380 sized brushless motors

[fredswain]

I'm pretty new to the world of brushless motors but have tons of experience with brushed motors. My lone brushless has gobs of power. Tons of it. Then again at an 8.5T I probably started out with one that is a bit much. It is in a XXX though and has what I feel is too much power for my RC10's and JRX's. I am building a recreation of my childhood 6 gear complete with smaller wheels, and short arms. That car always had 27 turn brushed stock motors and while a 17.5T brushless may be fairly close to it, I feel the brushless still has too much torque. The idea is to run a 380 sized brushless instead. It should have lower torque but still be capable of more than enough power depending on which one is used. Has anyone tried a 380 sized brushless? How did it drive?

[THEYTOOKMYTHUMB]

Sorry, but I see no reason to use a 380 size brushless in anything except maybe a "what's old is new" Grasshopper. Maybe I'm misunderstanding what you are trying to do though.

[fredswain]

I'm trying to keep the motor torque level down to something closer to what the brushed motors had. Brushless motors just have so much more torque. I'm trying to find a way to get a similar power band to a brushed motor but with a brushless. Thinking more about it, perhaps I can simulate the effect by just turning down the punch on the esc.

[Coelacanth]

Sorry, but I see no reason to use a 380 size brushless in anything except maybe a "what's old is new" Grasshopper. Maybe I'm misunderstanding what you are trying to do though.

Actually, a lot of the cheaper brushless motors out there are 380-sized motors that are placed in 540-sized cans. I think many of the EZRun motors are like this. It's not a bad thing because they put out so much power and RPM, no matter how big the can is; but the 540-sized ones are usually more expensive, will run cooler, and have more torque & RPM.

You can usually tell the difference by looking at the can; if it's smooth, it's most likely a bigger 540-sized motor; if it has what looks like heatsink grooves, it's a 380-size.

Here's the 540-size motor I chose for Barney:
http://www.hobbypartz.com/96m25-car-3650-3200.html

And here's a 380-size motor:
http://www.hobbypartz.com/96m270-2838-3900kv-17t.html

The outer motor diameter is the same; either motor will fit where a 540-sized motor would fit, but the guts inside the 380 are smaller, more prone to overheating, and a bit weaker power, all else being equal.

More examples: Here's a very common 10T EZRun motor that's actually 380-sized inside a 540-sized can. Lots of the guys here and elsewhere are probably running these motors with no problems.
http://www.ebay.ca/itm/EZrun-Series-10T-Sensorless-Brushless-Motor-3900KV-1-10-/140362418516?pt=Radio_Control_Parts_Accessories&hash=item20ae408954

And here's the 540-sized equivalent; notice the difference in price & specs:
http://www.ebay.ca/itm/eZRun-3655-10T-RC-Brushless-Motor-1-10-2WD-SCT-Car-/260961964346?pt=Radio_Control_Parts_Accessories&hash=item3cc28b913a

[kaiser]

you may want to try a 21.5t 540 sized motor. the 380 ezruns are actually pretty fast. the 13t and 9t both turn some serious rpms for little motors.
the 9t is a little beast.

[fredswain]

I've got a 21.5T in an F1 car so I guess I do have more than 1 brushless. I just consider off road my home! I could try it in the RC10 but I think it's going to be a little slower than I'd like. I don't need it to be as fast as the 8.5T in my mid motor XXX. That car can do acceleration back flips at 30 mph! I've got a brushed Trinity P2K2 stock motor which is a beast of a stock motor. We gps clocked it at a top speed of 27 mph which is quite quick for a 27 turn brushed motor but it's average powerband was much lower than the brushless motors I've driven. You definitely need driving technique and momentum to pull you through corners. I do want a sensored motor though so that may eliminate the idea of a 380 sized can. Perhaps the 17.5T with the boost dialed down a bit would be a fairly good match. I also don't want too much motor for a car with no slipper.

[THEYTOOKMYTHUMB]

Hmm, here is some more info that may help you. There's a lot more going on out in the world than I thought. Always learning in this hobby I guess.

http://www.rc10talk.com/viewtopic.php?f=33&t=25728

[CamplinP]

I would suggest getting a motor with as much power as you think you would possibly use and then dial it down from there to suit you needs. I am not familiar with the EZ run products but I have Castle 5700kv motors on all my stuff and through my laptop programming I can make them run however I wish.

[Mr. ED]

Tamiya released the mr-01 chassis with a 380 moter and adapter.

[Coelacanth]

Tamiya released the mr-01 chassis with a 380 moter and adapter.

That's pretty much what all those EZRun motors are; 380's in a 540-sized can. They put out more than enough power to run 1/10 offroad buggies and can be tweaked with the programmer cards (if buying an EZrun motor/ESC combo) to adjust punch (off the line torque).

[fredswain]

The 21.5T in my F1 car and the 8.5T in my XXX are both sensored. I've only driven 2 sensorless motors and they both cogged on the low end. Enough so that I found it annoying. I've heard that this is a current issue and that turning down the punch settings or running higher C batteries can help this. Does anyone know? I'm leaning towards just going with a 17.5T sensored right now since I don't think there is a 380 size that is sensored. I don't know for sure though.

[Coelacanth]

The 21.5T in my F1 car and the 8.5T in my XXX are both sensored. I've only driven 2 sensorless motors and they both cogged on the low end. Enough so that I found it annoying. I've heard that this is a current issue and that turning down the punch settings or running higher C batteries can help this. Does anyone know? I'm leaning towards just going with a 17.5T sensored right now since I don't think there is a 380 size that is sensored. I don't know for sure though.

Fred, cogging shouldn't be a problem associated with all sensorless motors, even though that's what you have experienced. The vast majority of people with EZRun sensorless setups have no issues. When I was looking into those, I went through dozens and dozens of pages of comments on RCTech.net and the number of problems was tiny--and that was due to something wrong with the setup or the person not reading the manual.

Maybe this topic might help you with diagnosing your cogging problems, but the problem is *not* the fault of the motor being sensorless.

http://www.rctech.net/forum/electric-off-road/508740-ezrun-35-cogging-problems.html

[kaiser]

i never had any cogging with my ezruns, both the 9t 380 and the 8.5t 540.

[Mr. ED]

Tamiya seems to agree with JK.

This is the adapter plate they use on the rm-01 sporting a brushed 380.
Note that the moter does not go centered: unlike the 540 sized 380 brushless moters. I guess this is to allow a proper ratio adjustment for the differences between 380 and 540?
I 've found a new axle for my old plazma and am seriously considering tuning it down with a 380 and maybe even single cell lipo or a 1/16th pack. Any considerations?
Also: any ideas on where to get the sleeve to thicken the 380 moter axle for the standard 540 pinions?

[THEYTOOKMYTHUMB]

Also: any ideas on where to get the sleeve to thicken the 380 moter axle for the standard 540 pinions?

You could probably get away with using a small brass sleeve. Either drill a hole for the set screw to go through or just use the set screw to crimp the tubing on to the shaft. A pilot hole would be the better solution I think.