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BBSHD 73mm problem: rotating like a pendulum, 2.0

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    BBSHD 73mm problem: rotating like a pendulum, 2.0

    This topic was closed for some reason, but the issue is not resolved.

    There has been some talking past each other.

    There are two considerations for my particular mounting problem:

    1. I need to put the spacer on the non-drive side in order to get an acceptable chain line.
    2. With no spacer on the drive side, on the 73mm unit the studs that the fixing bolts thread into stick out further than the face of the BB. Therefore spacers have to go between the fixing plate and the BB shell.

    Louis is right that " Properly installed the fixing plate is against the BB". I hope everyone can understand why "Putting the spacer on the outside of the fixing plate IS needed on some builds to take up the 5mm excess. (Louis)" doesn't work.

    I simple fix, which I have not found yet, is a 5 mm serrated spacer that would mimic the serrations of the fixing plate.

    #2
    OK, it is on the inside. That's an important bit of info. That makes it harder, sure.

    Serrations are hard to make. But I guess you could file a spacer to have a couple of trapezoidal teeth, and file corresponding notches into the frame. Finicky work fitting it though.

    I'd dare to try an adhesive first, even though it probably won't work. JB Weld or Plastic Steel or maybe bearing retainer? Roughen the surfaces and degrease well.
    Last edited by JPLabs; 06-11-2016, 06:14 PM.
    Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

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      #3
      Fastenal has lock washers that are serrated on both sides. Do you have a picture you can share. What is the actual bb size?

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        #4
        I just addressed mine yesterday - I didn't drill and pin the spacer under the plate (which I still think is the best and easiest solution) due purely to laziness - I simply re-torqued the spanner nut against the plate (and it was loose), though I doubt I'm up to the specified torque - those bike spanner tools are too short and too f'n hard to grab to apply the specified 60ft-lbs (or whatever its supposed to be). I did my best, then reinforced the motor/frame connection by wrapping it with a couple of big black zip ties - good enough for now and the ties aren't overly noticeable. Set a new land-speed record too, by an additional 1% - 40.5MPH - downhill at full throttle and no pedaling. I can't wait to get my extra 5A.
        Last edited by JayC; 06-12-2016, 07:09 AM.

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          #5
          I had to retighten my BBSHD yesterday, having gotten a lttle slop down there, the first time since I retightened it about 300 miles of rough trail riding ago. I have the proper tool to engage the nut, and I use a 24" pipe wrench on the tool, so a fair bit of leverage, so pretty darn tight, at least 60 lbs.

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            #6
            50 N/m is about 37 lbs/ft
            25 N/m about 15 lbs/ft.
            Just so people don't over tighten the nut, turns into a mess to fix if you do.

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              #7
              I'm over torquing for sure, by now. Had a creak over the weekend, the teeth had moved the BB metal so the motor was moving a little. Only about 1 mm. So I stood on my wrench this time for the first nut. That's something over 100 Ft lbs. Dry, not lubed.

              I think published BB torques are not enough for this application.

              My cut threads on the Bafang are rough/chattery, so clamp load is lower than it would be with finely cut threads. If you have nice smooth threads, less torque should work.
              Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

              Comment


                #8
                Originally posted by Mgbguy1 View Post
                Fastenal has lock washers that are serrated on both sides. Do you have a picture you can share. What is the actual bb size?
                Hey Mgbguy, can you give me a link? I couldn't find such a washer at Fastenal.

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                  #9
                  Originally posted by CPG View Post
                  I had to retighten my BBSHD yesterday, having gotten a lttle slop down there, the first time since I retightened it about 300 miles of rough trail riding ago. I have the proper tool to engage the nut, and I use a 24" pipe wrench on the tool, so a fair bit of leverage, so pretty darn tight, at least 60 lbs.
                  Thanks, CPG! The pipe wrench was a good idea! My lock ring tool was also too short, but the pipe wrench provided plenty of leverage and gripped the lock ring directly very well. I tightened it much tighter and now, NO MORE PENDULUM! All is well.

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                    #10
                    Jeebus, a pipe wrench, careful boys. One slip with a pipe wrench and you'll have a scared up mess. Don't forget that blue loctite. I like double primary lockrings instead of a spacer on 68-73mm kits fitted to a 68mm BB.

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                      #11
                      I've read additional reports of some rotating problems and especially on builds where having spacers inside the the fixing plate makes for a better build. I have it on good authority a solution is being tested and will soon be available. The BBSHD has created more stir and solutions at much faster rates than the BBS02. Exciting times.

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                        #12
                        Any update on this mythical solution? What it is, how much it will cost, when it will be available?

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                          #13
                          I'll check with the Centaur and post as soon as I hear back.

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                            #14
                            I was pleased that Luna remembered my complaints and sent me an extra triangle serrated mounting plate with the tongues cut off. This amounted to a serrated spacer and using it, it solved my pendulum problem (which had returned after I had thought I had solved it by tightening with a pipe wrench.) I think that a second lock nut makes a lot of sense and be the best. The thin one that comes with the unit is not the most effective.

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                            • JPLabs
                              JPLabs commented
                              Editing a comment
                              Clever solution, and good to hear.

                            #15
                            Originally posted by Stu Summer View Post
                            I think that a second lock nut makes a lot of sense and be the best.
                            Originally the design was with two of the primary locknuts now in the kit. The Cap style locknut was an "improvement".

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