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Light rattle in gearbox when pushing my bike.


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^ it's always worth checking the driveshaft alignment while it's out, but he said earlier that there is no noise while pushing the bike with the transmission in neutral. Since the driveshaft always spins while pushing the bike, a misaligned driveshaft seems unlikely for this problem.

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3 minutes ago, Scud said:

^ it's always worth checking the driveshaft alignment while it's out, but he said earlier that there is no noise while pushing the bike with the transmission in neutral. Since the driveshaft always spins while pushing the bike, a misaligned driveshaft seems unlikely for this problem.

Don't discount the fact that the extra drag turning the in gear gearbox and clutch assy may be enough additional load to produce a noise where none exists when the shaft is running free. Worth a thought.

Phil

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The driveshaft alignment is fine. I marked the shaft halves with white paint years ago to prevent any alignment issues.

While the gearbox was out I held the gear that engages with the clutch assembly with my hand to simulate clutch load on the gearbox while rotating the drive shaft with my other hand with the gearbox in neutral and in different gears. No rattle.

I opened the rear gearbox cover and the gears look and feel fine. All the pegs that secure the nuts are in place.
Except for the gear that's on the drive shaft axle, I found no play.

Picture of peg 1
Picture of peg 2
Picture of peg 3
Video that shows play.

 

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Can you see the "peg" engaged on your input hub?

IMG_20220716_163518-Close-up.jpg

  (Mine appears to have more of the shaft threads showing):

sml_gallery_328_223_734506.jpeg

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I don't have a picture now but the peg is still engaged and looks fine. Not bend or anything.

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Ok, swinging a wild bat here.

Since there's no obvious physical damage or disorder, let's go back to the facts; the only time you have noise is *in gear when the clutch is rotating* correct? If I read the transmission correctly, there are 4 shafts- the output, 2 gear shafts, and the input or clutch shaft. It appears that both of the gear shafts rotate with the output shaft always; that would place the noise on or around the clutch shaft. Check your bearings, see if the cages have any damage or disarray. Does the input feel dead smooth when you rotate it by hand? Is there any detectable movement to the shaft, either radially or axially? Are any gear shifting devices located on the clutch shaft- sliding gears or sleeves, shift forks? (again I'm not familiar with the particular arrangement) Look to see that any engagement dogs are centered between their fore and aft partners, especially if they float on the gearshafts and rotate with the clutch shaft (not output shaft)

That should make a right mess of things.

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The bike has to move so I'm putting everything together again. After that I'll figure out what to do next.
Grazy that I coudn't find anything.  I hope it's not in the drive shaft damper (15 - 18) which I can't see unless I take the shaft out. Which I didn't.
image.png

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1 hour ago, Walterg said:

The bike has to move so I'm putting everything together again. After that I'll figure out what to do next.
Grazy that I coudn't find anything.  I hope it's not in the drive shaft damper (15 - 18) which I can't see unless I take the shaft out. Which I didn't.
image.png

My grandmother had a '82 Oldsmobile 98. After about 90k miles the rear axle started clicking annoyingly. We opened it up and had a look, found nothing. It got worse for a while, and never got better- but never failed either. The boss said, 'Sometimes you just have to let it break to see what was wrong'. My experience has shown that more than a few times over the years. My own 'Sport 5 speed had a 'pop' or 'click' in the driveshaft (I thought) so when rolling in neutral or spinning the wheel on a stand you could hear an audible noise with every driveshaft rotation. I'd had the shaft apart, everything is in fine shape. No aberrations could be felt in either the transmission or rear axle without the shaft. I disassembled the rear axle recently, looking for something. The only change I made was to replace the outside axle bearing in the gear housing. Now, the noise is gone. I can't make any sense of it, can't assign a root cause, but it's dead smooth and silent now. <shrug> If it don't matter, it don't matter. 

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1 hour ago, Pressureangle said:

My grandmother had a '82 Oldsmobile 98. After about 90k miles the rear axle started clicking annoyingly. We opened it up and had a look, found nothing. It got worse for a while, and never got better- but never failed either. The boss said, 'Sometimes you just have to let it break to see what was wrong'. My experience has shown that more than a few times over the years. My own 'Sport 5 speed had a 'pop' or 'click' in the driveshaft (I thought) so when rolling in neutral or spinning the wheel on a stand you could hear an audible noise with every driveshaft rotation. I'd had the shaft apart, everything is in fine shape. No aberrations could be felt in either the transmission or rear axle without the shaft. I disassembled the rear axle recently, looking for something. The only change I made was to replace the outside axle bearing in the gear housing. Now, the noise is gone. I can't make any sense of it, can't assign a root cause, but it's dead smooth and silent now. <shrug> If it don't matter, it don't matter. 

The difference between an Aircraft engineer and a mechanic.

Phil

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Yesterday I finished putting the bike back together again and now the rattle is gone!
After having made two test rides I was not able to reproduce the rattle. Pushing the bike makes no sound at all.
I'm still puzzled as to what it may have been but I had a close look at many parts and everything looked and felt good.
Let's see if it stays this way. At the moment I'm just very happy I can ride again!

When assembling the bike and because the motor was still in the frame I had to mount the clutch in a vertical position. To keep the springs in place while screwing on the clutch disk I wedged some electric wire between the spring coils then pushed the disk against the flywheel while holding the wire taut and then pulled out the wire through the center hole. I was amazed about how well this worked :D
IMG_20220723_140208-small.png

This is the PVC centering tool that I made. Worked perfect the first time!
The PVC end-cap that I bought in the DIY shop had the perfect measurements. I glued some extra pieces on it to align the two clutch discs.
IMG_20220723_142746-small.png   IMG_20220723_141636-small.png

May thanks for all your great comments and suggestions.
I'm all happy now!

By the way:
The clutch plates thickness was at 57% so I reused them.
The oil was coming from two bolts so I tightened them a bit.

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Still some more work to do:
While cleaning up my workbench I found the rubber driveshaft seal ring on my workbench :homer:

Under high load (shifting back one or two gears and giving a lots of throttle) the clutch is slipping which I never had before I took everything apart. I'm sure the clutch assembly is fine. I'll do a search to see what I can find on this.

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40 minutes ago, Walterg said:

Still some more work to do:
While cleaning up my workbench I found the rubber driveshaft seal ring on my workbench :homer:

Under high load (shifting back one or two gears and giving a lots of throttle) the clutch is slipping which I never had before I took everything apart. I'm sure the clutch assembly is fine. I'll do a search to see what I can find on this.

The "O-ring" from where the two halves of the drive shaft slide together?

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