pizzapie.. Posted August 16, 2009 Report Share Posted August 16, 2009 Hello, i have got some echo cnc 7057 cranks with tensile free wheel and echo bash, and have fitted them onto a fsa bottom bracket, but i tighten the cranks and they come loose, and the left crank arm (non drive side) you can atcherly wobble it from side to side and is loose even when i have tighten it as tight as it will do i was wondering if it is cranks or my bb that need replacing? Thanks liam . Quote Link to comment Share on other sites More sharing options...
Matt Burrows Posted August 16, 2009 Report Share Posted August 16, 2009 BB axles are made from hardened steel, cranks are made from comparitively soft aluminium. If the crank bolts aren't done to the correct torque and the bike is ridden with them loose, it squashes the soft alu crank taper. Making for loose fitting cranks that will keep coming loose, even after the bolts are done up really tight. Quote Link to comment Share on other sites More sharing options...
pizzapie.. Posted August 16, 2009 Author Report Share Posted August 16, 2009 BB axles are made from hardened steel, cranks are made from comparitively soft aluminium. If the crank bolts aren't done to the correct torque and the bike is ridden with them loose, it squashes the soft alu crank taper. Making for loose fitting cranks that will keep coming loose, even after the bolts are done up really tight.So i need new cranks? Quote Link to comment Share on other sites More sharing options...
idlehans Posted August 17, 2009 Report Share Posted August 17, 2009 (edited) So i need new cranks?Hiya pizzapie,matt's right about your crank problem.I'm a cycle mechanic and i've seen this a million times.It sounds like they are rounded off slightly and there is no way of fixing it other than getting new cranks i'm afraid.Make sure you torque them up correctly and check them once in a while.You should really check them before each ride but no one really does.Don't forget to put a little grease on the tapers.Hope this helps you out.byeeeeeeSorry,I should have mentioned that you can probably buy just a left hand crank to replace your damaged one. Edited August 17, 2009 by idlehans Quote Link to comment Share on other sites More sharing options...
MAX (M.A.D) Posted August 17, 2009 Report Share Posted August 17, 2009 I don't no if this will work the same but on my mountain bike i have a square tapered bb and the cranks rounded of and kept comming loose so i put some duck tape around the bb axel where the cranks fir on and they havn't come loose since. It would be worth a try to put some around your isis bb axle and see what happens. Max. Quote Link to comment Share on other sites More sharing options...
pizzapie.. Posted August 17, 2009 Author Report Share Posted August 17, 2009 I don't no if this will work the same but on my mountain bike i have a square tapered bb and the cranks rounded of and kept comming loose so i put some duck tape around the bb axel where the cranks fir on and they havn't come loose since. It would be worth a try to put some around your isis bb axle and see what happens. Max.tryed that, did'nt work, thank you every one for your answers thank you so much all been a real help. Quote Link to comment Share on other sites More sharing options...
Jamie905 Posted August 17, 2009 Report Share Posted August 17, 2009 Back in my BMX days I had some Primo Hollowbite's which were the same square taper design as trials ones, except buying them second hand, one of the tapers was slightly rounded.I cut up a bit of a Coke can and placed it around the taper to act as a shim. Its a bit of a pain and a bodge, and it's a shit to get on, but it worked for me Quote Link to comment Share on other sites More sharing options...
Dale-Hill Posted August 17, 2009 Report Share Posted August 17, 2009 I don't no if this will work the same but on my mountain bike i have a square tapered bb and the cranks rounded of and kept comming loose so i put some duck tape around the bb axel where the cranks fir on and they havn't come loose since. It would be worth a try to put some around your isis bb axle and see what happens. Max.Or use a thick plastic bag That's what i did on my echo forged Works a charm Quote Link to comment Share on other sites More sharing options...
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