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BBSHD with 2500 mi. started making a clicking sound

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    BBSHD with 2500 mi. started making a clicking sound

    Hi, I'm new to the forum. I installed a BBSHD on my Trek Fuel FS mountain bike about 8 months ago. I have 2500 miles on it. The motor has developed a clunking or clicking sound when pedaling. The sound is not constant or consistent, but it is frequent. I have greased the motor twice. Once at 1500 miles based on various forum recommendations and just recently to try and solve the clicking which also involved greasing the axle bearings.

    1. The sound occurs mostly when pedaling with the motor set at any speed and shifter in any gear.
    Video link:

    2. There is no sound when pedaling with the motor off.

    3. There is no clicking if I pedal faster than the set PAS speed.

    4. Motor mounts, crank and pedals have been checked and double checked and are tight.

    5. One of the clutch pawls seemed a little sticky, so I cleaned it and reinstalled. I can hear the pawls engaging when I turn the crank backwards. (Hmm, maybe I'm only hearing one or two engage?)

    6. I can make the sound by cranking the chain ring backwards, motor off, just locking it to the pedal as I do for cleaning and lubing the chain with the bike on the ground.
    Video link: (turn the sound up)

    There may be an answer here already, but my search hasn't found it yet. I hope someone who has dealt with this can give me some clues before I start taking it apart.

    Last edited by designerron; 11-14-2021, 08:24 PM.

    Have the BBSHD myself,... doesn`t sound like pawls, are you sure the motor isn`t striking the frame? Everything really tightened up?


      Originally posted by tommie View Post
      Have the BBSHD myself,... doesn`t sound like pawls, are you sure the motor isn`t striking the frame? Everything really tightened up?
      Everything seems really tight, and it happens on smooth surfaces as well as trails. I will loosen the motor and put a rubber pad between the housing and the frame just to make sure before I pull it off and take it apart. But to me it sounds like it is coming from inside the motor. Could it be an internal bearing that is worn?

      UPDATE: Thanks tommie for encouraging me to take another look at the motor mounting. I loosened it and installed a thin rubber pad and tightened it up again. I took it for a 12 mile ride on the trail, and it was mostly quiet. That accounts for the randomness of the sound. It's now apparent that 2500 miles of trail riding can change the motor position just enough to make a racket. But after worrying it was internal, I have reviewed the tear down videos enough to know my way around when the time comes.
      Last edited by designerron; 11-17-2021, 09:38 PM. Reason: Problem solved.


        CLICK, CLACK is back. I thought I had solved the problem by inserting a rubber pad between the motor and the frame and tightening the motor mount, but it returned after a couple of rides.

        I removed the rubber pad and found it had compressed from 1/8" to about 1/32". I looked around my garage for other sources of rubber and tried a few more things:

        The first pad, 1/8" dense foam, compressed too much and the sound gradually returned.

        The second, 1/16" rubber, was too thin, and the noise was back.

        The third, 1/4" dense foam (part of an old handle grip), compressed to easily and the click, clack sound was almost immediate as I rolled out the driveway. I think it allowed too much motor movement.

        The fourth was a 1/16" firm plumbing washer. I thought that would do the trick, but it didn't.

        Next I removed the motor to make sure the bottom bracket adapters were not loose. Luna press fit adapters were out of stock when I ordered my kit, so I bought them from Empowered Cycles. Theirs are a loose fit. I installed them with an aluminum shim and some Loctite for a tighter fit. The drive side fits flush with the bottom bracket, but the other side sticks out and I found I could turn it. Was this where I was getting motor motion?

        I applied a dab of expoxy to the adapter and shoved it back in, bolting the motor tight to the adapter and let the expoxy set. Then I assembled everything and used the rubber washer as a spacer. This seems to have stopped most of the noise. I still get some clicking, mostly when pedaling strong like up a hill but also randomly at other times. It's a big improvement.

        Does anyone else use a "rubber bumper" between the motor and the frame? I didn't have one for the first 2400 miles and all was quiet. Do I need a new motor mount plate that will have a better "bite" on the aluminum adapter? Any thoughts or ideas are appreciated.


          I am CERTAIN that I have found the cause of this problem on my bike. I have tracked the problem to the same cause on two different motors and during road trials of more than a year. I have developed a fix that is NOT elegant, but does work for several months at a time.
          The problem is caused by the flexible magnetic PAS disc that tells the controller when you are pedaling. It is mounted on a keyway on the main shaft, behind the pawls and large gear and just in front of the small thrust bearing. My theory is that the disc flexes a bit during pedaling and makes the snapping sound as it constantly repositions when it becomes a bit loose on the keyway. The noise is amplified by the plastic material that the disc is made of and can be clearly heard as quite loud clicking and clacking while pedaling. It can happen in any gear at most any power setting, but only while pedaling.
          Access the disc by removing the pedal arms both sides, then take off the chainring and large gear cover and remove the drive shaft. My fix should work if you can wiggle the disc back and forth against the keyway.
          The fix is achieved by tightly winding dental floss around the shaft into the tiny gap between the disk and the retainer. Do at least three revolutions of floss until the disc is tight and no longer moves back and forth against the keyway. Trim back the floss to the edge of the retainer.
          I foolishly forgot to take pictures when I recently fixed my second motor, but the PAS disc can be seen in this LunaCycle link:
          Distributors and builders of high power electric bikes and trail bikes plus parts


          • designerron
            designerron commented
            Editing a comment
            Interesting. There are numerous sources for strange noises and it's great that you found a cause and solution to yours. I'm the OP, and on mine I found the problem was the quick link on the 10 speed chain. The SRAM quick link was slightly longer than a standard chain link and when replaced with a KMC quick link the noise went away. I have another post about it somewhere around here.