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No drive - in gear, bike freewheels, chain ok...

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by AngryAnt, Feb 1, 2012.

  1. Writing this from the side of the Monash freeway... Cruising along happily in 5th at about 90km/h when bike starts to slow. In gear - check. Engine running - check. Revs visible in tacho - check. Any power? None. Pull over, luckily I was in the second from left lane. Other symptoms... Bike freewheels when in gear. Chain is good. Wondering whether the front sprocket has come loose as I had problems with a dodgy nut on that shaft a while back which I replaced. Tow called, will report back later. Bike is a '98 Zeal, FZX250....



    Tappin' not talkin'


     
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  2. worn clutch?
    could be sprocket, but i would think there'd be some kind of displeasing grinding noise and a chain dragging on the road
     
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  3. What a bugger! The engine runs right, but just no power getting transmitted... sounds like a clutch issue. You should have noted some slippage as an early symptom though... hope it's not a total disaster!
     
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  4. No such symptoms.. No nasty grindy noises a la sprocket/ chain, but no clutch symptoms leading up either... Clutch cable and action where cable meets clutch housing seems normal. Anyway, on the way home with towie now. Will report diagnosis as it comes in.

    Tappin' not talkin'
     
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  5. main thing's you're ok Anto!! hope it isnt too costly to fix.
     
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  6. Sounds like clutch or else there would be a lot of grinding noises.

    Clutch cable stuck or something? <----sounds stupid but anything can happen!
     
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  7. no... clutch cable and action seems fine. Could be INSIDE the clutch though where I can't see. Anyway, home now so all ok...
     
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  8. I've had sprocket nuts come off and the gear slides across onto the thread so no power to the wheel, no strange noises.
    Also had a clutch basket come loose, that was noisy..
     
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  9. Have had a stripped driveshaft before, same symptoms, big job if that's the case
     
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  10. Yeah, this was the case. This is a replacement sprocket nut so the threads must be cactus now. So looks like a new countershaft! Wonder how big a job that is.
     
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  11. Big. But you should confirm that before trying anything below, which are aimed at not having to remove the shaft from the engine. If you have to remove the shaft, you may as well have is properly repaired, or replaced.On some engines it isn't all that hard or expensive. On others it requires a virtual engine rebuild.

    If you find the right repairer, they might be able to build up the thread area and re-cut the thread. While those nuts are typically torqued up pretty firmly, they don't actually carry the power of the engine. They just hold the sprocket onto the shaft, so rebuilding the thread could work. Heat may be a problem when buildig up the thread though.

    There may also be aftermarket methods to hold the sprocket on which could be used. For example, Ducati moved away from the lock nut design on my bike, and use a plate to hold the sprocket on. It fits on the spline, rotates one spline to hold the sprocket on, and is then locked in place with two fairly small bolts. You may be able to get a similar idea used on your bike.
     
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  12. Check the thread out properly before you commit to a new countershaft.
    It may be the nut was not done up properly.
    If the thread on the shaft looks OK, buy a new nut, Locktite it on and torque it down properly.
    If the thread is U/S there are other things you can do.
     
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  13. Thanks foot69 and Roderick. This is the second nut failure on that shaft - we caught the first one when doing a sprocket/chain replacement and the nut was hanging on by a thread (pun intended). I haven't tried it with a new nut this time - the one that just failed went on ok and tightened OK... but has failed! So i'm thinking the thread on the shaft must be damaged.
     
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  14. Anto was it locktiite'd the last time? Does the nut have a spring washer under it? I dont know what the setup is, I do know when a spring washer is under a nut it does help to keep tension, in this location with the slack/tight action it gets not sure if it would be of use. If all threads are ok, locktite the bugger and check on it weekly till you feel 'safe' you should know roughly how long and many kms have passed sonce you last loked it, have more frequent checks to keep your mind at peace. Unless you're ready for that upgrade?
     
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  15. It does have a "bendable" washer to grip the nut, not a spring washer . Can upgrade in March! Not soon enough though...
     
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  16. Fix it best you can and wait, almost there mate, hang in there, you deserve the upgrade..
     
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  17. replace the lockwasher with a new one and locktite the nut on. If the thread was gone you wouldnt have been able to tighten it up. make sure the lock washer is fitted correctly as well, its easy enough to do it wrong.
     
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  18. I'll give it a go... a new nut only costs $10 so worth one more try with a new nut, lock washer and locktite.
     
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  19. One easy bodge that has been done before,that is if its a split the case job to swap the shaft and you don't have the money is to do the nut up as tight as you can and do a tack weld on it,minimum heat so you don't melt a seal.Do it in a place that it can be ground off easy when either the sprocket or shaft need replacing.
     
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  20. ideal scenario is to have a hole thru the shaft so a split pin can be put thru after the nut is done up!!
     
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