Right camchain potential failure

[14TLC]

Have anyone found a solution, or at least discovered what actually causes the right camchain failure on some early production models.

 

I am talking about right camchain rivets being ground at the back side. I have two bikes at the shop with this issue. The rivets are not ground to the point of chain failure but the damage is visible. I am aware that there are cases where the big nut at the clutch basket getting loose and the complete compensating shafts moved back in the engine causing the cam-chain to hit one transmission gear and destroy the rivets. Here it is not the case, the big nut is not loose.

 

There is a play at the compensating shaft, moving back and forth, especially when the clutch has been disengaged, separating the engine from transmission. This play can be even felt when changing gears, especially from 2nd into 1st while keeping the clutch disengaged for about 2 seconds after getting into 1st gear.

 

It is clearly visible that the camchain is getting quite close to one gear from the transmission at the bottom sprocket (at compensating shaft)

 

Is there something to be done in order to save these engines ?

[dirtrider]

29 minutes ago, 14TLC said:

Have anyone found a solution, or at least discovered what actually causes the right camchain failure on some early production models.

 

I am talking about right camchain rivets being ground at the back side. I have two bikes at the shop with this issue. The rivets are not ground to the point of chain failure but the damage is visible. I am aware that there are cases where the big nut at the clutch basket getting loose and the complete compensating shafts moved back in the engine causing the cam-chain to hit one transmission gear and destroy the rivets. Here it is not the case, the big nut is not loose.

 

There is a play at the compensating shaft, moving back and forth, especially when the clutch has been disengaged, separating the engine from transmission. This play can be even felt when changing gears, especially from 2nd into 1st while keeping the clutch disengaged for about 2 seconds after getting into 1st gear.

 

It is clearly visible that the camchain is getting quite close to one gear from the transmission at the bottom sprocket (at compensating shaft)

 

Is there something to be done in order to save these engines ?

Morning  14TLC

 

I am aware of a few failures with the cam chain hitting 4th gear but as far as I know they were all caused by a loose clutch basket nut. 

 

Did you buy that motorcycle new or used?  If used then it's possible the nut came loose on a previous owner & that part was corrected. 

 

If you bought it new with a continuous history then I don't know what to tell you as something is allowing the shaft movement  & chain contact. 

 

There seems to be enough history of these chain contact failures that "possibly" BMW will offer some sort of good-will help so you might start with BMW customer service preferably through your dealer's service department. 

 

If you are doing it on your own then you probably need to dig in & see if you have a failing bearing,  if bearings are OK then possibly shim the shaft so it can't move as far & allow chain contact.  

 

If the motorcycle was bought used then (personally) I would probably thoroughly clean the worn side of the chain as clean as possible (in 3 or 4 places at the highest wear areas) then paint the contact areas with red or white paint. Then ride the motorcycle to see if you have any new contact. If you don't show contact then possibly the contact was repaired, if you are still seeing chain contact then it will eventually fail the cam chain if not addressed.  

 

 

[14TLC]

Back to this topic, the bike is currently in my workshop again. The owner both this bike used and he also check with BMW dealer for repair history. Nothing noted regarding this issue.

 

The dealer suggested changing the cam chain tensioner and the cam chain as solution to the problem and if they find something else they will notify the owner. 

 

Anyway, the owner decided that I should try and find out what could be the issue. The engine is on my table at the moment and these are the findings so far

 

- The compensating shaft movement is 0.20mm measured with dial gauge and I think such play is quite normal

- There are visible marks on the gear in the area where chain rivets make contact

- The gear which is part of the input shaft also have play of about 0.45 mm. This play is present no matter in which gear is the transmission. I expect that here some play should be present in order for the gear to engage with the shift fork guide ring and other gears, but who knows how much this play should be

- One of the needle bearings from the intermediate shaft in the right cylinder head disintegrated upon disassembly

 

I think that the contact is not constant. Maybe just hits the chain during gear change

 

One idea for making more room between the gear and chain is to grind the gear and reduce the thickness

 

Any suggestions are welcomed. I will check for other things also. I would like to find out the root cause for this failure since it is not so uncommon failure and I am sure BMW knows what is the issue but they don't want to make recall about it.

 

[Toter]

Did you determine the root cause of the problem? Seems that intermediate shaft bearing could be the issue.