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This weekend I replaced the chain and sprockets on my '09 Bonneville SE. Baltobonneville's Sticky on chain replacement was mighty useful (thanks, Balto!).

I have 24K miles on this chain and I knew it was near needing replacing as both the front and rear sprockets were showing some wear (you can see it a bit in the photo below), and, curiously, I was hearing this strange 'click, click, click...' noise as I pulled her into the drive way a few days ago. So up on the jack she went, off came the sprocket cover . . .

[/IMG]

. . . .and I grabbed that big nut with my fingers and was able to jiggle it back and forth about 1-2mm each way. When I bent back the locking tab on that washer, the nut just freely came off by hand.

Now, that thing is supposed to be torqued at 132 nm or something, and I couldn't believe it was loose, the only thing holding it on was that locking tab...so I guess that did its job.

That nut has never been taken off, as this was the original chain, so I am wondering if sometimes those buggers just work their way loose. Anyone?
 

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Well, at least it wasn't hard to remove. Half the job is done. :D

I've noticed an occasional bit coming loose when I knew that it was properly tightened (by me). The oil filter and one of the main nuts or bolts for the center stand come to mind.
 

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Discussion Starter #3
Actually, now that I think about it, it was mighty convenient. :)

You see, I had cut the chain off before removing the sprocket, and if that nut were tightened down correctly, it would have been tricky to remove it with only the bike in gear to keep that nut from turning. With the chain on, and the brake pedal pressed, it was a snap to torque the new nut back up to spec.
 

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I had the same thing happen on my Daytona 650 recently....the nut must've stripped itself at some point and just came right off by hand very easily.....I think only the 'path of least resistance' kept the sprocket on the shaft, which may well have been the reason the nut got stripped in the first place??
 

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Lots of instances of loose sprocket nuts just on this forum right through the Triumph model range. A search reveals lots...:eek:
 

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No kidding Forchetto? I was so surprised when I found mine loose that I thought it must be rare because I can't figure out how that nut can loosen like that with the tab on the lock washer bent down. How is it possible?

Anyway, the only searching I did was on sprocket 'replacement' so I missed the bits on the loose nuts. It's not good to have loose nuts! :)
 

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No kidding Forchetto? I was so surprised when I found mine loose that I thought it must be rare because I can't figure out how that nut can loosen like that with the tab on the lock washer bent down. How is it possible?

:)
How did the washer look Juni??....I would've thought the same thing as you, in fact I bent mine down onto two sides of the nut just to be doubly sure...however, it seemed as though the shaft friction had worn the washer wafer thin to nonexistent, at which point the whole spline-fitting thing became useless and allowed the nut to work loose...it's something I still need to remedy properly, I'll have a go at it tomorrow hopefully and post up my findings.
 

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Discussion Starter #8
How did the washer look Juni??....I would've thought the same thing as you, in fact I bent mine down onto two sides of the nut just to be doubly sure...however, it seemed as though the shaft friction had worn the washer wafer thin to nonexistent, at which point the whole spline-fitting thing became useless and allowed the nut to work loose...it's something I still need to remedy properly, I'll have a go at it tomorrow hopefully and post up my findings.
It really looked fine. Here is a photo. You can see that the tab is fully bent over. I was able to move the nut back and forth a but, but because of the tab it would not turn all the way around.



I like the idea of bending down a second tab. And I'll surely be paying more attention to it going forward.

And I'm going to be interested in seeing how you fix things on your bike. Crazy stuff!
 

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Discussion Starter #9
Okay, I've looked at a few other threads where loose countershaft nuts have been found. All reported a 'clicking' noise. That's exactly what I heard too.

So when I think how it's possible that the nut can come loose is if the sprocket, washer, and nut all move together in the shaft, slowly, over time, to loosen up. But then I see the splines on the shaft like this:



and it blows that theory out of the water. The sprocket can't turn on the shaft because of the splines.

So you know, I'm not really being obsessive here, I've not done a lot of wrenching on motorbikes until I got my Bonnie so I'm learning as I go, I'm just trying to figure this one out. It's strange to me is all...
 

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when I changed to an 18T front sprocket mine was loose too...I don't recall the clicking sound but it was a couple of years ago. Maybe I should go check it tomorrow .... hmmm
 

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So what does the Tab do?

So the tab is bent to the nut. So what stops the tab turning with the nut? Usually the tab is bent the oposite direction as well to lock the nut to something that cant rotate, like in wheel bearings. Sprocket needs holes that you can distress the tab into as well. Reckon a big spring washer would be more reliable.
 

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So the tab is bent to the nut. So what stops the tab turning with the nut?
The washer also has matching splines, just like the sprocket, so it's held to the shaft the same as the sprocket. Being just a cheap steel pressing it's not a very accurate spline, unlike the machined ones in the shaft/sprocket, so it can move by a very small amount, maybe enough to loosen the nut.

See the tab washer here:



We can't really use a spring washer as the nut is undercut to fit over the end of the shaft.

A bit like the one on the left of the picture:

 

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Loose sprocket nuts have been mentioned right back to 2001, when I changed to an 18t front sprocket back in 2003 the nut was just as loose as the OPs. Clean the threads, use a new lockwasher and torque the nut up correctly, bend the lock washer over and punch it in nice and tight, you won't have any more problems. Personally I think the looseness is down to lack of attention when the bikes are assembled ie the factory(or dealer). Haven't had aa correctly tightened nut come loose on either of my bikes.
 

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More irrelevant and unhelpful nonsense from me, but I much prefer the Honda method of letting the sprocket "float" on the splines, which gives a measure of self-alignment. The sprocket is provided with a couple of threaded holes into which a plate is fixed to keep the sprocket from coming off. The plate has splines, but they're offset to the shaft splines so once fixed onto the sprocket it can't come off.

The great advantage is that there's no drama when removing or replacing sprockets. No huge 36mm sockets to buy or torque wrenches or breaker bars are needed, no holding tight onto the brake pedal to stop the engine rotating, no messing bending and straightening silly washers, just use an ordinary 10mm ring or socket wrench found on anyone's toolbox:





Here's what the final assembly looks like with the two M6 bolts removed:

 

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It seems to me that if the gear shaft (2) is slotted, and the sprocket gear (23) is slotted, and the locking tab (22) is slotted (newer P/N are) and bent in against the nut the only way that the nut (21) could become "loosened" is if it was never tightened down flush with the base (20). I just don't see how that nut would turn with that locking tab bent in on it. :confused:
 

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Maybe a little locktite would be a good idea...
I use Locktite on both sprockets on my Tiger 955i and Daytona 955i, both of which were previously loose -- a typical problem as others have pointed out. I still check them from time to time, although no problem observed since.

 

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I am on board with the never torqued properly from the factory. I've found that Triumph (and I'm sure other mfg's.) are terrible at proper torque settings. I never found loose bolts, but I have had many that were several times beyond torque spec. Enough that when removing the bolt for the first time it would strip the threads.
I did my first sprocket change at 2,500 miles and have done 2 or 3 more since then. I now have 40K on the bike and that nut always takes a 3ft. breaker bar to brake loose. If it is properly torqued and the splined washer is fully bent over, it would be difficult for the nut to loosen. It is possible though that over time the washer will flatten out from the torque of the nut & engine vibrations. This could cause the nut to loosen slightly.
The moral of the story is do regular checks on your bike for loose bolts. In years gone by it was recommended by all bike builders to check all bolts during regular maintenance. Motorcycles vibrate & take a little more of a pounding than your Mini-van.
 

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Maybe a little locktite would be a good idea...
Is this a good idea? I mean, Ive changed the chain 3 times now. All three times, that nut was loose. I hear that clicking sounds...but chock it up to a dry/dirty chain. The sounds normally goes away from a good cleaning and spray down
 
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