Senton Issue with overheating

[JacobLS1]

I upgraded my Senton with an Onyx 4000kv and I can't seem to run it for more than a few minutes. The motor cuts out but the steering servo still works.

Here's what I have:

Senton Mega
Onyx 4000kv motor + ESC(both with fans)
Blx slipper assy 19/57 gearing
3s Goldbat 5200mah battery
XT90 connectors
20Kg servo with no ext BEC

What I've done:

The deans connectors were getting hot, so I replaced them with xt90s; the truck is more responsive, but this didn't fix it.
I've tried a 14t and 19t pinion. 19t just heats up the motor quicker.
Added a heatsink/fan combo to the motor, no thermal paste.
Re-calibrated the esc
Re-seated the bullet connectors

Some info:

The final setup runs longer on full throttle passes(attempts) on asphalt vs a dirt track with some loose spots
The truck has a 20kg servo without an external BEC, I heard this can overheat the esc?
The wires from the motor to esc get warm
Today, it lasted 4 minutes with on and off throttle, texting and letting the truck sit for a few seconds at a time. Throttle limited to 75% on remote, and using throttle control up to maybe 80% trigger on aforementioned dirt track. Esc was too hot to touch, motor was pretty hot. Mid 80s (F) today
LVC is set at 3.4v
I haven't used a heat gun for temps, just the old "can I touch it for a few seconds, or is it too hot to touch".
When I went to charge the battery, it starts charging from 50-75%(yellow flashing on my charger)
My granite has a similar setup (Onyx 3200kv, 14/57, same h/s+fan, same battery) and runs much longer with much more abuse.

What can I do to make it run longer? What gearing should I be looking at?

 

[slick2500]

That motor has too small of a can size for that high of KV. That motor is better suited for vehicles like a Slash 2wd or Bandit.

The sweet spot for these vehicles seems to be 3000-3500kv motors for 3s running.

 

[JacobLS1]

That motor has too small of a can size for that high of KV. That motor is better suited for vehicles like a Slash 2wd or Bandit.

The sweet spot for these vehicles seems to be 3000-3500kv motors for 3s running.

Can you elaborate? I don't understand. The can size is 540, and the KV is too much for the 540 size? However, it will work in 2wd vehicles?

Thanks

 

[Edough13]

Can you elaborate? I don't understand. The can size is 540, and the KV is too much for the 540 size? However, it will work in 2wd vehicles?

Thanks

So higher kv produces more RPMs/speed and higher heat, but lacks on torque to move a heavier car. Lower kv is more torque and efficiency/less heat and moves more weight. That motor would be good for a really light small car. Also your gearing is way to high at 19/57 and that's another reason your overheating with that high kv you should be running like a 12-13t pinion to keep heat down. But the big picture is it's not producing the torque needed to move the rig and it's heating up cause it's way over geared. Like slick said 3000-3500kv is the sweet spot I'd suggest closer to 3000kv as it will run a bit cooler and run more efficiently

 

[slick2500]

Too add to what @Edough13 said and expand upon what I said 540 motors are not the best choice for a 1/10 4wd vehicle they just do not have enough torque to move the vehicles efficiently, that is why so many people burn up the stock brushed motors in the Mega lineup. The Mega models to stay brushed and not burn up motors all the time really need a 775 or 880 sized brushed motor( I would not try to run a motor like that on the stock esc, you would want a Hobbywing 880 or Traxxas EVX2). Ideally you would want a 3660 or larger motor for the Arrma 4x4 platform.

 

[GraniteFox]

Moving a 4wd drive train takes torque. The combination of high kv and smaller can size cannot push the vehicle with that gearing. I would also imagine some cogging upon initial start. Go way down on the pinion...maybe 10t or 11t. Even then you may end up with issues due to even minor binding or resistence in the drivetrain. Swap out the motor with a 3660 or larger motor around 3000kv. Here is a 3665 hobbystar that would be good https://www.rcjuice.com/motor-esc/b...le-brushless-sensorless-motor-waterproof.html

You could use the 3660/550 as well but for the $$$ I would go 3665. Pair that with a 15-20t pinion and you are good to go.

 

[dure16]

Too add to what @Edough13 said and expand upon what I said 540 motors are not the best choice for a 1/10 4wd vehicle they just do not have enough torque to move the vehicles efficiently, that is why so many people burn up the stock brushed motors in the Mega lineup. The Mega models to stay brushed and not burn up motors all the time really need a 775 or 880 sized brushed motor( I would not try to run a motor like that on the stock esc, you would want a Hobbywing 880 or Traxxas EVX2). Ideally you would want a 3660 or larger motor for the Arrma 4x4 platform.

Would a 775/880 fit into the stock mega motor mount?

 

[JacobLS1]

Thanks for all the information, it's incredibly helpful. I read some bad information on kv rating not affecting gearing and couldn't find anything stating otherwise, but I had my suspicions. I have a 12t pinion I can use in the mean time.

With a new motor, would I need to find something that draws at or less than 70a since my ESC is rated at 70a/230a(max)? The hobbystar 3665 is rated at 80a with 4s, would that draw less with 3s? Also, my ESC has 3.5mm plugs. If I got something with a different size plug, is it as simple as just soldering on new connectors?

 

[slick2500]

Would a 775/880 fit into the stock mega motor mount?

You would have to drill new holes iirc. I will check.

You would need the BLX motor mount for a 775 motor.

 

[GraniteFox]

Agree, need a new mount To support the weight of the motor.

 

[slick2500]

Agree, need a new mount To support the weight of the motor.

The holes won't line up. Hole spacing is wider on the 775. Not 100% sure the BLX adjustable mount will work without modifications either as I didn't feel like tearing either of my 3s apart. But I can if you really want me to know.