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BBSHD movement after install

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    BBSHD movement after install

    So I posted this in my build thread, but thought I would put something here to help get some input. I started seeing movement in the motor, not in the axle but rather the motor housing itself, up and down. Figured I didn't tighten it down well enough, or the bolts and lock ring became loose, so I tightened everything down. Still movement. Took the lock ring and mounting bracket off and this is what I found.





    Basically the movement was from the motor torque, I am guessing, and created some nasty grooves on my frame. My concern is that this is a steel frame and I do not want rust to form, plus now no matter how hard I crank, the teeth on the bracket wont grab well in those grooves. I have seen the use of Epoxy Putty and heard about hose clamps to stop movement, but wondering if I should grind this down to get the teeth of the bracket to grab again? What should I do to rustproof this area now? I am in Seattle, so avoiding rain is a lost cause.

    #2
    The best rust proofing that I ran across in the automotive industry called zinc dust. Mercedes Benz carried it but it was stupid expensive. It is basically ground up Zinc in a clear lacquer. It was like paint on galvanize, great for small jobs. Maybe there is an equivalent available.

    Look up "Cold Galvanized Paint" yeah it is still stupid expensive and all you would need is a touch up bottle size.
    Last edited by calfee20; 08-30-2016, 04:00 PM.

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      #3
      ACF50 works for airframes I use it all over my rides. Each connection gets a bit and all points of potential rust/corrosion as well. After a good prep and paint touchup it makes a great treatment and lasts for months. There are other brands but Beoshiled and ACF50 seem to be the best available. There are some others but their cost is prohibitive as they're not available in small quantities.
      Last edited by Louis; 08-31-2016, 09:27 AM.

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        #4
        ACF50 is good one time treatment (don't do before painting though) for aircraft internal skin protection. But for floatplanes in salt water, we use this for moving parts and joints. Very effective, cheap, and can be found in many hardware stores.
        http://www.fluid-film.com/

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        • Louis
          Louis commented
          Editing a comment
          Can it be used on electrical connections too? Also can you explain why you say ACF50 a one time treatment? I worked well on my sailboat mast in the Caribbean. The pintles and gudgeons were also subject to corrosion in the salt water and ASF did the job. Interesting that the Fluid Film is lanolin based. Does it dry to a hard film? Always good to learn new things! Thanks!

        #5
        The torque reaction from the motor drives it up and into the downtube. It is important that it have some support there, and that it not start moving even a little bit. I did the epoxy putty conformal gasket because my frame was alloy and I didn't want that force concentrated on a small spot, steel is stronger but it might be much thinner at that point where the motor touches it. You didn't show that spot in your photo, did the motor contact the downtube and do damage there?

        Looking at the BB shell, I wonder if the proper torque values were used. That BBSHD appears to have been overtorqued, I would not expect that level of damage to the steel bottom bracket shell. Over torquing deforms the materials and causes other problems.

        I see some builds that use a rubber bumper between the motor and downtube. I think this is a bad idea because it promotes motion, and once you have a little it develops into a lot. I'd like to see the motor's torque taken directly by the downtube with zero motion, and the BB shell's role is only to hold the motor against the downtube. The epoxy putty I used is for the conformal gasket is quite rigid, and serves to spread the forces out over an area of the motor casing and downtube. It is probably overkill, but I've seen photos of what happens when a drive gets loose and pounds a hole into the downtube, so I was responding to that.

        Even though I tightened and loctited the BB shell nuts holding the BBSHD, the drive still loosened slightly, so I retightened them once. Talking to a dealer who has installed hundreds of BBS02's he indicated that it is pretty much always necessary to retorque once after things settle in with some riding.

        Good luck sorting out your problems.
        Alan B

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          #6
          ACF50 is a major effort to treat all the external skins of an aircraft (I have used it), and usually lasts a long time. I am just saying that it is a good one time treatment, not that you can't do it more often. Fluid film is also a lubricant. Be sure to wipe off the excess, though, as it will attract dirt, too. But it certainly is very good at protecting moving parts and joints against corrosion. And no, it does not dry to a hard paste. But I would guess that it would be very good at keeping a BB corrosion free (and lubricated). Not sure about electrical connections.

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            #7
            I should have a link soon to a "torque arm" for BBS series motors. Still waiting....

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