How to Rebuild an Electric Bike Motor

Most electric bike motors are powered by DC, or direct current for two reasons. Direct current allows the speed of the motor to be controlled, which enables the rider to select a speed of the bicycle. In addition, direct current can be provided by a battery as opposed to a generator. An on-board battery serves as a portable power pack for the electric bike. In some instances, rebuilding an electric motor can increase the performance level. Rebuilding an electric bike motor begins with removing the motor from the bike.

Things You'll Need

  • Socket and ratchet
  • Box wrench
  • Nut driver
  • Clean rag
  • Fine steel wool
  • Non-residue spray cleaner
  • Spray lubricant
  • Armature brushes
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Instructions

    • 1

      Use a socket and ratchet or box wrench to loosen the motor mounts on the bike. Move the motor toward the drive sprocket to create slack on the chain and remove the chain from the motor sprocket. Removing the chain is not necessary with a friction drive motor.

    • 2

      Disconnect the electrical wire leads that connect between the battery and the motor. Disconnect the speed control cable from the motor and remove the motor from the bike. Place the motor on a workbench.

    • 3

      Use a screwdriver to remove the armature brush covers on the motor. Lift the brushes out and discard them. Use a nut driver to remove the bolts on the back motor cover. Grip the sprocket or friction roller on the opposite end of the motor and pull the armature out of the motor housing. Clean the inside of the housing with a clean rag and set the housing aside.

    • 4

      Clean the copper armature with fine steel wool and non-residue spray cleaner. Be sure to clean each of the grooves on the armature. Clean any debris that's noticed on the magnets.

    • 5

      Stand the armature on the motor sprocket or friction roller. Spray the shaft bearing that's just behind the sprocket or roller with spray lubricant. Be careful not to over-spray lubricant onto the magnets or the copper armature. Wipe the inside of the motor housing with a clean rag to remove dust or dirt.

    • 6

      Reassemble the motor and install new armature brushes. Position the motor on the motor mount on the bike. Attach the chain or align the friction roller with the bicycle tire. Reinstall the motor mount bolts and adjust the chain or roller tension. Reattach the speed control cable and electrical leads.