Driveline vibration elimination (hopefully!)

[Ceesie76]

In a few other threads I reported that my 2016 C650 Sport with 13,500 miles on the clock last week developed a driveline vibration at higher speeds, upward of 75 MPH (120 KMH) that gets progressively worse the faster I go. It did not use to have this, or at least not nearly as noticeable. I concluded it would be better to create a new thread to document my attempts at finding and eliminating the root cause, for future use.

So far, I have come up with 4 likely causes:

1. Dirt in the CVT part
2. Malfunctioning torsion vibration damper. As the name suggests, I imagine it does an important job in managing engine/driveline vibrations, so I bought a used one off Ebay: https://www.ebay.com/itm/254857202406 Original ones are available from BMW but at close to $700. I imagine they don't break easily, but my fear is that one of the internal parts (a heavy-duty spring, I imagine, as with car manual clutches, of which there seem to be 3 inside) has broken in two. Doesn't happen often, but in my years I have had broken valve springs and car suspension springs, so it can happen. Unfortunately, this thing turns out to be deeply inside the cranckase, driven by the crankshaft through a heavy-duty chain, so replacing it would be a major-major undertaking necessitating (I think) splitting the crankcase. What's more, I have not been able to find any reference to it in the service manual, and it may not even be installed in my engine as even that information seems conflicting depending on the source you look at. So, fingers crossed it's not that!
3. too much play in my final drive chain. I ordered the 3 oversize chain guides/rails that we're supposed to install in 15,000 mile intervals give or take, depending on the degree of stretch of the chain. I measured (thanks again Delray!) the play by removing the oval black 'BMW' plastic plate and best I could tell the play is just about the maximum allowed (perhaps a bit more, or a bit less - hard to get a precise measurement) so I am going with this possible cause as the most likely one. Parts (second stage rail, fresh oil, gasket etc etc on the way). I did notice the inside of the case looks quite dirty. I have owned this bike since early 2018 when it had less than 2K miles (I paid $6,500 and still think that was a real bargain!) and have ridden it almost exclusively in Los Angeles as my commuter for the 7 mile trip each way each day. So, tons of brisk accelerating/stopping, lane splitting, short rides. I also like to go faaast so I think this bike has had a hard life so far which may well mean that the chain is indeed stretched to the point where it can cause this vibration at higher speeds. We'll soon find out.
4. Drivebelt is worn out. Given the information in item 3, and the fact that BMW likes to see us replace the belt at 12,000 miles, which I have exceeded, I can't rule out the possibility that the belt is worn. In fact, recently, I was noticing that after coming to a stop, I smelt what seemed to be 'burnt rubber' .... First I thought I was imaginging it, then I thought it was from another source (road works e.g.) but since it happened a couple of different times, I started to think it had to be the bike. Not sure what it could be, other than the drivebelt? Nothing else made of rubber or similar that could smell the same, as far as I am aware. Pretty sure it wasn't the brake pads or the tires. I haven't noticed the smell recently, but that may not mean anything, beyond that it is possible the belt is worn/frayed/whatever and I need to change it. Since I recently moved from Los Angeles to closer to San Diego, my commute increased from 7 miles each way to ... 120 miles each way. Fortunately only once a week and I don't mind, but because I now pile on more miles, I decided to order 2 belts from CarpiMoto (the Mitsuboshi brand) just now. Total cost came to $180 including fast shipping. I also ordered the Easyboost CVT tool set from France, that came to another $128 delivered - I was going to need that set anyhow sooner rather than later. Still need to order the grease etc for the CVT clean/re-install. I will also order new CVT rollers and sliders as well, as that's due now according to the service manual.

Will report back on all of this as I perform the work. I may not find out which of the possible causes is responsible for the vibration, since most of the work will be done at the same time rather than incrementally with trial rides in between.

 

[Delray]

Interesting report, thanks. Look forward to updates and good luck getting rid of that vibration.

FWIW, I've used this grease in CVT and wheel work on my GT's, Burgmans and Silver Wings. Much cheaper than BMW's version and more easily available.

$6500 for a two-year old Sport with 2k miles is an absolute steal -- and apparently you ride it like ya stole it ;o).

 

[Ceesie76]

Thanks Mike. Actually that Unirex N3 is exactly what the workshop manaul calls for, I've managed to track some down in the form of a tube issued by Honda (same grease) as I was unable to find it stateside anywhere earlier today.

 

[RollaCosta]

1 and 4 are unlikely to cause vibration, worn drive belt may cause "floating torque" e.g. when you want to overtake on highway you feel a drop in torque and only have to rev even higher, not much happening because the belt is so worn it is smaller in width and softer and heats even more, making it even smaller and even softer... until it tears apart.
"Dirt' gets pushed away, don't worry. Unless you pulled it from a swamp where it's got goo in the CVT, it is not dirt.
So yes, put new chain rails and see. Hopefully you won't need more but I do not like your chances, my bet is on (2).
Because I have had not changed rails for up to almost 50K km and did not have such "driveline vibration" as you described.
There may be a reason behind the "steal" pricing...

 

[RollaCosta]

Another possible reason is clutch, which I think is the worst part of BMW's design, especially coming from the ultimate, sublime multi-plate wet clutch of the T-Max 530.
Mine has been well due for spring replacement at 26000 kms. Had those vibes when starting, then 120-130kmh speed range.
Malossi sells a set of clutch springs, I put the white ones in.

 

[Ceesie76]

Thanks Rolla - we'll see once all the parts have come in to do the various tasks. I do hope it's not the torsion vibration damper, that would be a major undertaking to replace. As for the 'steal pricing', I have the used part but haven't installed it yet. Given how rare any reference to this part is on the forums and inside the BMW workshop manual, it's probably extremely rare for it to break. But, if all else fails, I will replace it.

New Mitsuboshi belts arrived all the way from Italy today (in 4 days!) - a lot faster than the chain rail I ordered on the same day from a BMW dealer in ... California - as of this morning, that had not shipped yet.

 

[Ceesie76]

Small update is that, while I am still waiting for some of the necessary parts to come into to do the chain guide swap and belt change, I did do my commute yesterday and today and, interestingly, the vibration has become much less in the 75-90 MPH range. So it does not seem something 'broke and that's it' but more wear/temperature/conditions related which to me points away from the torsion vibration damper (although who knows until I get to the bottom of it). At least I was able to ride without any vibration at all upwards of 85 MPH.

Other update is that, becoming aware of being reliant on just the one motorcycle without any backup, I yesterday bought a 2007 F800ST with 11K miles on it, for $2K, in really nice shape. Did a long test ride to make sure I would like it. Picking it up this weekend.

 

[RollaCosta]

Does the torque (power) float at all?

 

[Ceesie76]

Not noticeably no.

I decided to do a test yesterday and pulled it to about 100 mph. Vibration returned and, interestingly, remained also at lower speeds, around 70-75 mph for a while, then got less and less until it was 'back to normal'.

 

[Ceesie76]

Today's update is that I replaced the CVT belt, rollers and sliders as per the shop manual. Bottom line is there's no change in the vibration that still occurs, as before, beyond 85 MPH. No noticeable change in the acceleration either, but the engine does run at few hundred RPMs lower across the range and when accelerating briskly.
The old, original belt (labeled 'Mitsuboshi') looked fine, as did the rollers and sliders. I measured the belts with a caliper and the new one is .9 mm wider than the old one (23.2 vs 24.1 mm on the inside), so that's the amount of wear after almost 14K miles. The rollers were barely different: 29.8 mm diameter for the new, against 29.7 mm for the old rollers. The new sliders fit much more snugly than the old ones, and I had to tap them in with a rubber mallet.
Hopefully the 'stage 2' chain rail will come in soon, so I can see if that makes any difference.
The new belt, rollers, sliders, chain guide, transmission oil, along with engine oil & filter, air filter and some other things, the whole 12K major service will have cost me about $450 in parts. As we know, at BMW the new CVT belt alone will be more than that.

 

[RollaCosta]

Besides a possible issue with the clutch, there may be something about the output shaft and its bearing.

 

[Ceesie76]

Thanks, that makes sense.
The clutch looked to be in very good shape, there does not appear to be any slippage at any rpm, it appears to function properly. But it would be very easy to swap it out for another unit to test this possibility if it comes to that.

 

[Greg goes wild]

I have a C 650 GT 2016 as well bought it a few yrs ago n i have that same vibration for the
past 2.5 yrs When i hit 75 mph n higher. But it seems to go away at higher speeds like 100
mph. Glad i am not the only one who has that vibration.

 

[Ceesie76]

Thanks Greg. It occurred to me that I've only recently started riding at highway speeds and that it's possible this vibration has been there for much longer during my ownership (since 2018) but I've never gone fast enough to notice it until now.

Yesterday the new chain rail (no 2 of 4) arrived so in the next few days will install that, and we'll know what influence if any that will have.

Meanwhile yesterday I went through my new-to-me 2007 F800ST with a fine tooth comb including checking the codes stored/present with my motoscan app, the only thing amiss seems to be an inactive TPMS sensor. It rides very nice and with 85 hp on tap, quite peppy as well. Very pleased with it so far.

 

[Greg goes wild]

I do not think it's a major problem with at the higher speeds the vibration does get worse
like about 90 MPH n then i have hit 110 on this bike n i did not notice the vibration.
Maybe cuz i was racing a REAL motorcycle n blew him away first time i ever did that.
That's the only time i will go that FAST on my BEEMER even though it was a smooth ride n handled very well at that speed. 110. Another group member on here stated he did 107
so i had to see this bike go that FAST. Good to hear you like the other bike as well. But you
probably will do away with the BEEMER since you got a FASTER bike.

 

[Ceesie76]

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.

 

[Greg goes wild]

Thanks for the info i had a feeling it was going to be something else instead. Now do about
107 mph on the hwy n see IF that vibration gets worse or not.

 

[RollaCosta]

Next try re-balance the rear tyre, and also I assume you have run ASC CAL. in SETUP?

 

[Ceesie76]

Yes will try balancing the rear wheel - I noticed yesterday that there is no balancing weight on the rim anymore so it may help. But it doesn't feel like it's coming from the tire, it really feels like it's coming from the driveline someplace
I am not familiar with 'ASC CAL' (I assume that means Calibration'?), is this in the setup menu, or in Motoscan? Thanks for all your suggestions.
@Greg I am not trying to go beyond 105 mph as the vibration at that point feels bad enough not to want to push it any further.
Rode it again yesterday 240 miles and up to 85 it's fine, so it's usable enough. Switching next week to the F800ST for my commute, looking forward to that.

 

[Greg goes wild]

Yes will try balancing the rear wheel - I noticed yesterday that there is no balancing weight on the rim anymore so it may help. But it doesn't feel like it's coming from the tire, it really feels like it's coming from the driveline someplace
I am not familiar with 'ASC CAL' (I assume that means Calibration'?), is this in the setup menu, or in Motoscan? Thanks for all your suggestions.
@Greg I am not trying to go beyond 105 mph as the vibration at that point feels bad enough not to want to push it any further.
Rode it again yesterday 240 miles and up to 85 it's fine, so it's usable enough. Switching next week to the F800ST for my commute, looking forward to that.

I only have hit 100 n higher 2 times n that's is all That 110 was with another motorcycle
trying to beat me n he lost. That was on hwy 59. I usually keep the speed at 65 no faster.