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BBSHD Crank bolt killin me

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    BBSHD Crank bolt killin me

    Anyone have any trouble keeping the non-drive side crank tight.....I have been using Loctite and a torque wrench but still loosens up after every ride.....short rides < than a couple miles. New crank arm? Will a lock washer under the crank bolt do anything? I submitted a ticket on Luna C. but still having trouble. Anyone use the RED Loctite? I was warned not to use this...not sure what else to try.

    #2
    Do you pedal significantly? I've never met a Loctite that some heat wouldn't loosen. I'd go for the Red if nothing else is working.

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      #3
      This kept happening to me as well. Blue Loctite and proper torque didn't seem to help and I was having to tighten it up after every ride so I finally gave it some red Loctite and it hasn't moved since. I figure I can get it off later with a long lever and my heat-gun...

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        #4
        Once mine loosened the first time, I never got it tight again, either. So I think the pedal must have deformed a little. I picked up some unicycle cranks to use instead.

        Good to hear Red might do the trick, too. That would be real handy to know.

        Yes, heat will soften the Red Locktite, too. If you do need to do that:

        I'd be a little worried the crank could get hot, and wreck the rubber bearing seals. Best to use a lot of heat, fast, and stop as soon as the locktite is softened. Like a propane torch for 10 seconds or whatever, instead of a heat gun for 5 min. Less time for heat to soak into the adjoining parts. A wet rag over the crank could help keep it cool. Then air or water to cool it faster once the arm comes off. Just to be prudent and minimize any cooking of those rubber seals.
        Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

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          #5
          If you need to heat Loctite bolts in sensitive areas like the BBSXX with O rings nearby, I'd try a soldering iron with a fat tip. Preferably a hammerhead tip which also comes in real handy for pouch cell battery tabs, large power connectors, 10-12ga wire, etc.

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            #6
            The supplied bafang cranks are noodly soft, I also replaced them with unicycle cranks very early on. No loosening issues.

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              #7
              Originally posted by lairpost View Post
              The supplied bafang cranks are noodly soft, I also replaced them with unicycle cranks very early on. No loosening issues.
              Link to those cranks?

              Comment


                #8
                Sunlite Crankset Unicycle 6In Front 24 in

                Just ordered mine, Don't know if these will be the fix or not.

                Bafang crank arms failed first major ride.

                Bought $55 Schlumpf arms and they had the same problem getting loose.

                Finally removed the paint from the Bafang crankshaft. Blue Loctite. Crank arms stayed put then.

                Then the pedals stripped out their holes this week just like on the original Bafang crank arms.

                It makes me feel like some sort of Superman but honestly my legs aren't that strong.

                Anyhow, the Sunlte Crankset I listed was the cheapest solution and bonus: made of steel.

                Unhappy about the excess weight but if it is durable I'll get some miles done. So far - two trips into town and a bunch of rides around the neighborhood. ~150 miles.

                Also fighting dead chargers. Am on my third charger but Lunacycle has taken care of me very well. First DOA when I built the kit, second failed after several charges. Now have their advanced charger and it is charging for the first time.
                Last edited by joeaverage; 07-13-2017, 07:36 PM.

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                  #9
                  http://www.ebay.com/bhp/self-extracting-crank-bolts

                  Comment


                    #10
                    Right, it is the paint that is the problem. Once removed, the cranks will stay put. Mine did, after many re-tightenings at the beginning, until the pait wore off. Never moved again after that. However, if you let them get loose, you will damage them, and then it is too late. Best to strip the paint inside the opening and off the axel first, then i stall them. You may still need to re-torque them a few times. Once settled, remove bolts, put locktite, reinstall, forget ...

                    Best to get the Shimano STePS replacement ebike crank arms for about $30 off eBay and other sources. Much sturdier than stock Bafang arms which were twisting on me under hard pedal power. Very happy with the Shimano cranks. See recent threads on that.

                    Comment


                      #11
                      Originally posted by Kocho View Post
                      Right, it is the paint that is the problem. Once removed, the cranks will stay put. Mine did, after many re-tightenings at the beginning, until the pait wore off. Never moved again after that. However, if you let them get loose, you will damage them, and then it is too late. Best to strip the paint inside the opening and off the axel first, then i stall them. You may still need to re-torque them a few times. Once settled, remove bolts, put locktite, reinstall, forget ...

                      Best to get the Shimano STePS replacement ebike crank arms for about $30 off eBay and other sources. Much sturdier than stock Bafang arms which were twisting on me under hard pedal power. Very happy with the Shimano cranks. See recent threads on that.
                      How did you strip the paint? Did you find an easy way which doesn't damage the aluminum, or just scrape and sand as usual.

                      I may as well do that next time I have them off...
                      Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

                      Comment


                        #12
                        While I thought about sanding off the paint, I was lazy and just installed them. I think the paint stripped itself due to multiple retightenings, several times per ride,every few miles initially. On my kit there was paint on the axel and on the cranks' holes.

                        Basically, rode with the the hex wrench handy and just stopped every once in a while and torqued them down each time by a quarter or so turn. Eventually, it was gone and the cranks stayed put. I don't think this is a good way to do it, but it worked, because I did not let the cranks get loose around the axel at any point (if you do, you will round the square and you'll have to get new cranks).
                        Last edited by Kocho; 09-21-2017, 02:02 PM.

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                        • JPLabs
                          JPLabs commented
                          Editing a comment
                          OK, I'd say that's an easy way, best of all I'm doing it already.

                          Thanks.

                        #13
                        http://www.ebikeoutpost.com/products...nt=31060023305

                        Comment


                        • JPLabs
                          JPLabs commented
                          Editing a comment
                          Thanks for the link!

                        #14
                        Probably regret it but 'stumbled on these 114mm alloy unicycle square taper cranks - http://www.ebay.com/itm/QX-AX-1-Unic...72.m2749.l2649

                        At minimum will improve pedal strike clearance. And if lucky 'might even "feel" a tad more resistance at higher road speeds? Or, I might've just wasted $26....???

                        Comment


                          #15
                          I'd be curious to find out how you like them. I personally like longer cranks for two reasons: first, I can actually put some torque down to help move the bike (especially if I run out of battery); second, I got big feet, and if the cranks are too short, my knee will be way forward of my toes, which tends to cause knee pain for me on a bike.

                          But for just maintaining cadence, they should be great.

                          Originally posted by ykick View Post
                          Probably regret it but 'stumbled on these 114mm alloy unicycle square taper cranks - http://www.ebay.com/itm/QX-AX-1-Unic...72.m2749.l2649

                          At minimum will improve pedal strike clearance. And if lucky 'might even "feel" a tad more resistance at higher road speeds? Or, I might've just wasted $26....???

                          Comment


                          • ykick
                            ykick commented
                            Editing a comment
                            Definitely weird but the more I ride with them the less weird they feel. LOVE the cornering clearance! I don't think the old fatty can strike a pedal anymore.

                          • Kocho
                            Kocho commented
                            Editing a comment
                            I think they work well for you since you like to ride with the seat relatively low (at least compared to me). If I shorten my crank by 70mm, I would need to raise my seat by about as much in order to maintain good leg extension. Which would put me too high above the ground, and I already barely reach the ground as it is, plus it would force me to lean more forward than I like as my handlebars won't go any higher.
                            Last edited by Kocho; 09-23-2017, 04:42 PM.

                          • ykick
                            ykick commented
                            Editing a comment
                            Funny you mentioned seat height because I actually raised it a bit since my legs don’t need to extend as much using the 114mm arms. Still low enough I don’t get out of the saddle at stops but now high enough so that I can use a seat post luggage rack.

                            Took a long ride today and really enjoyed the extra cornering clearance while pedaling. Big improvement leaving PAS working while leaning significantly into curves

                            It’s also nice to “feel” a tad more resistance with the short stroking crank arms. Especially around 25 MPH.

                            Still kinda weird but in a good way….
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