Vibration at 85+

[cyberwolf009]

I don't travel the interstate that often, but I have noticed that my ST1300 has a pronounced vibration at 85mph (indicated 90). Not really a wobble, but a vibration that goes away immediately when I reduce speed. The best comparison I can give is that it feels like I'm riding over cobblestones. Today I had some clear freeway and the chance to experiment. The vibration stays when I pull in the clutch, so doesn't seem to be engine or driveline related. It definitely seems more pronounced in the handlebars versus the tank or dash.

I don't see anything unusual with the front tire. I did notice that there is very slight resistance when turning the wheel by hand that gets even slighter for around 30 degrees of travel. Warped rotor, maybe? My back tire has shown some uneven wear, but I would think that would cause more of a full chassis vibration rather than the handle bars. I have done the loosening/tightening sequence for the front axle and forks with Igofar's help, to no avail.

Any ideas? Thanks.

 

[Al st1100]

usually vibrations at that speed IMO would be tire balancing. I would think if the tires are cupped a vibration would be felt most speeds. Since you feel it in the handle bars I would check front tire balancing.

 

[klaproth]

I agree with AL st1100...front tire balance. While you're about it, perhaps a rear tire balance too.

 

[SMSW]

Larry (@Igofar ) would strip and clean the brakes while the wheels are off. Oh, and don't forget Moly Paste on the rear splines if you pull the rear wheel.

On second thought, he would check the torque of the triple clamp bolts...and....

 

[cyberwolf009]

Thanks all. The rear tire is going to be replaced soon and I'll get the front tire balanced while I'm at it.

 

[Al st1100]

Thanks all. The rear tire is going to be replaced soon and I'll get the front tire balanced while I'm at it.

if someone put some fix a flat in there that could be an issue. While it's off break it down and inspect. Definitely spin that front tire before you take it off.

 

[SMSW]

P.S. to my post above, check all wheel bearings when you pull the wheels. Takes about 30 seconds - stick your finger in the axle hole and turn the bearing. It should not make any noise or feel rough. Go in from both sides to check both bearings.

 

[Whooshka]

Any updates? My question is when was the last time the forks were serviced? Even just a fluid change.

 

[cyberwolf009]

No, I haven't gotten a chance to dig into it yet. Hoping for some free time soon to get to some of these good suggestions.

 

[cyberwolf009]

I think the vibration is gone. After getting a new rear tire, the issue seemed even more pronounced, so I finally got around to getting some tools and parts together. First off, the front wheel was out of balance and took an ounce opposite the valve. I wish I would have test ridden after that, but went immediately to fork service. After the balancing and fresh fork oil, the bike rides much better and I felt no vibration on a brief stint close to 100. Now I'm anxious to put some highway miles on to confirm that observation. The only casualty of the service was breaking one of the plastic fork guards - man, are they brittle. Thanks for all the input pointing me in the right direction!