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COUNTERSHAFT SNAP

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due to improper torque setting (without using torque wrench actually) i have snapped the shaft.

im sure the cost for replacing such shaft will make me  :jawdrop::cry:  

 

however i find a better way to solve this issue by making a new thread inside the shaft a bolt and a couple of washer.

 

just need recommendation how to make sure the bolt wont easily come off.

 

 

Thanks,

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IMG-20140512-WA0001.jpg

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Er.......Locktite?

from 1 to 10 how high is your confident with that sugestion?

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Don't blame yourself.  Torque alone will not break the shaft. There was some other defect.  Your repair has been successful a few times.  As far as keeping the bolt tight - you can't. The better approach is to design a system that the bolt tightens securely against the end of the shaft but not actually clamping on the sprocket.  The sprocket floats just a little.  Works for Honda,  KTM and others.  With that approach the bolt will stay tight. Loctite is still recommended.

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Could the wahers/nut be welded together, and the splined lockwasher be fitted between the sprocket and the largest washer,, bent onto a flat on the washer?

   Looks a good repair so far.

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I would suggest that unless it's an optical illusion, that counter shaft sprocket is worn out.

The same as this.

 

voortandwielzijaanzichtyf1.jpg

Edited by Black_DRZ

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The better approach is to design a system that the bolt tightens securely against the end of the shaft but not actually clamping on the sprocket.  The sprocket floats just a little.  Works for Honda,  KTM and others.  With that approach the bolt will stay tight. Loctite is still recommended.

 

Would that cause damage to the second gear bushing? (I know not what I talk about here)

I thought the clamping force was required to protect a bushing on the other end of that shaft..., and also bikes that run with the CS nut loose become prone to leaking oil from the counter shaft seal don't they? 

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Well I'm glad I'm not the only one and having said that, not glad I am one. Mine came off during a ride on the dirt, jamming the sprocket / chain in the frame / swingarm and hence rear wheel while on the trail at about 50kph. Luckily A Big Skid (puliing the clutch funnily enough has no effect here!!!) and didn't go down. After splitting the chain got towed home.

 

Researching the fix here I went to drill the shaft, for which you'll need a cobalt drill bit, a starting tap and bottom tap.

 

Leaving the engine in, I migwelded a nut to the end of the shaft of the appropriate thread and pitch (can't remember now exactly but it's on here somewhere) to start the drill straight and get an initial bite with the tap. Then once the tap had started cutting, and I had a bit of thread in the shaft, I cut the nut off.

 

To secure the sprocket, I set the float to zero with a washer (with the bolt snugged tight, I can just turn the washer but can't get a feeler gauge in) and used loctite on the threads of the high tensile bolt (which is quite short). I then set the torque at 40 ft/lbs and it has never moved. 

 

I've changed spockets twice with it like this and ridden 3000km both SM and dirt (hard!) and expect I will change the shaft eventually when I split the cases for a BB and ACT gears.

 

Cost was less than $100 for the drill, taps and bolt.

Edited by dark_knight

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DRZdick-

 

Would that cause damage to the second gear bushing?-----Actually no but in this case who cares, it is not the worst of the problems and would get replaced if the transmission were ever to come apart to replace the shaft.

I thought the clamping force was required to protect a bushing on the other end of that shaft------Maybe yes, maybe no but in this case it is not important.  There is more than 1 reason to keep the nut tight (when that option still exists)

and also bikes that run with the CS nut loose become prone to leaking oil from the counter shaft seal don't they?-------No. The oil leak is when the nut comes off and the seal spacer moves out of the seal.

A floating CS sprocket has been proven to work. it is just not the first choice when the original nut clamp system is still functional.

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Could the wahers/nut be welded together, and the splined lockwasher be fitted between the sprocket and the largest washer,, bent onto a flat on the washer?

   Looks a good repair so far.

I think this idea is good. Better to grind the washer to pentagon shape.

Safety wire the bolt to the sprocket.

Any picture so i get the idea? Thanks

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DRZdick-

 

Would that cause damage to the second gear bushing?-----Actually no but in this case who cares, it is not the worst of the problems and would get replaced if the transmission were ever to come apart to replace the shaft.

I thought the clamping force was required to protect a bushing on the other end of that shaft------Maybe yes, maybe no but in this case it is not important.  There is more than 1 reason to keep the nut tight (when that option still exists)

and also bikes that run with the CS nut loose become prone to leaking oil from the counter shaft seal don't they?-------No. The oil leak is when the nut comes off and the seal spacer moves out of the seal.

A floating CS sprocket has been proven to work. it is just not the first choice when the original nut clamp system is still functional.

Aru you referring to the oil seal at the end of the shaft? I beleive there is a retainer plate that prevent it to pop out and leak.

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Aru you referring to the oil seal at the end of the shaft? I beleive there is a retainer plate that prevent it to pop out and leak.

 

No, here's my confusion...

 

I was pretty sure that in all the posts I've read regarding this, the 110 Nm of torque on the CS nut is required to stop the 2nd gear bush from mushrooming. If it does the shaft becomes loose and then the seal can get blown out.

 

But what it might be is that the 110Nm is required to keep the nut tight against the CS (also loctite), if the nut loosens the sprocket starts shifting around then the 2nd gear bushing can become mushroomed and this can make the nut looser leading to the seal being pushed out under oil pressure.

 

I seemed to have formed the view that the tightening force is for the 2nd gear bushing but TBH that never made sense to me.

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No, here's my confusion...

 

I was pretty sure that in all the posts I've read regarding this, the 110 Nm of torque on the CS nut is required to stop the 2nd gear bush from mushrooming. If it does the shaft becomes loose and then the seal can get blown out.

 

But what it might be is that the 110Nm is required to keep the nut tight against the CS (also loctite), if the nut loosens the sprocket starts shifting around then the 2nd gear bushing can become mushroomed and this can make the nut looser leading to the seal being pushed out under oil pressure.

 

I seemed to have formed the view that the tightening force is for the 2nd gear bushing but TBH that never made sense to me.

 

The C/S nut holds the sprocket to the shaft and clamps the oil seal bushing/bearing/2nd gear bushing.  When the nut loosens, the oil seal bushing can pop out and cause a leak (NOT the oil seal, which is held with a separate retainer).  A loose nut also causes wear to sprocket/shaft splines and 2nd gear bushing.

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Pretty sure I'm looking a a Honda CBR600.  Also pretty sure the bolt tightens against the end of the countershaft and the sprocket floats on the splines.  Typical Honda set up.  No problem keeping he bolt tight.  Safety wire is probably for track set tup.

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brian - If you would care to explain your source of confusion, perhaps someone could clarify.

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