Six brushed Red390 motors available

[keilau]

Received all 6 motors this afternoon. Thank you!

Good that they find a good home.

[DavidN]

Good that they find a good home.

We are thankful! Which tanks do you think these are good for?

[keilau]

We are thankful! Which tanks do you think these are good for?

The Red390 runs at 25000rpm (vs 15000rpm of the standard HL380). It is better suited for the bigger and faster modern MBT such as Abrams, Leopard2A6, Challenger2, T-72/T-90, Merkava. I also use 390's on my Pershing, M60A1, T-34/85 where they will have excessive scale speed, but are fun to drive in open space. The only tank that the 390 cannot physically fit is the Sherman.

[Evan D]

I don't think they are any higher RPM but they have more torque. I have them in my metal version (treads, wheels, gear box) Leopard, Challenger II, Merkava, and T90.

[keilau]

I don't think they are any higher RPM but they have more torque. I have them in my metal version (treads, wheels, gear box) Leopard, Challenger II, Merkava, and T90.

For small brushless motor like the Mabuchi 300 series, the torque is a linear function of the rotational speed. The 390 motor does have more torque because it runs faster. You can find the detail information at the Mabuchi website.

https://www.mabuchi-motor.com/company/network/america.html

The quality control of the red390 and blue380 motor are rather poor with a lot of rpm variation. I actually built a small test rig using a spare HL gearbox and a portable tachometer to measure each motor to select matching rpm pair for use on my RC tanks. It helps since the HL transmitter does not have trim. There is an old and lengthy thread on "red or blue motors" that you may find interesting:

https://www.hobbysquawk.com/forum/rc-cars-tanks-trucks-and-more/rc-tanks/236451-red-or-blue-motors#post361215

The track rpm cannot be used to determine the motor raw rpm because I do not know the ratio of track length to equivalent sprocket diameter. I built a simple test rig to test motor rpm, using a spare HL gearbox. The shape and diameter of the measurement wheel is not important. I just need to hold the tachometer red LED spot to the marker.

Using 8.0 volt Li-Ion, the HL grey stock 380 measured at 15,000 rpm. The grey 380 runs at 40°F above ambient. The 4 better quality motors all run 20 degrees or more cooler. The Mabuchi RS380PH-3270, Tamiya 380SP, HL Red 390 and MxFans 390 have rotational speed of 14,000, 17,500, 26,000 and 30,000 rpm respectively.

Any comment on my simple approach and comparison of data is much appreciated.

[Evan D]

What 380 is the stock HL using? You show that some 380's have different rpms and some 390's do too.

[keilau]

What 380 is the stock HL using? You show that some 380's have different rpms and some 390's do too.

The HengLong RC tank come with the grey380 motor which is a knock-off of the Mabuchi 380. It runs at about 15000rpm, but runs hot at 40°F about ambient. The 390 that you use has an internal cooling fan and runs 20°F cooler. It should give you reliable service in your large MBT RC tanks. Below is the motor case temperature measurement in a HL Leopard2A6 with all metal drive chain and Tamiya track.

[keilau]

The HengLong grey380 runs hot because theu cut corner to save cost. It uses high friction sleeve bearing for motor axle instead of the ball bearings in the Mabuchi motor. If I have to use 380 motor, I pay the premium to get the Tamiya SP 380 which is bonafile Mabuchi motor and runs much cooler than the HL grey380. Mabuchi does not sell to the retail market.