SMT 10 brushless motor heat

[jakehoek]

I recently upgraded my axial SMT 10 gravedigger from brushed to brushless and am experiencing more motor heat than expected. I went with a hobbywing sensored combo with a 3300kv motor and 80a esc. I kept the stock gearing of a 14t pinion as I didn’t want much speed out of this truck, mainly more torque and run time on my 2s lipo battery. I’m thinking i might need a bigger pinion as this truck tops out quite fast and is definitely undergeared. and i find my self running it wide open 24/7. Would this help my motor heat? I’m thinking so but wanted to ask the community and see if anyone had experience with undergeared brushless motors getting hot.

 

[Tunedfrog]

A smaller pinion will help with heat but a slower ride. Larger pinion will make it faster and create even more heat.

 

[jakehoek]

That’s what I always thought too, but I feel like this truck is already way undergeared. And that the motor running at WOT all the time without adequate cooling, because it is going slower, thus less air is running past the motor to cool it. Idk just a theory, wondering if anyone else had experience with this.

 

[Tunedfrog]

Your best bet is to purchase a thermo gun and watch the heat.
Sometimes you need to sacrifice one to get the other.
Do you have a heat sink and fan on it?

 

[jakehoek]

Your best bet is to purchase a thermo gun and watch the heat.
Sometimes you need to sacrifice one to get the other.
Do you have a heat sink and fan on it?

No I don’t have a heat sink or fan on it, I’m not even sure you can get one in there. But if you can I would be willing to go that route. I know it’s running too hot based off of the finger test, and based off of the temps in my 2wd slash, which is geared way higher. (Yes I know it has less load on it because it is a 2wd, but still this Smt is geared way low) It has the traxxas 3500kv motor in it, and they’re both running the same 2s battery. Idk it just surprised me because of how hot this motor is and how I thought it was geared low enough.

 

[Tunedfrog]

The Gravedigger I know is a stunt truck and not really designed for a lot of speed.
Good luck with your project. Sorry I couldn't help.

 

[jakehoek]

The Gravedigger I know is a stunt truck and not really designed for a lot of speed.
Good luck with your project. Sorry I couldn't help.

Thanks for the effort tho! Tried to put as much information out there as possible. No worries.

 

[nino]

Gearing up could actually help, I've had that in a light 2wd short course truck. A brushless motor is not happy with running idle, so running wot all the time with little resistance can be just as bad as overloading it.

And/or try to install a fan somewhere around the motor... I don't use heatsinks or fancy mounts anymore, just ziptie the sucker to the motor.

 

[RustyUs]

Moving from a brushed setup to a brushless setup is a perfect scenario for pinion gear swapping and temp checking for that new sweet spot. The #1 tool in this hobby is your brain, and right behind that is an infrared thermometer. Using fingers to do temperature checking is problematic as everyone's skin is not the same... every finger is not the same . I'm a sensitive guy , my fingers say Ouchy very quickly these days now that my calluses have disappeared.

Totally agree that under gearing is probably the issue here.

 

[jakehoek]

Gearing up could actually help, I've had that in a light 2wd short course truck. A brushless motor is not happy with running idle, so running wot all the time with little resistance can be just as bad as overloading it.

And/or try to install a fan somewhere around the motor... I don't use heatsinks or fancy mounts anymore, just ziptie the sucker to the motor.

Alrighty, that’s what I was hoping. Thanks for the fan idea

Moving from a brushed setup to a brushless setup is a perfect scenario for pinion gear swapping and temp checking for that new sweet spot. The #1 tool in this hobby is your brain, and right behind that is an infrared thermometer. Using fingers to do temperature checking is problematic as everyone's skin is not the same... every finger is not the same . I'm a sensitive guy , my fingers say Ouchy very quickly these days now that my calluses have disappeared.

Totally agree that under gearing is probably the issue here.

Yeah I need to get one lol.