Fork bung problem

wjperrin
wjperrin Posts: 97
edited June 2013 in Workshop
Hi there, I'm using a Planet X pro carbon fork with the specific PX fork bung. I have installed it correctly but over time I start to to get play in the headset. More so during a crit when using the front break alot. Anyone have any tips to solve this? Would carbon compound work? I'm presuming its the bung that is coming loose.

Thanks

Comments

  • night_porter
    night_porter Posts: 888
    This is strange because the bung is only there for pre-tensioning the headset and once you have tightened the stem bolts the top cap could actually be removed and bung becomes redundant.

    I would check the bolts in the stem if I was you because if they are loose then your headset will have play.

    Alternatively it could be a faulty headset?
  • wjperrin
    wjperrin Posts: 97
    I have just had another look. I have swapped the spacer ontop of the stem for a slightly thicker one. Hopefully it will pull it down a bit more now. Will try it out this evening. Thanks
  • nicklouse
    nicklouse Posts: 50,675
    you will not have tightened the stem enough or the bearings are wearing out.

    the top cap can be removed after the stem has been tightened correctly (in practice it is best not to).
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • wjperrin
    wjperrin Posts: 97
    I have tightened the pinch bolts to the correct torque. I will put some loctite on them and see how it goes.

    Thanks
  • sungod
    sungod Posts: 16,606
    as above, once you've set the preload with the top bolt it's the stem that's responsible for holding everything in place, not the bung/top cap - assuming the headet is all ok, and the crown race was fully seated on the steerer...

    degrease the steerer and stem in the clamping area, then put some carbon assembly paste on before clamping
    my bike - faster than god's and twice as shiny
  • night_porter
    night_porter Posts: 888
    wjperrin wrote:
    I have just had another look. I have swapped the spacer ontop of the stem for a slightly thicker one. Hopefully it will pull it down a bit more now. Will try it out this evening. Thanks

    If I am reading this comment correctly it sounds like you didn't have enough of a gap between the top of the fork and the spacers to be able to set the pre-load. If this is true then increasing the size of the spacer will do it.

    If it was pre-loaded sufficiently but it has "worked" loose then the stem bolts are at fault. Is the a gap at the back of the stem where the bolts clamp it together? If not then the stem is the wrong size and if there is then that is how it should be and it just needs tightening correctly.

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