Countershaft leaking and loose nut

[NToxx]

Hi everyone,

I know there is a lot of things written on this issue but any advice is welcome.

I bought the bike with a small leak on the countershaft but the nut was loose so I tought that it was a preload issue. I tightened it to spec (80N.m) but few kilometers after I noticed that it started to loosen.

So I removed the nut, cleaned the shaft, put some loctite as specified and tightened it again. Few hundred of kilometers after it seemed fine, so I put back the plastic cover.

But the issue came back after 1000km... The leak is quite small, but all the back of the bike is dirty (at least, I do not need a chain oiler!). The nut is not fully loose but it does not keep the tightening torque.

I have ordered the shaft repair kit (seal, washer and nut) and I will try again but I am not so sure it will solve the issue.

What do you think about it? I've read that the tightening spec was updated to 100N.m, but it should have been updated in the dealer manual I bought few months ago, no?

If it does not work I may try a drop of red loctite but it sounds like a bad solution for me.

Thanks!

 

[Actionabe]

I don’t really have an input on a solution for you, just the fact I’ve had my front sprocket on and off multiple times and used the lower torque spec and have had zero issues. There has to be something going wrong for your nut to loosen from that tight of a torque..if I remember correctly there is a washer you bend up to lock the nut in place, does yours have that?

 

[NToxx]

Yes the washer is there and correctly bent. I agree with you that there must be something with the nut, maybe it was damaged by being loose with the vibration?
Luckily there was the washer to avoid the disaster of a flying sprocket, but I do not know how many kilometers it was that way.

 

[Actionabe]

My biggest worry would be that someone had the chain too tight because of how confusing the manual is and maybe messed something up that allows the countershaft to wobble and loosen the nut. Would also cause the seal to leak. I would personally see if there is any side to side play in the shaft

 

[svartron]

You may have solved the issue with the repair kit, but keep in mind that also the sprocket needs to sit tight on the shaft. If there is some minimal play it will rattle loose after a while. Some aftermarket sprockets have to much play and an old oem sprocket that was loose before maybe too. In that case a new sprocket and/or Loctite 638 or similar could do the job.

 

[BISavage]

Normally that shouldn't come loose.

Would go for a complete chain kit with proper installation.
There are a number issues that come to mind, not sure whether any of them would loosen the nut though...
... unevenly lengthened chain, poor wheel alignment, incorrect chain tension, crooked or not flat rear sprocket, improper rear sprocket installation, ... list is for sure longer and goes all the way down to something simple like not calibrated torque wrench.

A leak is normally due to a bad seal and not the nut that holds the sprocket, right?

 

[NToxx]

I have mounted the repair kit yesterday.
It is clearly a known issue as the design has been updated : the nut went from aluminum to steel and the seal is different also.

I do not know why they went with this design but there are two seal which can fail : the big radial seal around the countershaft but also an o-ring which is pressed by the preload of the nut via an hollow sleeve. For my issue as the leak was gone when I tightened the sprocket I could have changed only the nut.