Pedal arm question

Mikey1976
Mikey1976 Posts: 165
edited May 2013 in Workshop
Hi People

I come back from a ride yesterday and noticed the arm is not flush with the bottom bracket area (see Pic)

All the bolts were tight so not sure why this had moved, ive re-set the pedal arm and its now flush.

Someone mentiond that this shouldnt of happened because there should be a circlip in place?

The chainset is a FSA if this makes any difference, has anyone ideas how this could of moved?

Cheers

Comments

  • rubertoe
    rubertoe Posts: 3,994
    I had this problem with an FSA chainset, it was down to the bolt coming loose - in the end the bolt come out on a ride and the pedal arm came off.

    Que trip to LBS and a new crank
    "If you always do what you've always done, you'll always get what you've always got."

    PX Kaffenback 2 = Work Horse
    B-Twin Alur 700 = Sundays and Hills
  • estampida
    estampida Posts: 1,008
    so the bolts might have been tight but:

    if the pinch bolts were tight then the axle was not pre-tensioned correctly on installation (slack on the drive side you cannot see)

    or when the cranks were last put on the bolts were tightened in the wrong order (oh dear)

    I have a set of fsa moto X cranks and I think the first ride ever they might have shifted a little but never have moved again

    I would take apart and clean the inside up and re-assemble properly, so you know its been done right and there is no dirt stuck in there only clean grease
  • Ben6899
    Ben6899 Posts: 9,686
    Clean it up and start again; it looks filthy.
    Ben

    Bikes: Donhou DSS4 Custom | Condor Italia RC | Gios Megalite | Dolan Preffisio | Giant Bowery '76
    Instagram: https://www.instagram.com/ben_h_ppcc/
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  • Ouija
    Ouija Posts: 1,386
    That can also happen if you didn't tighten up the pinch bolts the correct way. Simply tightening up one bolt until tight and then flipping to the other side and tightening up the other bolt gives the appearance that everything is fine but in fact it isn't as the way the pressure is being applied to the axle is incorrect, allowing it to work its way loose.

    Should always tighten up one bolt a quarter turn, then the other, then back to the first and so on, doing up each one in increments. As you tighten up one bolt a quarter turn, the opposing bolt should appear to slacken off slightly. However, don't use this as an excuse to turn it twice as far to compensate (stick to applying identical amounts of rotation to each bolt). The last thing you want is to have one finger of the pinch bolt moving more than the other (you want both fingers to meet up in the middle having moved the same distance and applying the same pressure, not one finger moving to meet the other and having a higher tension, if you see what i mean).
  • Mikey1976
    Mikey1976 Posts: 165
    Thanks for the info.

    Will have a closer look tonight...
  • keef66
    keef66 Posts: 13,123
    +2 to the advice to take it off, clean and grease the splines, and put it back together properly. Do you have access to the relevant FSA instructions including torque settings? (I'm a Shimano Hollowtech 2 user, and there's a plastic cap that screws finger tight into the NDS crank in order to preload the BB bearings before the pinch bolts are tightened)
  • Mikey1976
    Mikey1976 Posts: 165
    keef66 wrote:
    +2 to the advice to take it off, clean and grease the splines, and put it back together properly. Do you have access to the relevant FSA instructions including torque settings? (I'm a Shimano Hollowtech 2 user, and there's a plastic cap that screws finger tight into the NDS crank in order to preload the BB bearings before the pinch bolts are tightened)

    Yeah I have 2 pinch bolts and a plastic cap that screws in.

    So would I tighten the pinch bolts first, obviously each one turn by turn, and then tighten the center cap last?
  • Ben6899
    Ben6899 Posts: 9,686
    Mikey1976 wrote:
    keef66 wrote:
    +2 to the advice to take it off, clean and grease the splines, and put it back together properly. Do you have access to the relevant FSA instructions including torque settings? (I'm a Shimano Hollowtech 2 user, and there's a plastic cap that screws finger tight into the NDS crank in order to preload the BB bearings before the pinch bolts are tightened)

    Yeah I have 2 pinch bolts and a plastic cap that screws in.

    So would I tighten the pinch bolts first, obviously each one turn by turn, and then tighten the center cap last?

    No. The plastic cap "screws finger tight into the NDS crank in order to preload the BB bearings before the pinch bolts are tightened".
    Ben

    Bikes: Donhou DSS4 Custom | Condor Italia RC | Gios Megalite | Dolan Preffisio | Giant Bowery '76
    Instagram: https://www.instagram.com/ben_h_ppcc/
    Flickr: https://www.flickr.com/photos/143173475@N05/
  • Mikey1976
    Mikey1976 Posts: 165
    Ben6899 wrote:
    Mikey1976 wrote:
    keef66 wrote:
    +2 to the advice to take it off, clean and grease the splines, and put it back together properly. Do you have access to the relevant FSA instructions including torque settings? (I'm a Shimano Hollowtech 2 user, and there's a plastic cap that screws finger tight into the NDS crank in order to preload the BB bearings before the pinch bolts are tightened)

    Yeah I have 2 pinch bolts and a plastic cap that screws in.

    So would I tighten the pinch bolts first, obviously each one turn by turn, and then tighten the center cap last?

    No. The plastic cap "screws finger tight into the NDS crank in order to preload the BB bearings before the pinch bolts are tightened".

    Apologies, missed that.