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Clunk in front suspension

Discussion in 'Technical and Troubleshooting Torque' started by cuvy, Feb 2, 2006.

  1. Hi Guys,

    I've got a bit of a clunk in my forks when i brake heavily.

    It only happens under heavy braking, and if i grab the lever suddenly, it clunks then, and also once the fork rebounds up. if i clamp the front brake on when still, and compress the forks hard, it does clunk at the bottom (don't think i'm bottoming out the forks)

    So i guess it's either the head bearings are a little loose, or maybe the fork oil needs replacing (maybe with a heavier weight?). I don't have a jack to lift the front end up, so i can't easily test the bearing idea.

    Anyone have any ideas or advice?

  2. That's what I was thinking. :)
  3. if it were head bearings wouldnt you feel it in steering ? theres no oil loss is there ? could be a fork seal if there is
  4. Certainly sounds like head bearings. Do you hear or feel the clunk?

    Check anything that could be loose and work back from there.

    Use the old push bike approach of sitting on the bike with the front brake on hard and rocking the bike back and forwards. then get someone to feel for movement in the head bearings, fork sliders and brakes.
  5. As everyone has said... head bearings... sounds like what i had on my bike before the service...
  6. Do you have a centre stand?

    If so, put the bike on the centre stand, then have someone weight the back of the bike down. The front will come up and allow you to feel the head bearings.
  7. Check the triple-clamp bolts first...all there/ all firm? On both clamps?

    As mentioned above...headbearings COULD be the culprit.
    With someone else holding the bike upright, grab the bottom of the forklegs and jerk them firmly/ quickly back and forth.
    Any clunks/ hits noticable? (either via feel or noise?)
    If not, the headbearings should be fine.

    Front axle and clamp-bolts firm?

    Let's presume the clunking doesn't come from forks that bottom out...
    which leaves the brake-discs next.
    Floating discs? (the ones where rotor and carrier are rivetted together)?
    Grab one rotor at a time and try to rotate it against the carrier...get a clunk? Bit of movement?
    If yes, there's your noise...and nothing wrong with it.
    If the rotor moves VERY loosely against the carrier (nearly no force needed at all), then the rivets (buttons) are too sloppy. They can be re-buttoned by places like Awesome Discs etc. for fairly little $$.
  8. Doesn't sound like head bearings to me, that shows itself more when turning the bars side to side, or with a little bit of forward/backward movement of the forks I think.

    I've got the same thing happening at the moment on the Hornet and a few people have pointed to the fork springs being buggered. Not surprising given the abundance of crap and medium wheelies the poor things have put up with in the last couple of months.

    It feels as if there's a point halfway down the fork to max compression where something sort of goes 'clunk' and it interrupts the smooth compression fo the forks. It usually happens at the same spot in the compression, and you can make it happen by putting the front brakes on and pumping the forks while stopped.

    Get thee to a mechanic and look at some new springs. I'll be doing the same when I've got some money together - although it's sort of reduced a bit lately and isn't really giving me much trouble.
  9. Can I join the crap-wheelie squad? Scumbag can vouch for me after last Fridays coffee night home-run (on the postie) :LOL: :LOL: :LOL:
    Actually...don't bother, will start the "Crap Flying Squad" as the little CT110 had BOTH feet off the deck at some stage (was surprised myself as the engine spun to where ever redline might be, then semi bogged the autoclutch on touchdown).
    :cool: :cool:
  10. Are you kidding? You *invented* the crap wheelie!

    Now THAT's the spirit! The first day I had the hornet I had it accidentally airborne over a rail-crossing with Cheng on the back. Probably only a foot up in the air but jeeez I got some bruised kidneys out of it!

    /laughing maniacally at desk...
  11. Hi Guys,

    Thanks for all the replies.

    I don't have a centre stand, but i'll see if i can jack up the bike somehow. Tried half-arsedly last night but didn't have any luck.

    Loz, that does sort of sound like mine, it sometimes clunks near the top on the rebound. i'll have a bit more of a play around with it.

    Glitch_oz, thanks very much, i'll give all of those things a try.

  12. Cuvy,

    Had a similar clunk on my 2000 CBR600F in January, sitting on the bike with the front brake held on and rocking back and forth through the front suspension to find that damn clunk! As suggested wisely above, I hauled the bike onto the centrestand with someone weighting the back to get the front wheel off the gorund, and sure enough, as I swung the bars left to right gently, the head stem bearings dropped into a notch through each sweep.

    I had new headstem bearings installed last fortnight at the 18,000 service and the problem is fixed.

    No centrestand? OK, still need a friend or two to help, and once on the sidestand, continue carefully to pull the bike over on the sidestand until one of the two wheeels lifts slowly off the ground. Once you know which wheel wants to lift off first (typically the back one, dammit), go back to the start and then try again to pull the bike over on the sidestand but this time with weight on the back to make the front wheel rise. Definitely a job for two people to avoid an accidental tip-over.

    Then gently swing the bars through their normal steering sweep and see if they feel notchy or settle into a 'hole' through the sweep. If they swing smoothly uninterrupted through the sweep then the bearings SHOULD be OK but otherwise could still be loose (not so expensive to fix/adjust). Otherwise sorry, I'm out of ideas but read above and below for some good tips.

    Good luck!