Exchange Planetary Gearing inside the Hub Motor

My hub motor makes uncharacteristic noises and no longer works properly / provides no or irregular propulsion.

  1. Turn your bike over and place it securely on the handlebars and seat / frame end. Place a soft pad, such as a towel or blanket, underneath to avoid scratches. Use an assembly stand / bike holder, if available.
  2. Loosen the axle nuts of the corresponding wheel and make sure that the spacers do not catch on the frame / gear shift.
  3. Remove the wheel, if necessary disconnect the motor cable from the rear wheel beforehand, which comes out of one of the two axle sides (if necessary open the controller housing, loosen 4x 3 Allen screws and motor cable connector + unscrew cable clamps / alternatively the connector is outside the controller housing and can be disconnected without opening - see picture below).
  4. Place the engine on a soft, non-slip surface to protect the axle and brake disc from damage. Also remove the axle nuts and shims/spacers and note their correct order.
  5. On the sprocket/cassette side there are 6x 3mm Allen screws of the motor cover – Open and remove them.
  6. Now you can carefully remove the motor cover together with the cassette / sprocket - spread your fingers between the sprocket / cassette and cover unit and press it upwards. Alternatively, you can also work carefully with a flat screwdriver and gently pry open the cover - be careful here that you do not cause any (larger) nicks / scratches, which could later lead to a leaking cover.
  7. Now you have direct access to the inner workings of the hub motor, consisting of the stator and rotor unit (see below) as well as the planetary gear that ensures the transmission of power to the wheel – the 250W / 500W / 750W Bafang and MXUS hub motors (Hub Motors) have a ratio of 1:5 here (18Z to 36Z to 90Z).
  8. Now remove the entire rotor unit by simply pulling it out while holding the motor housing/wheel. Make sure that the planetary gear is removed as well, since it is attached to the stator unit.
  9. Separate the planetary gear and stator unit or remove the planetary gear from the motor housing if it has already come off. The three nylon gears (white) may be worn and should be replaced together with the mounting plate.
  10. Then grease well – special electric motor gear grease is used for this purpose, which is extremely sticky and adhesive to ensure adequate lubrication and minimize wear.
  11. Reassemble the individual parts of the motor unit, making sure that it is neatly recessed into the motor housing.
  12. Then install the housing cover and make sure that it sits flat/level on the motor housing and is tight.
  13. Then remount the wheel on the frame, ensure the correct arrangement of the spacers during installation and take care of the brake disc. If necessary, loosen the brake caliper to avoid damage to the brake disc.
  14. Tighten the axle nuts sufficiently but carefully and turn the wheel by hand to ensure the wheel runs smoothly. Then reassemble and re-center the brake caliper.
  15. Turn your bike back over, check it for function, and listen for any noise coming from the engine.

EBS IPS Motor cable connector (9-Pin):

Hub motor interior:

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