I think I broke my transmission....

Discussion in 'Mechanics Garage' started by OSA 06, Jun 8, 2016.

  1. OSA 06

    OSA 06 New Member

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    Alright folks, here's the scoop.... I noticed today that there was a loud clucking in the transmission chain area today on my way home from work. So I put her up on the center stand to check into things, and this is what I've found out. The horrendous clunking only happens with clutch out and in gear. If the trans is in neutral engine idling, no noise. And the the transfer in neutral and turning rear wheel by hand, nothing there either. So has anyone heard of any internal transmission failures or chipped gears sets that would make this kind of noise??
     
  2. Terry Smith

    Terry Smith Member

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    I'd be checking over the chain and sprockets carefully first. Maybe you have a bolt coming loose or need to replace the chain and sprockets, or adjust then tension? How many miles on them?

    If I put my bike in gear at idle (on the centrestand of course) and let the clutch out, there's plenty of backlash that will cause the chain to snatch and complain. That all disappears with some load on the system (acceleration).

    Having said all that, if the transmission is failing it may be a damaged shift fork or a broken gear dog. Either can lead to a catastrophic lock-up of the gearbox. It's an engine-out/split the cases job to repair, lots of time but not so many parts needed.
     
  3. OSA 06

    OSA 06 New Member

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    I made sure the chain was adjusted properly before I put it up on the centerstand. And I can turn the rear wheel by hand with no noise or binding. Turns very smoothly by hand. I didn't get a chance to pull the chain off and see if it makes the same noise clutch out and in gear. I did notice on the way home that while rolling, I can pull the clutch in and do not hear the clunking while rolling at speed.
     
  4. Tugboat

    Tugboat New Member

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    Transmissions generally just fail. So if the transmission still works either the engine is running rough or your final (chain and wheel bearings) are shot.
     
  5. OSA 06

    OSA 06 New Member

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    Everything in the chain and rear hub/bearing/Brake assembly are in great shape and check out good. And the noise is much louder and more violent then the typical clutch basket rattle, as i dealt with that on my 93 vfr. I'm starting to think Cadbury may be on to something with the possibility of a bent shift fork. So for you few that have dug into these vfr engines more extensively, do any of you know offhand if the 750 uses the same gearsets/shift drum and fork setup as the 800??
     
  6. Y2Kviffer

    Y2Kviffer Insider

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    How many miles on that chain. I know you say it's fine, but one bad spot in it can make a racket when it's in gear, shudder the bike at low speeds, etc...
    Transmission failures a kinda rare in VFR's.
     
  7. OSA 06

    OSA 06 New Member

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    That's kinda what I was thinking on the trans failures, as I haven't heard of any since I bought my first one in 2011. The chain and sprockets are just over a year old, been oiled regularly, and shouldn't have any more than about 2,000 miles on them. I don't really know what the typical life expectancy of a chain/sprocket set are. I do ride it hard and put it away wet.
     
  8. derstuka

    derstuka Lord of the Wankers Staff Member

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    If chain and spockets are ok, it could be the main axle drive bearing. This can happen from repeatedly over tightening the chain. I'd pull the countershaft sprocket off. If the bearings are completely toast, they might even fall out.

    I bought a bike from a guy years ago that I learned repeatedly overtightened the chain. I had the very similar sound and symptoms as you are describing. Turns out, the over-tightening caused undue pressure on the main axle drive bearing and it pretty much wore down until it exploded, then bent the main axle drive shaft and took two gears with it. Ouch.

    Even if you don't overtighten the chain, or think you don't, it is a possibility.
     
  9. OSA 06

    OSA 06 New Member

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    And also, if it was a chain/sprocket issue, a rear hub bearing, or rear brake problem, then I should be hearing the same noise a feel the jolt it causes any time the bike is rolling, no??
     
  10. OSA 06

    OSA 06 New Member

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    Thanks stuka. I did look for the countershaft to jump or move when it was popping, but didn't see anything obvious. I'm going to start tearing it down tonight or Saturday and recheck all the obvious and normal places for rattles and popping in the drive system before I dive any deeper into it, but I'll definitely check if there's any play or signs of bearing failure when I get the chain and drive sprocket off. Thanks for the advice. And keep any other advice/info coming if anyone has come across other causes and remedies for this type of problem!!
     
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