Bolt Self Loosening - Advice Please

Discussion in 'Technical Help' started by Robarano, May 30, 2016.

  1. One of the bolts on my quickshifter keeps self loosening.

    So far -
    • It's happened every time I've had a day on the bike.
    • I've torqued it up as much as I dare
    • Used a medium strength threadlock
    I do need to remove this bolt to get the gear lever off, so a premanent threadlocker is out of the question. Loctite 276 has a break away force of 60nm but is bloody expensive. Is this the way to go?

    So some advice please on stopping this happening. Has anybody had something simlar happen and found a solution?

    Screen Shot 2016-05-30 at 09.45.jpg
     
  2. What does it screw into? Can you use longer bolt with a locknut at the back?
     
    • Agree Agree x 2
  3. I don't think so Derek. I had a quick feel around the back and didn't feel a hole (ooo, err missus ! :)). I'll have a better look today.
     
  4. Try using silicone sealer on the threads. It will come undone easily enough but because it is soft it seems to absorb vibration and not loosen up and of course it cleans off easily enough as you can dip the bolt in petrol or some other solvent like thinner to clean it.

    I have used this method a lot on rearsets and associated bolts that hold them to the frame and it has always worked for me.
     
    • Useful Useful x 1
  5. It's not vibration that is loosening it. It's the force of kicking the lever up and down. No other bolt on the bike is doing this,
     
  6. If there is room, maybe drill a hole thru the back for a lock nut
     
    • Agree Agree x 1
  7. Drill a 1mm hole through the head of the bolt - right across so that it actually is two holes with the socket between them.

    Then drill a 1mm hole at 45 degrees through the corner of the lever - about 4mm down, say - just before the carbon guard.

    Then lockwire it.

    Screen Shot 2016-05-30 at 09.45 copy.jpg
     
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  8. Spring washer?
     
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  9. Internally toothed lockwasher?
     
    • Useful Useful x 1
  10. I've never had a threadlock solution fail once it has been allowed to dry off. Is the thread clean before you use threadlock and are you allowing sufficient time for it to dry?
     
  11. Clearly something is not right then if the bolt is coming loose.
    Are the mating parts square and parallel to each other?If not then tightening the bolt is only making the problem worse!
    The bolt is only a clamping fastener and if it comes loose then there is a problem. Fact.
    Think of how many fasteners are in your engine?
     
  12. Why not just wire lock it - simple and shakeproof.
     
  13. Is the body of this screw a pivot for the QS action?
     
  14. It is old Steve, but not ridiculously so.

    I had to take the footrests and steering damper off the other day, both of which were assembled with the same Loctite and I could tell it was in there.

    I'll pull the QS apart and check there is nothing amiss. Then reassemble with stronger threadlock and see how that goes.

    Oh, and I've checked behind the gear shifter. No space for a lock nut either.
     
    • Like Like x 1
  15. Nord-Lock washers are the best by far. When you undo them they actually have to tighten up slightly to camover before they undo...this will never happen due to vibration, they will never vibrate loose in you application.
    However they will not work on hardened steel surfaces because the back face of the washer needs to bite in.
     
  16. Cheers, I'll give these a go.

    Again, the problem isn't down to vibration though. When I knock the gear lever up, I'm managing to loosen the bolt over the course of a few hours due to this action rotating the bolt anti-clockwise.
     
    • Useful Useful x 1
  17. There are bolts with a silicone key like insert that lock the thread. Look for those.
     
  18. Thanks @Sev

    It sounds like a lot of work and I'm not sure it would be effective as the quickshifter works both ways and the action of kicking the lever down would have the same effect that kicking it up currently does. Plus it is a blind hole, so having to tap with a LH thread etc......

    I'm going to have a look at it today. I've bought some Scnorr washers and upgraded thread lock. I'll try this ist.
     
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