.

THIS!!! I just got back from my notorious run and no coggin tho I did drop back down to 4s still... Barely touch the throttle and BOOM takes off... not the case with the bigrock.. so what gives?


Gearing down from stock on the bigrock seems like a silly idea, And putting in a new motor when everythings brand new seems silly too..

I guess our only option is to suck it up and deal till the internals crap out then replace with something else I guess...


Keeping an eye on this thread tho case anyone comes up with a more logical solution to a stock arrma bigrock cog problem.

 

[Jerry-rigged]

I got an MM2 combo but I don't think it would fit in the little body of the brcc

but yeah its cogging on stock.. should not be but... I guess this is what we got to work with...

I ran a BLX185 ESC in my Granite 4x4, and it is bigger then my MM2, so yeah, it will fit.