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CB400 Rear End Vibration

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by jezsmith, Sep 6, 2012.

  1. Hey all,

    I had some rear wheel vibration trouble with my 2010 Honda CB400 on Tuesday night at the South Yarra Boulevard.

    Near the end of a run, I was travelling at about 60 in a straight line (I had just slowed down) and the rear of the bike started vibrating violently for about 30 seconds. It felt like a flat tire, so I slowed down to find a safe place to stop on the left but the vibrations stopped and the bike came right. The guy behind me at the time said he even saw the rear vibrating as he followed.

    I have checked the wheels, suspension, chain and brake (no abs system - so its not that) with some other riders but we didn't notice anything loose, damaged or odd. I kept riding the bike for a few hours, testing the rear brake at different speeds etc and it didn't occur again.

    The chain was only cleaned and relubed on Sunday. The bike has only done 4000km and has never been in an accident (Well... I did scrape the exhaust on a wooden pole once :p). Everything is stock, nothing has been replaced.

    Does anyone have an idea of what could have caused this vibration? Could the chain shift on the sprocket if I had lubed it up too much or if the chain is too loose?

    I'm pretty new to this and annoyed that I can't replicate the vibrations and find the cause. There would be nothing worse than this occurring again but at 80 clicks mid way through a corner.



    Any suggestions would be greatly appreciated.
     
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  2. Get a lady Pillion passenger! I'm sure she'll enjoy it.

    Bad news on the bike though!
     
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  3. was it an uppy downie vibration or a side to side vibration?? do you rekon you could tell?? was it a slower wobble or a fast vibration??
     
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  4. If the chain was skipping teeth you'd have heard it, believe me.

    Funny that it turned up then went away again. Could a bit of crap have got caught on onee of the spokes or the rim of the rear wheel causing a temporary imbalance? Would have had to be something quite substantial though.
     
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  5. It felt like the rear wheel wasn't spinning freely and there was a loudish grinding and rattle noise. I couldn't tell you whether it was an up and down or side to side vibration. I asked the guy behind me but I'm not sure he knew either.

    During that moment, I was certain I had a punctured tire. It was a weird feeling to get off the bike and see that the tire was in perfect condition :p
     
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  6. If I had to guess, I would say it was an up and down vibration as my GPS was bouncing up and down.
     
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  7. Piece of debris caught between something (swing arm, mudguard) and the tire? Then as you slowed it was spat out or fell out? Since it was temporary you'd think it couldn't be wheel bearings or something like that. Perhaps something between the bottom run of chain and the rear sprocket, like a big stick or rock, not able to be run around the sprocket and munched, but able to cause a grinding vibration until it fell out or was spat out?
     
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  8. Sounds like there may have been some sort of obstruction which cleared...

    Check your rear rotor for score marks or damage.
    Give the rear brake calliper a jiggle and make sure it is free to move only slightly.
    Inspect the rear hub while you're at it.
     
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  9. Yes I'd suggest check all rotating parts for scoring. Also, if you can get the rear wheel off the ground (someone can help you pivot the bike up to rest on the front wheel and sidestand), try spinning the rear wheel with the bike in neutral.

    See if it feels 'grindy' at all. Might provide some clues as to whether there is a collapsed bearing, something caught somewhere etc.
     
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  10. Thanks guys. I'll have a fiddle with it tonight and let you know if I find anything.

    I'm hoping it was just debris though that's for sure.
     
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  11. FYI I've checked the sprockets, chain, wheels, brakes and under chassis of the bike, no damage at all, nothing odd.

    Here's to hoping it was debris, cheers.
     
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  12. If you do get the rear wheel off the ground and check for noise, also check for side to side movement. That will help determine if there may be a bearing issue.
     
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