Losi Rock Rey Thread
#46
Tech Champion
iTrader: (1)
The cogging isn't the motor's fault, it's the ESC's fault. I'm running the stock motor with a SkyRC Toro SC120 sensorless ESC and I get almost no cogging, even when I drive it below 1mph. SkyRC programs their ESCs to run the motor differently at very low speeds (sorry I can't provide more detail, all I know is you can hear a distinct change in the noise the motor makes when it revs-up past ~250rpm), and whatever it is they do causes sensorless motors to run very smoothly on startup. Since SkyRC and HobbyWing are both based in China, which has no intellectual-property laws to speak of, I really wish HobbyWing would copy whatever it is SkyRC does, because all RCers deserve to benefit from it.
#47
Tech Initiate
Yep, it's a controls problem wherein an ESC running in sensorless mode doesn't immediately know which direction a motor is spinning. The motor needs to start spinning so that the ESC can read the back EMF. Digikey has a pretty quick read on this that explains the process in more detail, if you are interested.
https://www.digikey.com/en/articles/...s-via-back-emf
The hall effect transducers on the sensored motors tell the ESC the precise location and direction of the motor rotation, even at speeds down to zero. Interesting to see that HW/SkyRC have significantly improved cogging on sensorless systems in your experience. I will definitely have to give these a try as I've yet to see any sensorless system drive a crawler slowly up a grade or hold it on a hill without cogging and/or creating a lot of heat in the process. Thanks for the info.
https://www.digikey.com/en/articles/...s-via-back-emf
The hall effect transducers on the sensored motors tell the ESC the precise location and direction of the motor rotation, even at speeds down to zero. Interesting to see that HW/SkyRC have significantly improved cogging on sensorless systems in your experience. I will definitely have to give these a try as I've yet to see any sensorless system drive a crawler slowly up a grade or hold it on a hill without cogging and/or creating a lot of heat in the process. Thanks for the info.
#48
Tech Elite
iTrader: (7)
I'm thinking about pulling the trigger on one of these. Is there still a problem with the stock plastic servo saver? What about battery wire orientation? I have a hard case battery where the wires come out of the top corner and I want to know if this orientation will work.
#49
Tech Champion
iTrader: (1)
The hall effect transducers on the sensored motors tell the ESC the precise location and direction of the motor rotation, even at speeds down to zero. Interesting to see that HW/SkyRC have significantly improved cogging on sensorless systems in your experience. I will definitely have to give these a try as I've yet to see any sensorless system drive a crawler slowly up a grade or hold it on a hill without cogging and/or creating a lot of heat in the process. Thanks for the info.
#50
Tech Champion
iTrader: (1)
I'm thinking about pulling the trigger on one of these. Is there still a problem with the stock plastic servo saver? What about battery wire orientation? I have a hard case battery where the wires come out of the top corner and I want to know if this orientation will work.
Last edited by fyrstormer; 03-29-2018 at 04:04 PM.
#52
Tech Initiate
I'm thinking about pulling the trigger on one of these. Is there still a problem with the stock plastic servo saver? What about battery wire orientation? I have a hard case battery where the wires come out of the top corner and I want to know if this orientation will work.
The sloth-like servo will have you overshooting corners at speed and it's anemic power will lock up just looking at a rock. You shouldn't have a problem with the plastic horn and servo saver if you don't upgrade the servo and keep it away from curbs and the like. I did upgrade my servo and used Losi's aluminum horn (TLR1557), but then quickly found the next weak link - the servo saver itself. I caught a curb at speed and popped the ball stud out of the plastic link. It didn't break per se and could probably be used as is, but I don't want to have to keep screwing the ball stud back in all of the time.
Last night, I installed Losi's aluminum servo saver set (LOS331002). It's a little pricey at $35, but well worth it for my application. I can tighten up the servo saver, increasing steering authority and feel, without having to worry about problems with the linkages breaking or ball studs pulling out. I don't have the greatest servo, so I'll probably end up stripping some gears or breaking a ball stud (could go Ti), but that's a price I'm willing to pay for better control at speed and more torque when bound up in the rocks.
#53
Tech Initiate
MOTOR MOUNTING
Just a heads up to check for clearance between your motor can and the chassis. I'm on the correct mounting holes for my new pinion, but the extra diameter from the cooling fins on my Tekin T8 has it hitting the chassis. Going to relieve the cover a bit with my Dremel.
Just a heads up to check for clearance between your motor can and the chassis. I'm on the correct mounting holes for my new pinion, but the extra diameter from the cooling fins on my Tekin T8 has it hitting the chassis. Going to relieve the cover a bit with my Dremel.
#54
Tech Prophet
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Join Date: Nov 2014
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#55
Any suggestions on shock caps? Preferably aluminum.
#57
Well, I broke the front camber link mount on my rock rey today. Contacted customer service because the site said it was unavailable until August. I was informed that what the site says is accurate and there was nothing they could do to help. As much as I love this car, I have had horrible luck since day one. Stripped servo horn, motor fried, tires came unglued, broken shock cap, esc fried, and now I cant even get a replacememt camber link mount until August. New car and I can't use it again for 5 months.
Last edited by Kathy08; 04-09-2017 at 03:44 PM.
#58
*Rock Rey 6061 Billet Aluminum Front Camber Link Mount*
As many of you might have read in my post above, I broke my front camber link mount yesterday. Unfortunately the part is not due to release from Losi for 5 months. After speaking with one of our engineers, he is interested in milling a batch of these out of 6061 billet aluminum if there is interest. Tell me, would you buy one if they were available and what would you be willing to pay.
As many of you might have read in my post above, I broke my front camber link mount yesterday. Unfortunately the part is not due to release from Losi for 5 months. After speaking with one of our engineers, he is interested in milling a batch of these out of 6061 billet aluminum if there is interest. Tell me, would you buy one if they were available and what would you be willing to pay.
#59
Tech Elite
iTrader: (7)
*Rock Rey 6061 Billet Aluminum Front Camber Link Mount*
As many of you might have read in my post above, I broke my front camber link mount yesterday. Unfortunately the part is not due to release from Losi for 5 months. After speaking with one of our engineers, he is interested in milling a batch of these out of 6061 billet aluminum if there is interest. Tell me, would you buy one if they were available and what would you be willing to pay.
As many of you might have read in my post above, I broke my front camber link mount yesterday. Unfortunately the part is not due to release from Losi for 5 months. After speaking with one of our engineers, he is interested in milling a batch of these out of 6061 billet aluminum if there is interest. Tell me, would you buy one if they were available and what would you be willing to pay.
#60