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Discussion Starter #1
My bike, 2018 Bobber with 11k miles has developed a rear/driveline harmonic vibration that occurs from 50-60 mph and can be felt in the seat. The vibration comes on and off like a heart beat from 50-60 mph and in 4th gear.

The odd thing is that the problem developed just as I put a new tire on the rear. Tying to rule out a balance issue, I have had the tire balanced 3 times. The last time the tire was broken down and rotated on the wheel. I still don’t like the fact that this tire is taking far more weight to balance than any previous tire. Part of me still wants to believe that the coincidence of the vibration and the timing of getting a new tire points to the fact that I may have a bad tire.

The odd part about the vibration is that it is only in 4th and only in the 50-60 mph range. It is quite noticeable. It is present both on and off of the throttle but seems to disappear when the clutch is engaged. All bolts are tight, swingarm has no play, chain is in spec, and wheel is perfectly aligned. I am wondering if it is possible that a bad tire is being felt at this speed/rpm because the harmonic vibrations coincide with what the engine is doing in this gear/speed. I am tempted to purchase another new tire to rule this out. Worse case scenario there is that I have a another tire for the next time that I need one.

I am afraid that if the wheel/tire is not the issue, I may have a problem in the tranny with 4th gear. That would not be good.

Has anyone heard of any tranny/4th gear problems with this generation of motor? I wish one of you guys was close to me. I would try and talk you out of your rear wheel for 15 minutes so I could rule out where this is coming from.
 

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You say the vibration disappears when you pull the clutch in? That would seem to rule out the wheel or drive.
 

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Do you have a paddock stand? if you have, get a piece of chalk, use the end of the rear fender to rest the chalk against, then rotate the rear tire without letting the chalk move up and down, you should be able to tell, with in a few rotations, if the tire is round and running true.
 

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Do you have a paddock stand? if you have, get a piece of chalk, use the end of the rear fender to rest the chalk against, then rotate the rear tire without letting the chalk move up and down, you should be able to tell, with in a few rotations, if the tire is round and running true.
That is a great idea! Never thought to do that.
 

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Discussion Starter #5
I replaced the tire to rule it out. The previous tire took a lot of weight to balance and the new tire balanced with minimal weight. While it actually feels better, the 4th gear harmonic vibration remains. The dealer also acknowledged the presence of the vibration. The bike will go in for service in a couple weeks to try and find the issue. In the mean time I am riding it to see if it gets worse.
 

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Discussion Starter #6
Bike is in the shop. They can’t seem to determine the cause the vibration yet. We will see.
 

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Discussion Starter #8
Update:

Bike is still at the dealer and I guess they are scratching their heads at this point. They cannot find the source of the vibration. I am told that they are talking with triumph about the issue.
 

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They swapped the chain to rule it out. No difference.
If you feel since 80kmh - 110kmh in 4th gear(and no other speeds) 1-2 second interval vibration from handlebars/foot begs and has quiet wooz wooz wooz sound. This is too tight chain, it must more loose than i tightened(on any other bike i never had tightening issue).
It's easy to rule out, make your chain pretty loose and try out.
 

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when i test rode a bobber the other week the exact same thing happened on the demon bike as the OP described....nearly put me off buying
 

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Discussion Starter #14
Interesting that you had that experience and I hope anyone replies that has had a similar experience because we have reached an interesting stage in this saga.

The dealer has tried to find the issue and have come up with nothing that has worked. I have replaced the tire twice, multiple wheel balancing, swapped chains, all wheel bearings and chassis points checked, engine balance shafts checked, multiple chain tensions tried, etc. They can find nothing wrong with the bike but absolutely recognize that the harmonic vibration is there. The only other option is to pull the motor and split the cases to look for a transmission issue. Triumph recognizes the issue but is not willing to authorize the dealer to do this.

So, where does that leave me....with a dealer and Triumph saying that there is a problem with my bike, but they are not fixing it. I would hope that the documentation and admittance that the vibration is present would help me in the case of a future serious failure. My warranty is over next month. I feel as if I am being pushed away until this is truly “my problem”. Not by the dealer...but by triumph not being willing to authorize them to dig deeper for the issue.
 

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I’m guessing that the only way to escalate this is via a (very good) lawyer to represent you.
It will cost you - probably more that the bike is worth - and you may or may not get a favorable result.
And another outcome is that you’ll have to pay Triumphs costs (or part of) depending on how the law works where you are.
Best case being they refund you for a lemon bike and wipe their hands of this issue.

It really is a shame reading about your problem and I hope it gets solved to your satisfaction!
 

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Maybe slightly off-topic but whilst riding along at 40-50mph the other day I experienced a fair amount of noise, in fact, it sounded dreadful.
Suddenly the noise disappeared. This 'quiet running' coincided with the bike moving from one road surface onto another. Then we were back onto the first surface again and the noise returned.
 

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Interesting that you had that experience and I hope anyone replies that has had a similar experience because we have reached an interesting stage in this saga.

The dealer has tried to find the issue and have come up with nothing that has worked. I have replaced the tire twice, multiple wheel balancing, swapped chains, all wheel bearings and chassis points checked, engine balance shafts checked, multiple chain tensions tried, etc. They can find nothing wrong with the bike but absolutely recognize that the harmonic vibration is there. The only other option is to pull the motor and split the cases to look for a transmission issue. Triumph recognizes the issue but is not willing to authorize the dealer to do this.

So, where does that leave me....with a dealer and Triumph saying that there is a problem with my bike, but they are not fixing it. I would hope that the documentation and admittance that the vibration is present would help me in the case of a future serious failure. My warranty is over next month. I feel as if I am being pushed away until this is truly “my problem”. Not by the dealer...but by triumph not being willing to authorize them to dig deeper for the issue.
I know it's a different bike, but I had the EFI America and had a very similar experience with the buzzing/ harmonic vibration.. it came through the seat, pegs and handlebars.. so seemed to be from the engine to the chassis.. the cause... unbalanced throttle bodies! The triumph tech balanced them up and the vibes were gone!

It seems that this can't be the case for your vibrations, but my point is it was something that didn't seem the be related but was obviously the second piece of the harmonic pairing that caused the vibration with what ever else the bike was doing at 65mph
 

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Discussion Starter #18
I know it's a different bike, but I had the EFI America and had a very similar experience with the buzzing/ harmonic vibration.. it came through the seat, pegs and handlebars.. so seemed to be from the engine to the chassis.. the cause... unbalanced throttle bodies! The triumph tech balanced them up and the vibes were gone!

It seems that this can't be the case for your vibrations, but my point is it was something that didn't seem the be related but was obviously the second piece of the harmonic pairing that caused the vibration with what ever else the bike was doing at 65mph
That’s a good point and something I asked the tech when I first put the bike in for service. I asked (since there is no cable actually going to throttles..drive by wire has these operated by electric motor) if the the throttles could be jumping or surging at this window of speed and gear selection to cause the rhythmic feel. He said that was unlikely.

Judging by your experience, this may be something that I pursue farther. I am willing to look at anything at this point.
 

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File a statement of claim against the the dealer and Triumph before your warranty runs out. A simple statement of claim is not expensive but is a wake up call that you’re not letting it go. It costs Triumph a lot more to address the legal issue than it does to replace the motorcycle. A statement of claim gets their attention rather quickly and action to settle the matter
 
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