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High-speed Wobble(?), '15 GSW


Id's_OK

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OK, I've searched for anything relating to tank-slappers and wobbles and haven't found anything helpful. Went on a fairly long trip this past weekend (5-600 mi each way) and the GS would start wobbling above the posted speed limit. I can neither confirm nor deny 20-30+/- over. Anyway…

 

Not quite the Harley Death Wobble, but accelerating in high-speed (I-71 and 75) curves and even a few times going relatively straight, the front end started to oscillate/wobble to the extent I thought it could become a tank-slapper. I let go or at least relaxed grip on the bars, eased off, a little rear brake, whatever, and it never got bad but it's still worrisome.

 

The only things that have changed on the bike are completion of the front fork recall and my installation of Jesse bags. Since I can't imagine how shims and caps on the forks could cause this, could it be the Jesses? Aerodynamics? I think they say not to exceed 85 MPH or something crazy like that. Was a simple 3-day trip, so not overloaded, weight was fairly balanced, etc. Tires were within spec or a little firm (38 front @ ambient temp) so I don't think it's that. No top case (yet) or any additions other than the Jesses.

 

Any thoughts? Could make the trip to SD a little slower than I'd planned.

Edited by Id's_OK
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Christopher, I've had my 2016 GS above triple digits (127 to be exact) with the Jessie bags but had not had the recall on the forks done. Puig windscreen, stock otherwise. Stock Anakee 3 tires. Not a heavy load but my usual bag of clothes for the week, tool kit, pump and first aid supplies. Bike was rock solid.

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OK, I've searched for anything relating to tank-slappers and wobbles and haven't found anything helpful. Went on a fairly long trip this past weekend (5-600 mi each way) and the GS would start wobbling above the posted speed limit. I can neither confirm nor deny 20-30+/- over. Anyway…

 

Not quite the Harley Death Wobble, but accelerating in high-speed (I-71 and 75) curves and even a few times going relatively straight, the front end started to oscillate/wobble to the extent I thought it could become a tank-slapper. I let go or at least relaxed grip on the bars, eased off, a little rear brake, whatever, and it never got bad but it's still worrisome.

 

The only things that have changed on the bike are completion of the front fork recall and my installation of Jesse bags. Since I can't imagine how shims and caps on the forks could cause this, could it be the Jesses? Aerodynamics? I think they say not to exceed 85 MPH or something crazy like that. Was a simple 3-day trip, so not overloaded, weight was fairly balanced, etc. Tires were within spec or a little firm (38 front @ ambient temp) so I don't think it's that. No top case (yet) or any additions other than the Jesses.

 

Any thoughts? Could make the trip to SD a little slower than I'd planned.

 

Morning Christopher

 

Thoughts-- Tires, tires, tires.

 

Start by taking the weight off the front then checking for things like loose wheel bearings or loose suspension parts, if OK then do the same on the rear.

 

If all bearings & suspension parts are tight then look for a tire wear problem (tires can look good but have just enough odd wear to cause a high speed tracking issue).

 

What isn't stock on that bike? Things like large aftermarket hand guards, taller or wider windshield, fender extensions, large skid plates, etc can cause arrow problems & set up a high speed wobble.

 

Then you have the bags, it sure is possible that they are contributing to the wobble.

 

Is your rear suspension height set too high? That can add to a stability issue.

 

It might not be just one distinct thing as it could be a stack up of a couple of issues including wind conditions or vortices off of other vehicles.

 

Grooved pavement & certain tires can also cause a stability issue but that seldom gets worse than just annoying with a feeling of instability & a controllable osculation.

 

 

 

 

 

 

 

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greiffster

Christopher,

You don't still have that wonky handlebar riser/adjuster gizmo on the bike, do you?

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greiffster
No, back to stock. Why, do you know anybody looking to buy some wonky riser thingies? ðŸ˜

 

:) No. Those are weird. I thought you were taking those off and just wanted to rule it out.

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Thanks, Mike (B60) and DR for the detail. Other than the Jesse boxes and seat, the only other material mod is a pair of Clearwater lights. Nothing I can think of to contribute to a wobble.

 

The tires are PR4 Trails, which are worthless offroad but otherwise terrific on wet or dry pavement. The pressure was the first thing I checked so I don't think that's the culprit but I'll inspect more closely for any wear or abnormalities.

 

I'll definitely work through the front end to see if I can find anything 'off' or loose, then check the rear as you suggested. If I can't find anything, I'll get some assistance making sure everything is up to spec. It's definitely ride-able but not exactly confidence inspiring over 90, esp in the wet.

 

Thanks again!

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All good input above. The only thing I might add was there a top box on the bike? If yes, was it heavily loaded?

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Lone_RT_rider
Check the steering stabilizer while you are at it. After all, it's purpose is to reduce wobble...

 

Christopher, AZgman has a point. How many total miles are on that bike? I'm not sure about your generation of R bike, but the steering stabilizers on the R1100R's (Rainy's old bike) were known for being really low quality and failing early. Maybe DR has a better method, but try a quick jerk of the handlebars while on the center-stand with no load on the front end. If there is a bit of movement before you feel resistance from the damper, you might have a possible contributor. As DR has said though, it could be a combination of a few things too.

 

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Paul - no top box, just the Jesse side cases.

 

Shawn - what do you mean when you say 'quick jerk'? Since the damper wouldn't kick in to a straight back or up and down movement, I assume jerk it to one side? That damper is tricky though, as it's already pretty soft/flexible and rotates in every plane/direction...so I'm not sure how to 'check' it.

 

Thanks again, guys!

 

P.S. only about 11k miles on the clock

Edited by Id's_OK
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Lone_RT_rider
Shawn - what do you mean when you say 'quick jerk'? Since the damper wouldn't kick in to a straight back or up and down movement, I assume jerk it to one side?

 

Yes, give it a quick tug on the handlebars. If you get a fair amount of free play before it meets any resistance there is a chance that is a contributor. It should (within a few degrees of angularity) start to build some kind of resistance.

 

Rainy's damper went out under 20K, if I remember correctly. We replaced it with a Hyper-pro unit. I think you remember the bike. :)

 

 

 

 

El%20Paeso%20fall%202005%20004-L.jpg

 

I think you actually rode with us that day....

 

El%20Paeso%20fall%202005%20003-L.jpg

 

El%20Paeso%20fall%202005%20001-L.jpg

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steve.foote

Christopher, the things I would be looking at are the tires and make sure everything on the fork and front axle are tight. I've had the fork tube clamp bolts loosen on my '05 before. Make sure you get the right torques beforehand because many of these are pretty low. If you're running TKC70's, there have been reports of earlier production causing wobbles. Absent that, does the wobble go away when you loosen your grip on the bars?

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Since you mentioned that the bags might be responsible, why don't you remove the bags and test. It's a simple enough test. Let us know.

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Shawn - thought I posted earlier but I guess it didn't take. But yes, I remember that bike and terrific memories of that day!

Thanks Steve. - My mechanic just gave me a full list of torques and other values/volumes so I can check those. No TKCs, I'm running Michelin PR4 Trails. The short answer to the last question is yes, the wobble went away when I let go or loosened my grip. BUT I'm not sure if it was because I let loose or was decelerating at the same time. Was just trying to get home and avoid it getting worse at the time, not testing theories :-)

Ken - how do you check the ball joint? what to look for?

And Avi - great idea (if not obvious :dopeslap:) I'll check that and report back.

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I would go back to the dealer ASAP...let them be the test pilot. Is your 15 still in warranty? Wobbles don't generally get better and a tank slapper can ruin your day quickly. I had an R100RT that really prone to it. The cure was front shock issue (non telelever) Stiction was the issue. Since it sounds like you just had fork work on recall...

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...The short answer to the last question is yes, the wobble went away when I let go or loosened my grip. BUT I'm not sure if it was because I let loose or was decelerating at the same time. Was just trying to get home and avoid it getting worse at the time, not testing theories :-)...And Avi - great idea (if not obvious :dopeslap:) I'll check that and report back.

 

That is an interesting clue and if removing the bags seems to stop the wobble, I would begin to suspect that the rear suspension had too much sag with you, the bags and their contents. The next step would be to put the bags back on add more preload to the rear shock spring to get the rear of the bike ride height back to what it is w/o bags. I had a Kawi 750 GPz that wobbled something fierce under hard acceleration. In this case the chain drive on that bike would make the rear squat quite a bit under acceleration and the solution was to increase the preload on the rear spring to limit the amount of squat.

 

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Wobble causes include worn tires, defective tires, improperly inflated tires (or a combination of these); uneven load or too much weight up high (heavy items in top case); too much frontal area (oversize windscreen or screen positioned too high), uneven road surface; turbulence from other traffic or wind conditions; suspension adjustment or malfunctions; too much speed given any of the items listed. That's a good start.

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