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R/C Brushless Motor Bearings Replacement Guide
How to change the ball bearings in an electric brushless motor for a radio control car, truck, plane, helicopter or boat.

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Dynamite Fuze DYN4950
Fast Eddy New Bearings
This DIY repair tutorial was specifically written to assist owners of the Losi TEN-SCTE Troy Lee Edition RTR (ready-to-run) radio control short course 4WD truck in replacing broken or worn out ball bearings in the Dynamite Fuze DYN4950 3900kv 4 pole 540 size brushless electric motor.

After 1000's of laps at an indoor clay track, the front ball bearing in my brushless motor failed and literally exploded.

I asked the staff member at the R/C shop for a compatible new bearing, but he wanted to sell me a new $100 motor.

I contacted Dynamite R/C (owned by Horizon Hobby) and they told me that the bearing size is 5x13x4mm (5mm by 13mm by 4mm) for the DYN4950 motor.

To complete this procedure, you'll need a set of hex drivers.

Loosen Motor Mount Bolt
Remove Side Bumper Rail
Pull Out Brushless Motor
Some symptoms of an electric brushless motor that needs new bearings include excessive heat build up, an abnormally hot ESC (electronic speed control), ESC thermal shutdown, shortened run times, hot LiPo batteries and/or reduced top speed.

The first step is to remove the brushless electric motor from the vehicle.

For the Losi TEN-SCTE, you'll also need to remove the side bumper bar or "rail".

I recommend using the Bondhus hex screwdrivers since they have a lifetime warranty and excellent reviews on Amazon.

Then loosen the hex bolt on the motor mount.

Slide the brushless motor out of the mount.

Loosen Pinion Gear
Loosen Base Cover Screws
Base Cap Screws
Loosen the small screws on the rear cover the brushless motor with a hex driver.

Set the small screws aside in a safe place such as a plastic container.

Pry Off Rear Cover
Rear Cap Removed
Pull Out Rotor (Magnets)
Gently pry off the rear cover with a small flathead screwdriver.

Use a pair of needle nose pliers to pull out the rotor (part in the middle of the motor that spins).

Slide the remaining parts of the old ball bearing off the rotor.

Remove any remaining parts of the broken ball bearing from inside the motor housing.


Pull Off Broken Bearing
Brush Rotor Clean
Slide On New Bearing
Use a soft bristle brush such as a toothbrush to clean off any debris from the rotor and the stator (copper windings inside of the motor housing).

Make sure that the motor shaft is clean.

The correct replacement ball bearing size for the Dynamite Fuze DYN4950 540 size brushless motor is 5x13x4mm.

Slide the new ball bearing on to the front shaft where the pinion gear is usually attached.

Stator (Copper Wires)
Replace Rotor - Install Bearing
Rotor In Housing
Carefully insert the rotor into the motor housing.

Push on the rotor to carefully seat the new ball bearing into the mount in the front of the motor.

If you prefer, you could use a pair of long needle nose pliers to place the new bearing into the front of the motor.

To check to see if the new front ball bearing is securely installed in its mount, you can pull out the rotor and look inside.

Pop In Rear Ball Bearing
Line Up Rear Cover
Pop Cover In Place
Snap the new rear ball bearing into the plastic rear cover of the motor.

Line up the rear cover and push it back into place.

Replace Tiny Hex Screws
Motor Re-Assembled
Replace Motor On Car
Replace the small hex screws by turning them in the clockwise direction until they are snug.

Secure the pinion gear to the motor shaft. Re-install the motor into the vehicle.

To prevent the motor mount screws from vibrating loose, use a small amount of blue medium Loctite threadlocker.

Carefully test the new ball bearings by operating the brushless motor at a slow speed at first. Monitor the outside temperate of the motor's "can". If the motor feels abnormally hot, the new bearings may not be spinning easily.


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