Driveline vibration elimination (hopefully!)

[RollaCosta]

I am not familiar with 'ASC CAL'

What’s wrong with consulting the Rider’s Manual, pp.55-56?

 

[Ceesie76]

Nothing wrong with that (other than that it's on page 51-52, not 55-56).
I never heard of ASC calibration until now, I will execute that next time I take it out, but I would not expect ASC to have any relation to a driveline vibration.

In other news, I had the tire balanced today and that did make a noticeable difference. Testing it again 'dry', i.e. on the center stand, the vibration is much less. Not totally gone, but definitely much improved. Tomorrow I will take the rear wheel off again, to make sure the sheel-hub mating surfaces are absolutely clean. I am beginning to think that the shop I had fit my new tires last year did not do the best job. The other shop I went to today had to add quite a bit of weight to the wheel to balance the tire. Once I am happy with the mounting, will take it for another test run. But the 'dry run' today was certainly very encouraging.

 

[Ceesie76]

So I think I am onto the cause: on the highway today I tested through to 100 mph and the vibration is definitely much less, although still present, but importantly it's now also clear that what is remaining is coming from the rear of the bike, not the middle (= engine) as I thought before. The reason it 'moved' was, I think, before I had the rear tire balanced, the vibration was so pronounced that the whole bike started to vibrate. Now that it's much less, only the rear is affected.

Which means two possible remaining causes IMO:
- the rear wheel bearings need replacing. There is indeed a tiny bit of play there in the wheel
- the actual tire itself has an irregular shape of sorts
- a combination of the two: as the tire is not perfect, any vibration is aggrevated by the small amount of play in the wheel bearings

All this makes sense to me, and also that it only starts at relatively high speeds, not at higher engine RPM.

For my next move, I will replace the wheel bearings and see what that does. If still not to my liking, I will get a new tire. The current one I only put on last year, but it's a Shinko el-cheapo, with which so far I have been satisfied (except that, in the wet, they slide quite easily) but if I need to put on a premium brand, I will happily do so if that eliminates the issue.

For now quite relieved that this is likely the cause, and not something deep within the engine block!

As it was time for a service, I changed the oil+filter, and also put in a new air filter (so, off came a lot of the tupperware on the right side. I had to remove the top side cover anyway to get at the OBD plug to reset the service warning with my Motoscan app). On my next longer run I will do the ASC recalibration.

 

[justscootin]

So today I put in the next size chain rail and put in fresh gear oil. The old oil was quite dark. I also put in a fresh axle seal. The odd thing was, there was one bolt missing from the final drive case cover, and two had a small washer where the other ones did not. As if someone had been in there before me. Even though I bought the bike with only 1,960 miles on the clock, two years old and I never took it for any maintenance to BMW, have done all myself. I've only had some warranty and recall work done by BMW. So ... I put in the new no. 2 rail, assuming that the rail that was in there was the no. 1. But after I got it all buttoned back up, and took another look at the rail I had just taken out, I discovered that that was a number 2 also! Not the original no. 1. So clearly someone had been in there before me, and my best guess now is that it was the first owner who took it to BMW with some sort of complaint, and they swapped in the no 2 rail. So, I opened it all back up, put in the no. 3 that I had also bought (I bought the whole set, nos. 1, 2, 3 and 4) and the second time took me only about 20 minutes.
I then tested to see if upping the chain rail had made any difference. I discovered that, when you rev the engine with the bike on the centerstand, you can actually simulate it going all the way to max speed - the speedo registers the hypothetical speed at the RPMs you rev it at. And, at around 90 MPH, the vibration starts and gets progressively worse until the bike starts to actually move on its center stand due to the vibrations, at 105 or so it's no fun anymore. So, the chain rail nor the new belt or rollers/sliders have made any difference. So, I think Rolla Costa is right, it must be something more fundamental in the engine: balance shaft, vibration damper, a not-exactly-straight shaft, worn bearing - something. But, since it is fine all the way up to around 85, I think I will leave it be for now, just monitor to see it doesn't get worse and I am also looking forward to riding the F800ST that has more power and a higher top-end, hopefully without vibrations! It's also possible, perhaps, that the rear wheel is slightly out of round, or the tire is not balanced properly - I can have those things checked out still.

The washers belong there in the rear casing.

As for the cap screw missing I found on a friend's bike, one was missing and the hole had no thread in it from the factory.

 

[Ceesie76]

Thanks, well the washers were all missing except two random ones. No leaks though. I did replace the missing one in the center with a suitable bolt and there was thread for it in the casing.

 

[RollaCosta]

Now that I’ve worn earplugs when riding, I think I felt that same vibration you are trying to get rid of. Normally it is drowned it the exhaust sounds, but my earmuffs kill the noise so I can feel vibrations more.
My theory is that could come from the fact that the final chain is constrained by plastic rails, not just up there in the air.
I guess we all have to get T-Maxes now, right? Their final belts are sublime, and maintenance-free. You get to re-tension them every rear tyre change.
If Buells had ABS I would have gotten a Buell…

 

[Greg goes wild]

So I think I am onto the cause: on the highway today I tested through to 100 mph and the vibration is definitely much less, although still present, but importantly it's now also clear that what is remaining is coming from the rear of the bike, not the middle (= engine) as I thought before. The reason it 'moved' was, I think, before I had the rear tire balanced, the vibration was so pronounced that the whole bike started to vibrate. Now that it's much less, only the rear is affected.

Which means two possible remaining causes IMO:
- the rear wheel bearings need replacing. There is indeed a tiny bit of play there in the wheel
- the actual tire itself has an irregular shape of sorts
- a combination of the two: as the tire is not perfect, any vibration is aggrevated by the small amount of play in the wheel bearings

All this makes sense to me, and also that it only starts at relatively high speeds, not at higher engine RPM.

For my next move, I will replace the wheel bearings and see what that does. If still not to my liking, I will get a new tire. The current one I only put on last year, but it's a Shinko el-cheapo, with which so far I have been satisfied (except that, in the wet, they slide quite easily) but if I need to put on a premium brand, I will happily do so if that eliminates the issue.

For now quite relieved that this is likely the cause, and not something deep within the engine block!

As it was time for a service, I changed the oil+filter, and also put in a new air filter (so, off came a lot of the tupperware on the right side. I had to remove the top side cover anyway to get at the OBD plug to reset the service warning with my Motoscan app). On my next longer run I will do the ASC recalibration.

Thank you for the info i will get the rear tire replaced probably in about 1 month or
so at the dealer. I will tell the Mechanic about the vibration n the possible cause rear
wheel balancing n the wheel bearings need replacing. But first i will have him test ride
the bike about 90 or so. So he could feel it for himself.

You know i have the Shrinko tires as well. I have not had the slipping of the rear tire on
wet surfaces. Except the medal drain cover for the sewer under the ground. I have
slipped on the corner turn when wet. But other then that they are good.

 

[Ceesie76]

Update is last Sunday I went to replace one of the rear wheel bearings (not the needle one that I had trouble finding, but the other one). After removing the rear final drive oil and cover, ran into the large 46 mm (or 45, different opinions out there) nut holding the rear axle and wheel hub all together. So I put it all back together and ordered a 46 mm 12 point socket that I am now waiting for to arrive. Replacing that bearing apparently involves heating it up / freezing the axle shaft it goes onto, as per the workshop manual. Hope I manage all that. Replacing that bearing is my last action on this issue, I think the tire place would have informed me if there would be any issue with the wheel or tire when they balanced it.
In other news, the F800ST is performing very well and it has absolutely no issue going to 100 mph and beyond if requested, no vibrations.

 

[Greg goes wild]

The F800ST is a motorcycle totally different from the Scooters.

 

[Ceesie76]

Yes I know that Greg. Although, not that different in the end. More protection from the elements, but not all that much more compared to the ST which is a Sport Touring bike with fairings, a small screen etc. But it's also a 2 cylinder motorcycle. What I found is more different is my single-cylinder supermoto Husaberg 550 FE - super nervous racehorse. I don't take that on the highways!

 

[Pmccor]

I had recently gone through all the same iterations as Ceesie76 is now. The 12-point socket is a 46mm to get the axle off. I used the old fashioned way of cutting an "X" on the inner race and break it with a chisel. Driving the inner race back on, I found a 1-1/2 inch pipe is perfect for seating the race and the outer sealed bearing. After all this, I had the tires rebalanced. When all is said and done, I still have some vibration, though diminished. There was an observation that it could be coming from the plastic chain guide. I could see how after going through the rear end and not solving the issue that the guide could be causing the vibration. As I mentioned before, mine seems to be rhythmic and seems to fade in and out and not so much a static vibration at a constant speed. I am not concerned anymore that it is a safety issue so much as a comfort issue. I may dig into it further, but for now I will just contend with it.