Brushless runs hot...advice

[KyleRC]

I use kinexsis 3000kv on 3s I run stock gearing(I assume is the problem) but it runs hot and want temps down any suggestions on pinion size

 

[WoodiE]

What are your temps at @KyleRC?

 

[KyleRC]

Sorry it sounds stupid. The motor I have isn't supposed to run above 160 I have a temp gun coming right now. 130 usually feels like it's burning right?

 

[sc302]

Try going to a 12 or 14 tooth.

 

[KyleRC]

Try going to a 12 or 14 tooth.

The lowest I can go is 17 I'll try that and make sure I'm not geared too low. If it gets hotter I'll gear up.

 

[sc302]

You want to go up not down.

 

[KyleRC]

You want to go up not down.

I'll try a 19 tooth tomorrow and see how it works I'll keep you posted.

 

[sc302]

I run a 19 tooth on a stampede 4wd and a 3700kv. Gotta move up more but it has a lot of low end tq. Runs pretty cool, though it has a motor fan.

 

[KyleRC]

I run a 19 tooth on a stampede 4wd and a 3700kv. Gotta move up more but it has a lot of low end tq. Runs pretty cool, though it has a motor fan.

On 3s?

 

[sc302]

nope. 2s. That gear will suck on a 3. Too much torque.

 

[Jeb]

I was running a 22t pinion on 4000kv. It was getting wicked hot and cooked the motor bearings and actually bent all the teeth on the pinion into the shape of a wave not a gear. That was on a plastic spur gear as well. It had incredible top speed, but it seemed too much for the truck. I switched back to the 18 tooth and it doesn't get as hot. I'm experimenting with a heat sink and cooling fan, I'll let you know if it helps. Bigger pinion = more top end, but more motor strain and higher temperature. Smaller pinion = more torque, less top end, less strain on the motor, and cooler running temperatures.

 

[KyleRC]

nope. 2s. That gear will suck on a 3. Too much torque.

I run 3s as my main battery I'm

I was running a 22t pinion on 4000kv. It was getting wicked hot and cooked the motor bearings and actually bent all the teeth on the pinion into the shape of a wave not a gear. That was on a plastic spur gear as well. It had incredible top speed, but it seemed too much for the truck. I switched back to the 18 tooth and it doesn't get as hot. I'm experimenting with a heat sink and cooling fan, I'll let you know if it helps. Bigger pinion = more top end, but more motor strain and higher temperature. Smaller pinion = more torque, less top end, less strain on the motor, and cooler running temperatures.

do you happen to know the temperatures exactly?

 

[Jeb]

I run 3s as my main battery I'm

do you happen to know the temperatures exactly?

Just burned to touch it and smoking motor bearings. I'll get more scientific while I experiment with this cooling fan. 160 is optimum, but they can take up to 180 in short doses. 200 starts demagnitizing the brushless motor. Just learning as I go...fast

 

[KyleRC]

What are your temps at @KyleRC?

My temps are around 160 I don't like it. I run 3s as my main battery. On 18 tooth.

 

[Jeb]

My temps are around 160 I don't like it. I run 3s as my main battery. On 18 tooth.

I've been testing temps this weekend. Mine was running at 147 after a hard run mostly with the fan running. I ripped the wires out of the receiver in a crash towards the end of the run and I did up the pinion to a 20t. Mad slop in the diff so I ripped it apart and put new bearings in, but it's still sloppy. Just repacked it 3 weeks ago. I can see new diff gears in my near future. I built mine with full metal except the spur, and even the plastic diff has metal gears inside it, so I'll probably just use those. On another note, I checked the temp on my sons 20T brushed motor after bumping his pinion up to a 19t and he was at 183, so maybe the fan should go on his motor. He loves just burning long dounuts. He did get second in the kid's group race this weekend so he's coming along nicely. I totally biffed my race because I packed for a family camping trip for 16hrs the day before and only slept an hr before the race. Too wound up and had the suspension way too stiff. Here's some pics from the race.

 

[Jeb]

View attachment 1866 View attachment 1867 View attachment 1868 View attachment 1866
I've been testing temps this weekend. Mine was running at 147 after a hard run mostly with the fan running. I ripped the wires out of the receiver in a crash towards the end of the run and I did up the pinion to a 20t. Mad slop in the diff so I ripped it apart and put new bearings in, but it's still sloppy. Just repacked it 3 weeks ago. I can see new diff gears in my near future. I built mine with full metal except the spur, and even the plastic diff has metal gears inside it, so I'll probably just use those. On another note, I checked the temp on my sons 20T brushed motor after bumping his pinion up to a 19t and he was at 183, so maybe the fan should go on his motor. He loves just burning long dounuts. He did get second in the kid's group race this weekend so he's coming along nicely. I totally biffed my race because I packed for a family camping trip for 16hrs the day before and only slept an hr before the race. Too wound up and had the suspension way too stiff. Here's some pics from the race.

Oh yeah, you don't need a fancy temp gun to test motor temps, just use a digital meat thermometer. Slide it in under the motor guard and you'll know what's going on in there. $12 at Walmart.

 

[sc302]

Oh yeah, you don't need a fancy temp gun to test motor temps, just use a digital meat thermometer. Slide it in under the motor guard and you'll know what's going on in there. $12 at Walmart.

While not at walmart, not really fancy.
https://www.amazon.com/gp/aw/d/B019...ometer+gun&dpPl=1&dpID=41Y5W8Q-7aL&ref=plSrch

 

[Jeb]

While not at walmart, not really fancy.
https://www.amazon.com/gp/aw/d/B019...ometer+gun&dpPl=1&dpID=41Y5W8Q-7aL&ref=plSrch

Already had plenty of meat thermometers. Grillin' is another passion.

 

[Jeb]

View attachment 1866 View attachment 1867 View attachment 1868 View attachment 1866
I've been testing temps this weekend. Mine was running at 147 after a hard run mostly with the fan running. I ripped the wires out of the receiver in a crash towards the end of the run and I did up the pinion to a 20t. Mad slop in the diff so I ripped it apart and put new bearings in, but it's still sloppy. Just repacked it 3 weeks ago. I can see new diff gears in my near future. I built mine with full metal except the spur, and even the plastic diff has metal gears inside it, so I'll probably just use those. On another note, I checked the temp on my sons 20T brushed motor after bumping his pinion up to a 19t and he was at 183, so maybe the fan should go on his motor. He loves just burning long dounuts. He did get second in the kid's group race this weekend so he's coming along nicely. I totally biffed my race because I packed for a family camping trip for 16hrs the day before and only slept an hr before the race. Too wound up and had the suspension way too stiff. Here's some pics from the race.

I inspected the sloppy differential again and compared it to the original plastic one I never installed. All the play is in the diff housing where the axle shafts come out. Can't really do anything about that. The bearings are new so the gearing will turn smooth. It's just sloppy axles. Guess I'll just run it till it's toast.