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How hard is it to remove and replace a replacement bare axle in a DD hub motor?

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  • Tommycat
    replied
    Originally posted by luka View Post

    Do you have any idea where to find it?


    Have you had experience making with a turner?

    You may want to try posting on ES as there seems to be more hub motor riders posting there...


    Never made one, and would expect it to cost quite a bit to have one custom machined.

    Leave a comment:


  • luka
    replied
    It doesn't say anything on the engine.
    I can measure axle.
    Do you have any idea where to find it?
    Have you had experience making with a turner?

    Leave a comment:


  • Tommycat
    replied
    Sorry, I do not recognize what it might be... with out the manufacturer and model. It will be difficult to find a part. Any stamped numbers or markings?

    Leave a comment:


  • luka
    replied

    the motor is in the rear wheel, the power is 1kW and my voltage is 84V,

    here are a few more pictures if it can help

    Leave a comment:


  • Tommycat
    replied
    Hi luka,
    And welcome to the forum! :-)

    What is the make and model of the motor?



    Regards,
    T.C.

    Leave a comment:


  • luka
    replied
    Hi,
    Does anyone know where i can buy the rear axle for the hub engine? Like this.

    Leave a comment:


  • commuter ebikes
    commented on 's reply
    VERY insightful tips, Calfee. I didn't know any of that stuff, but I do have a Park Tool plastic faced hammer.

    This motor is a guinea pig and it is going on a test setup (electronic parts on a bare frame with no tires, saddle, etc.) used to make and test wiring harnesses. We'll see how the motor runs after I put it back together. This motor will probably spend its whole life on the test setup.
    Last edited by commuter ebikes; 04-09-2017, 08:46 PM.

  • calfee20
    commented on 's reply
    The middle picture in this frame where it says Correct. Well I can make it more correct. A piece of brass between the press ram and the axle will protect the threads. Lacking that a nut screwed on to the axle almost flush will share the load and help protect the threads.

    All this is dependent on the force needed during the operation. As you do more work with a press you will develop a feel for what you are doing and will get better at it. A little time from now you not have made that mistake with the windings because you will be able to look at an assembly and know where to press and where to support automatically.

    When you started this thread I was here on the east coast cringing and wishing there was a way to reach through the forum to help you.

    One of the best presses I ever used was an antique 4 ton arbor press. It had a 4 foot lever that you used your weight on to develop force. You really knew how hard to you were pressing with that rig. It was a work of Art, all steel and cast iron. It probably weighed 500 pounds and was over 100 years old.

    The last tool you should ever go to is a hammer. Speaking of hammers, get a good brass hammer and a plastic faced one is also good.

    Finally and slightly off topic you will know a good mechanic if you see he has a set of copper jaws for his bench vice.................calfee

  • commuter ebikes
    replied
    I have to do this a few more times because I am getting rid of all my 170 mm dropout parts and using only 190 mm dropout parts on all of my bikes.

    Next time I do this, I will be very careful to go easy on the motor. The first time, I was really good to the bolts, but after opening the motor I was rough on some parts as listed above. I was even rough on the snap ring.

    There is a medium cable tie (zip tie) attaching the motor wiring harness to the stator. This gets removed for the axle pressings, so one needs to remember to get a new cable tie back on there upon reassembly.

    And it is so important not to strip any of the side cover bolts.

    I use a high temp gasket compound from the auto parts store for the side covers. Zelena Vozila had no gasket.

    Here is a video of the action: https://www.youtube.com/watch?v=Cui3dNkg5SY
    Last edited by commuter ebikes; 04-09-2017, 07:07 PM.

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  • commuter ebikes
    replied
    After securing the Park Tool snap ring plier set, my buddy Lloyd came over on a Saturday night and we found out how easy and fun it is to push out and press in axles.

    The work surrounding the actual install is aggravating. I learned a few things the hard way:
    (1) take care not to abuse the copper winding or Hall sensor wires (as mentioned above),
    (2) use the hydraulic press to defeat the strong magnetic field between the stator and outer magnets. I foolishly tried to do it with a sledgehammer on the ends of the axle and mushroomed the axle threads a little (on both sides of the axle, of course!). I had to shorten each end of the axle 2 mm in order to get the threads back to normal.
    (3) make sure that the motor wiring harness clearance groove (the shiny surface in the photo below) has enough room for the wires to fit through the inner race of the bearing on the brake side cover plate. I assumed that my newly purchased axle would be ready for installation; this was not the case. It needed to be milled now another 2.3 mm or more. If I had taken a second to compare the used axle that I removed, I would have seen that the new axle didn't have enough room to get my wires through my side cover. As a result, I had to remove the new axle that I had just installed for the milling process, which I did on a bench grinder.

    Click image for larger version

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    Last edited by commuter ebikes; 04-09-2017, 06:44 PM.

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  • funwithbikes
    commented on 's reply
    Nice write up. I, for one, am trying to learn as 'you' go.

  • commuter ebikes
    replied
    At this point, I have the snap ring plier set (https://www.amazon.com/Park-Tool-Sna...ring+plier+set) coming. I also ordered four spare bearings (https://www.amazon.com/6204RS-Rubber...eywords=6204rs).

    I am really kicking myself for crushing the windings and Hall sensor wires. I may have hosed this motor; it will be interesting to rebuild and test it. I have four bikes and six of these motors, so I had two spares. This spare may now be a spare parts motor/guinea pig. Oh, well. Live and learn. Maybe somebody else will learn from my mistake.

    I have to press in longer axles in two other motors, so I will definitely be way more careful with those.

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  • commuter ebikes
    replied
    The Cromotor has spare Halls. I don't know why the magnets are so scratched up.

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  • commuter ebikes
    replied
    The magnetic field between the magnets is so strong that you have to slam the end of the axle down on a hard surface in order to remove the stator magnet from the hub motor body. You can do this from either end.

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  • commuter ebikes
    replied
    So if you are doing it correctly, you will have to remove a snap ring before pressing out the axle. In this photo, you can see the snap ring as well as the snap ring groove in a bare axle.

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