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Changing the motor core on the BBS02

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    Changing the motor core on the BBS02

    This tutorial is to change a defective BBS02 motor core.

    You will need the core itself , Click here.

    You better don't take any chances and order a paper gasket, Click here.

    Tools needed:
    • You will need a small blade or razor
    • Set of Allen keys (Hex)
    • Philips head screwdriver
    • Flat head screwdriver
    • Silicone
    • Possibly some white lithium grease (stuff used by Bafang : Unical Aviation Synthetic Grease AG-11)
    Start by removing the motor from the bike, it's not necessary but so much easier to work on. Specially since you will have to remove the silicon over the plug and wires.

    1) Remove the plastic secondary gear cover. (don't pay attention on this photo the controller is already removed)

    Inpect the secondary gear for:
    • Lack of grease (black moly grease)
    • Dirt mixed in the grease
    • Creamy grey consistency (water mixed to it)
    If there is dirt or water mixed or you are over 1000 miles on it I recommend going for a full cleanup and re grease using better stuff like Mobilgrease28.

    I will do a Knowledge base thread on it and will link it here or use this link to Karl's amazing blog

    Click image for larger version  Name:	DSC00002 (1).jpg Views:	1 Size:	521.6 KB ID:	27440

    2) remove the 3 hex bolts that hold the controller and gently pull on it. Unplug the 3 bigger phase wire connectors (yellow, green and blue wires) and unplug the smallest black JST connector .

    Next remove the silicon around the 3 phase wires using a small flat head screwdriver and the blade, pay attention not to cut the insulation on the wires.

    Move on to the white recessed connector at the bottom, use a screwdriver to remove or cut the silicon around it, On the picture you see my screwdriver is pointing to a place on the connector that is a plastic lock the hold the connector in place, you have to slide a screwdriver in between the latch and the motor casing and press toward the plug to unlatch it. Gently pull on the connector while doing it.

    Now you can set the controller aside.

    Put back the plastic cover over the secondary gear.... just so you won't put grease everywhere!!! Click image for larger version  Name:	DSC00001.jpg Views:	1 Size:	589.9 KB ID:	27441

    3) Remove the clear silicon sleeve over the 3 phase wires and save them for later.

    Flip the motor to the order side and remove the 4 hex bolts that secures the motor to the casing.

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    Last edited by Sebz; 02-07-2017, 06:07 PM.

    4) This part is tricky:

    There is a paper gasket wedged in between the motor and casing, so if you have a spare well just use a screw driver and work around it to separate the 2 parts. Be careful the casing is made of soft alloy.

    If you don't, take the motor in your hand and try to pull on each end to work into a little gap (wiggle it), then gently .... very gently work on one spot at the time with a flat screwdriver, be careful the casing is made of soft alloy. Click image for larger version  Name:	DSC00002.jpg Views:	1 Size:	654.4 KB ID:	27445
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    5) Separate the 2 part slowly and let the phase wires pass through the holes. Pay attention to the gasket and put it aside.

    if the black rubber grommet fell off, replace it back exactly like this (notch goes where the screwdriver is pointing)

    *This motor was cleaned before the picture was taken, the is no grease what so ever.


    Inspect the nylon gear, no need to remove it, just turn it and looks for damage or black moly grease that might have gone from the secondary side to the primary side. If you have black grease on the nylon you will need to remove it, clean the mess and apply a new grease to it...

    Link to Karl's blog on the Mobilgrease28
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    6) Put the old core aside and take the new one, put the gasket on it and put the phase wires in the respective holes.

    7) Grease the motor gear using white lithium grease (Unical Aviation Synthetic Grease AG-11) if you don't plan on removing the Nylon gear and clean everything to switch to a different grease. Like the Mobilgrease28.

    8) Put the core back in the casing and pay attention not to rip the gasket, if by any chance you do, you can make a gasket using the silicone tube you already have! Hand tight the hex screw, give it a good torque (just by hand is enough), the motor needs to sit flush to the casing. Click image for larger version  Name:	DSC00013.jpg Views:	1 Size:	756.9 KB ID:	27456

    Last edited by Sebz; 02-07-2017, 06:23 PM.


      9) Put some silicon around the phase wires, make sure they are centered in the middle of the hole, put some silicone around the hall sensor plug (big rectangle connector), let it dry before continuing.

      Once dry, put the clear sleeves on the bullet connectors.

      Click image for larger version

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      10) Remove the plastic gear cover and install the controller back in place, now it time to use a bit of dielectric grease on the connectors if you like, also make sure your gasket is is not like mine on the previous picture, screw tightly no need to torque them too much you will crush the gasket.

      11) Put back the plastic cover and be careful not to over tight the philips head crew you will crack the cover.


        Thanks Sebz,

        I addition to being helpful these in depth tutorials can have a positive effect on the forum. Over time, other sites tend to llink to them as a references. This increases the entire position google ranking :).

        What is the green mat surface you are using as a work surface? Is it easy to clean? It looks much nicer than the piece of hardboard I put over my benchtop for photos!



        • Sebz
          Sebz commented
          Editing a comment
          Thank you, we are here to share the knowledge to the world!

          The mat is a Hobbico cutting mat. I use it to solder, cut, work... It's fantastic, it can absorb impact too. quite thick and heavy duty.