Fitting non drive side crank arm

jdee84
jdee84 Posts: 291
in Workshop
Last week my shimano 105 (7000) non drive side crank arm came off while out on the bike. The head of the bolt which screws the crank into the bottom bracket area was cracked. I've got a new bolt and fitted the crank arm again, the crank arm would only sit on the axle when i tried to push it on. Only when i started to screw the new bolt into the axle would the crank arm go on the axle more securely. The crank arm is now sitting pretty flush to the Shimano BB-R60 Threaded BSA should that be the case or should there be a bit of a gap of 5mm or so between the crank arm and the BB?

Comments

  • whyamihere
    whyamihere Posts: 7,716
    edited November 2021
    EDIT: I misread the post first time. That sounds fine, a picture would help to check it though.
  • masjer
    masjer Posts: 2,693
    edited November 2021
    There should be no gap between the crank arm and BB. The crank arm should provide a slight preload on the BB bearing.
    The resistance you are feeling installing the arm might be because the splines have been slightly damaged/deformed when the crank arm was loose and ultimately fell off.
    Grease the splines and pinch bolts before installing.
    Make sure when you tighten the 2 pinch bolts up (12-14NM) they are done up in an incremental (i.e half turns), alternating manner.
  • jdee84
    jdee84 Posts: 291
    thanks for the responses, i had greased things up before installing and done the bolts tightening in increments. Just wasn't sure if it should sit flush as i was sure there had previously been a gap but that must have been from a bad service at a LBS at the start of autumn

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