Converting the Wltoys 104001 to Brushless: My Sensored Installation

With the centre differential installed, it was time to replace the Wltoys 104001 electronics. In this video I install a sensored system and also explain the simpler alternative I had used previously.

What Needs Replacing

The conversion requires a brushless motor, compatible ESC, three-wire servo and a receiver that binds to the chosen transmitter. Changing only the motor while retaining all the original electronics is not enough.

I removed the servo, ESC and motor. I reused the servo mounting and checked the arm and screw fit on the replacement. The motor-mount screws were so difficult to remove that I ended up using another mount.

Two Different Installations

My earlier installation used a budget sensorless system that worked well. The description lists a 60A, 3500KV Surpass combo as an alternative.

For this installation I used a sensored Hobbywing QuicRun 10BL120 and an 8.5T motor. Do not confuse that ESC with the 120A Surpass combo linked as an option, or other QuicRun versions sharing part of the name.

At this stage I presented a 33-tooth pinion with the project’s spur gear. It belongs to my particular combination, rather than a recommended ratio for any motor, battery or use.

Rotation Direction Complicated the Installation

With my motor and ESC combination, applying throttle made the car try to reverse. I wanted to retain sensored operation and did not resolve the direction through that ESC’s programming.

My solution was to reverse both axle differentials, removing internal tabs that prevented that positioning. Modifying the housings only makes sense after checking the specific installation.

This is not mandatory for every brushless conversion or sensored system. Check the motor and ESC options before modifying housings. Equally, do not automatically apply the phase-swapping approach used on sensorless systems to one requiring the correct phase/sensor relationship.

Afterwards I checked that both axles drove in the same direction. Reversing only one would make them work against each other.

Differential Maintenance and Assembly

While dismantled, I cleaned the internals and replaced the lubricant. I used 70,000 cSt silicone at the front and 10,000 cSt at the rear. In the centre I mixed both without a measured ratio, so I cannot state a final viscosity.

I started all screws, tightened progressively and checked rotation. Closing the housings, I also checked mount positions and symmetry; geometry cannot be assumed unchanged after loosening everything.

Receiver, Soldering and Wiring

On this receiver, steering connects to channel 1 and the ESC to channel 2, checking signal, positive and negative markings. Verify the physical pin positions on each receiver.

My installation required soldering. A faulty joint meant stopping the check and repairing it. At the end I secured the components and kept every cable away from the spur gear and driveshafts before closing.

What Comes Next

The recording ends with the conversion assembled and bench-checked. It does not include a complete track test or measured top speed. Cooling and further testing remain part of the project’s development.

See also the body repaint and original review.

Parts References

The mount and pinion links include the correction left in a channel comment. The servo retains its Amazon reference; the AliExpress link repeated for several parts remains under review. The two combos are alternatives from the description, rather than two systems fitted to this car.