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BBSHD noise, not pawl or nylon gearing - stator?

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    BBSHD noise, not pawl or nylon gearing - stator?

    My BBSHD build has a couple thousand miles on it, and was running fine pulling hard coming up hill yesterday, when it suddenly started making a grinding, almost a knocking noise. I've torn it down, removed the big steel crank gear with the pawl, and still got the noise running the motor with throttle.

    Now, I've got the motor loose and separated from the nylon reduction gear and controller. I can't get the nylon gear cover open but it is moving by itself smoothly and without any resistance, as it did when I shoved Mobile 28 through the cover opening (couldn't get the cover off then).

    I'm down to wondering about a cracked magnet, or something else that might be causing noise right at the stator. I can't seem to pull it out of the coil cavity, but rotating is is not smooth. Of course, it is unsupported on one end being free from the reduction gearing, and I'm not sure if I can expect it to move smooth halfway installed like that.

    Could I be looking at a cracked magnet? I can see them, nothing obvious... Looking for any advice before I lay down $500 for a replacement motor...


    p.s.: here's some video after I crammed in as much Mobile 28 as I could get in without being able to remove the internal nylon gear cover. No change in the noise, and is the same as it was under load when it suddenly started. Sorry about the portrait orientation, I tried to get it rotated after the phone recorded other than I meant, but YouTube just put it back:

    I got the rotor out of the stator coils, and nothing obvious jumps out at me, although it does look like there are some areas where there may have been contact and maybe the source of the noise? Didn't see junk coming out... Lots of Mobile 28 on the nylon gear too, seems smooth.


      Whelp, I finally got determined to open that nylon gear cover, and after destroying the screw and leaving the shaft behind, I got it opened up. Everything looked good, so I reassembled without the nylon gear to see what it would sound like with that part of the drivetrain free. Not good, about the same.

      So what's next? Try a new rotor and/or stator coil set? Which first? Both?
      Last edited by APailthorp; 05-11-2019, 07:16 PM.


        sounds like a bearing(s). I just got my BBSHD a few months ago but with some experience in RC helis with their brushless motors the bearings would go and have similar symptoms. Bearings may exhibit different behaviour under load
        Spark plug timing correct??? just kidding.
        Last edited by Renn; 05-11-2019, 08:03 PM.


          It does sound sort of like bearing noise but I don't think that's it. At this point I'm able to manipulate the bearings on both ends and they feel fine by hand. Just setting the rotor into the bearings and giving it a spin also seems smooth.

          I think it's got to be something wrong between the rotor and the stator but I haven't spotted the source of the interfere. I think the scuffing apparent in the first set of pictures might be meaningful, I just wish I could figure out why it started happening and what to replace to fix it.


            I got this email today:
            Dear Aaron,

            We received a batch BBSHD rotors last week, but all are booked by our one of US customers
            Or can we ship you the other items first?
            Sorry for that!.
            Well nuts!

            Anyone know who that US customer is?

            I'm asking of course, but would be happy to make direct contact. May well just be a bearing, but I'm having a hard time figuring out my next step, lacking extra parts to swap.


              I suspect you're on the right track on rotor/stator interference.

              How about "painting" the rotor and stator with a permanent marker or machinist blueing then running it, to see where there's contact (other than the spot you already suspect). "Pulling hard" on a hill sounds like a slight overheat, maybe solvable by filing down the outside of the rotor a smidge and/or making sure the stator windings are tight/not shifting.
              2nd build, 2018 Crust Scapegoat, BBS02 or BBSHD, Rohloff IGH
              3rd build, 2018 Crust Evasion step-thru, BBS02, Shimano Nexus INTER-3 IGH
              4th build, 2016 Salsa Marrakesh flatbar frameset, BBSHD, Alfine 8 IGH

              Visit the forum knowledge base


                yeah, the above marker stuff should help to detect the issue. i used the same technique before.


                  I didn't attempt to repair the interference between the motor rotor and the stator coils and instead just opted to buy a new motor core for $200 from Luna.

                  That resolved my problems. I still haven't figured out exactly where the damage is that led to the noise you can hear in the second (of three) video linked above (where nylon gear removed, nothing moving but motor core), but suspect that either the bearing buried under the core in the bottom of the coil well is damaged (although it feels fine under finger load) or the cup that is seats into has opened up enough to allow some movement... Probably from allowing the motor to overheat.

                  I'm not sure what I'll do with my old coils and core - I'd like to repair them for a spare, but am not sure if I can fix it, given I don't know if the damage is a bearing or where the case secures it.


                  • ncrkd
                    ncrkd commented
                    Editing a comment
                    Good - back on the road.