Snapped allen bolt in carbon steerer expander bung

stybar15
stybar15 Posts: 3
in Workshop
Was trying to put in a new carbon expander bung as my old one was overly stiff. While doing this, the bolt snapped - as there was play in the headset even when the top cap bolt felt tight, so I probably over-tightened.

As it's a relatively delicate area, just wanted to know if anyone else has got a snapped bolt out with a screw extractor or gone to a bike shop to get one out?



I started drilling into it with a normal drill bit for a pilot hole then trying to reverse drill it with a screw extractor but not getting any purchase in it at all. Any ideas why that may be?

Comments

  • veronese68
    veronese68 Posts: 27,812
    The problem with the reverse screw extractors in something like that is that it is very easy to break them. If that happens you are screwed.
    How straight was your pilot hole? If you got it straight go progressively bigger with the drill until the bung falls apart.
    Kinesis Pro6
    Marin Nail Trail
    Cotic Solaris
  • stybar15
    stybar15 Posts: 3
    veronese68 said:

    The problem with the reverse screw extractors in something like that is that it is very easy to break them. If that happens you are screwed.
    How straight was your pilot hole? If you got it straight go progressively bigger with the drill until the bung falls apart.

    So you mean try and drill all the way through so the bolt becomes hollow down the middle?
  • lesfirth
    lesfirth Posts: 1,382
    Dont take this personally Stybar. We all have different skills in different areas but the fact you snapped the bolt suggests to me that you do not have the skill and expertise to sort this yourself. IMHO your best option is the LBS and hope they have the skill required.
  • veronese68
    veronese68 Posts: 27,812
    Start with that, if it doesn’t work sacrifice the bung and drill bigger than the bolt so the bung falls out.
    Kinesis Pro6
    Marin Nail Trail
    Cotic Solaris
  • thistle_
    thistle_ Posts: 7,218
    If you have a big enough freezer stick it in there?
    Apparently aluminium has a much bigger coefficient of thermal expansion than CF so it might shrink just enough for it to be able to be shaken out depending on how tight you actually did it.
    Not sure what happens if you have a big steel bolt in the middle of the aluminium, although steel should still shrink more than the CF.
  • stybar15
    stybar15 Posts: 3
    lesfirth said:

    Dont take this personally Stybar. We all have different skills in different areas but the fact you snapped the bolt suggests to me that you do not have the skill and expertise to sort this yourself. IMHO your best option is the LBS and hope they have the skill required.

    Yeah it was a stupid thing to do, I'll blame it on doing that while a bit underslept and hungover. On the other hand I did assemble this bike myself - I was one of those who got the Scott CR1 SL frame on the 75 % discount back in 2013, which kicked off the mother of all threads on this forum.
  • flasher
    flasher Posts: 1,734
    Think I'd be disassembling the bike first!

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