Motor Bearing Replacement

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Tools
  • C-clip pliers
  • M10 tensioner
  • Loctite 648
  • Hub puller (to extract the bearings)
  • Replacement bearings (front and rear are both 6006-2RS on an FX used below)
Steps
  1. Remove the motor
  2. Once you have the motor out of the bike, you can pull it apart.
    It is actually quite easy to pull apart, but requires a lot of force.
    You can built a little chair (width of the plate, you put it on the cooling wings) with an M10 tensioner.
    Then you bolt an M10 eye-bolt on the pulley so you can pull on the shaft really hard (about 200lbs), and the rotor will pull out on the shaft along with the drive plate and bearings.
    Warning Warning: Once you have the shaft and rotor out, be careful as it is highly magnetic and you can get your fingers pinched quite easily on it.
    At that point, I found that the rotor is loose on the shaft.
    You have to remove the rear bearing, remove the c-clip holding the rotor laminations on the shaft, use a marker or something to mark the front and back of the rotor and how it is aligned on the shaft because you are going to take it off.
    Warning Warning: It is important that it goes on in the exact same direction, otherwise the motor could spin backwards.
  3. Once you have the rotor and the shaft labeled so you can get them back together exactly the same way, slide the rotor laminations off the shaft.
  4. Clean the shaft and the inside of the laminations.
  5. Apply a lot of loctite 648 on the shaft and lamniations, then slide them back together.
    Ensure that they go together the same way that they were before, and that the loctite 648 gets well-distributed between the shaft and the laminations to make a solid bond.
  6. Put the c-clip back on, put the bearing back on (or put a new bearing on since removing a bearing without damaging it is quite hard, the front and rear bearings are both 6006-2RS).
    When you put the new bearing on, make sure you just push on the inner race for the press fit, if you push on the outer race it will transfer the force through the balls and likely damage them.
    The bearing should be a press fit, if it slips on or off easily, you should glue it on with the loctite 648.
  7. Let the 648 cure for a few hours before putting the motor back together.
  8. To put the motor back together, just do the same thing you did to pull it apart, but opposite.
    Ensure that the wave-spring is still in the bottom of the bearing pocket at the bottom of the motor.
    Warning Warning: Be careful to not let the rotor slam back into place, that could damage the bearing
    Make sure you control the rotor: use the little chair and unscrew the tensioner to let the magnetic forces pull it back in slowly.
    Once it is almost all the way in, the bearing will catch on the bearing pocket.
    At that point, it might take a little jiggling around and some force on the end of the shaft to get it to pop into place, then it could take a bit more force to get the drive-plate to re-engage with the stator case.


References