Brushless unsensored motors low speed problems

[Mr. Crawley EC]

I have a 1800kv Holmes Hobbies revolver and a 1750 3 brothers yellow jacket sensorless brushed motors, both connected to a castle mamba x and a sidewinder 4. When I get to very low speed in Rock crawling (just when you need smoothness land lowest speed), I get this tremble, like they hesitate back and forward, which really mess up everything and makes me loose control.
Is it a configuration problem?
Or I just need to get brushless sensored or brushed motors?
Thanks for your help.

 

[mewalsh100]

I have a 1800kv Holmes Hobbies revolver and a 1750 3 brothers yellow jacket sensorless brushed motors, both connected to a castle mamba x and a sidewinder 4. When I get to very low speed in Rock crawling (just when you need smoothness land lowest speed), I get this tremble, like they hesitate back and forward, which really mess up everything and makes me loose control.
Is it a configuration problem?
Or I just need to get brushless sensored or brushed motors?
Thanks for your help.

Both are outrunners and should be fine sensorless. I've got the HH 1800kv Revolver paired with a Mamba-X on my TRX and it's low speed control, start-up and feel are phenomenal. It will creep at a nearly undetectable speed. I'd pull your ESC's up in CastleLink and check all your settings. There's a Holmes Hobbies video posted here somewhere that runs through ideal, baseline settings. What is your Spur gear tooth count? Pinion Count? Final drive ratio? What packs / voltage are you running?

 

[TheLetterJ]

What's your gearing? I can barely tell a difference between my Revolver and my Puller Pro on startup (both run from Mamba X's with the same throttle curves), but the car with the Revolver is geared 65:1 and is run on 4s to get some wheel speed out of it. The brushed Crawlmaster is smoother for sure, but both sensored and non-sensored outrunner with low gearing are both on par with at least a cheap brushed motor for startup... with way more power. If you don't want/need brushless power, there's nothing wrong with going brushed, but I'd try gearing down before switching back.

 

[Mr. Crawley EC]

88t spour, 21t motor pinion, 48t. Runing on 3S. Tuned the ESC according to John Holmes video. I’m sure I’m doing something wrong since inn new to the gear relation .

 

[TheLetterJ]

That's pretty tall gearing, of course without knowing the rest of your drivetrain (transmission and axles) it's hard to say. Try dropping down on the pinion to something like 14 or 15 and see how that goes. Should make it about 30% smoother... and slower. If it's smooth enough then, but you now find it too slow, bump up to 4s (at least on the car with a Mamba X) to get more rpm out of it.

 

[mewalsh100]

Yeah, 88 - 21 is way too tall. Drop that pinion to a 15t and that gets you in about 5.8 : 1.