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Old 06-21-2011, 02:52 PM   #1
Tatnall007 OP
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Eh? F800GS vibration at a specific speed

My 800GS has a vibration through the handlebars that is quite noticeable at 40mph. It gets better either slower or faster, but it always there.

Dealer:
Its the balancing. I static balanced it and then took it back to the dealer for a spin balance. It was the same.
Its the tire. So, we replaced the tire with another (Tourance). It was the same. I then replaced the Tourance with a like pattern Shinko. It was pretty much the same. I replaced the tube also when I swapped to the Shinko -- the Tourance is back on it now (Tourance on rear).
Its the truing. They trued it. It was the same. Not sure if they checked the roundness, but there is no visible hop.
They say that any big dual-sport with a 21" front wheel is going to have some vibration. I buy that explanation a bit, but other GSes I've ridden don't have it and my KLR650 didn't have it.

Me:
Initially I thought it was a tire or wheel issue, but it has proved very elusive...
Tried different tire pressures.
Checked and retorqued the steering head.
Checked the brake rotors and axle to make sure they were straight - they are.
Replaced the front bearings since one was a little notchy at 10k miles.
I've put about 700mi on it now done the following in that time:
Rear tire checked for true and balanced.
Replaced the chain and sprockets going with a slightly lower gearing.
Added a Scotts under-bar steering damper. [Love it!]
Changed to Hyperpro springs front and rear with heavier fork oil.
...it is still the still the same!

It is more of an annoyance on road than anything else. Off road, its a non issue. I can pretty much ignore it now, but it just irks me and anyone else that rides the bike notices it pretty quickly.

They don't all do that, but does anyone else's?

Any suggestions for next steps?

I'm thinking:
Find someone that will loan me a front wheel for a test (Seattle area). I'd hate to go down the below Woody paths and have it be a chassis or rear wheel issue.
Take it to another dealer and try my luck.
Send it to Woody for checkup.
Buy a front wheel from Woody. I don't ride off road aggressively, but when I put the TKCs on it and hit fire-roads and two track, I'd prefer to have something stronger (based on other's reports of bending wheels).
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Old 06-21-2011, 04:01 PM   #2
mapuda
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All of your investigation and remedies presume a chassis vibration. Have you put the bike in neutral and revved it the same RPM that you are at when you feel the vibration and see if it is present?

For a cheap solution I bought two pairs of gel grips, cut the ends of the two right hand grips and slid them over my BMW grips. Then I put the left hand grips on my mountain bike. I no longer feel as much vibration through the grips as I did before.
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Old 06-21-2011, 04:57 PM   #3
Tatnall007 OP
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Thumb

It is less of a vibration that will numb hands and more of a shimmy (technical terms). At 40mph, the bars shimmy back and forth a bit.

I can definitely deal with vibration from the motor (even one that resonates through the chassis) or the tires due to the tread blocking, but this is different.

I am running a 16x41 sprocket setup now which is pretty good for pavement. I have a 17 and a 15 front that I will try for pavement and dirt respectively.
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Old 06-22-2011, 04:56 AM   #4
JRWooden
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I think there were some guys talking about the same issue over on the UKGSERs forum but I can't locate the thread just now ... it is an older thread, or my mind is playing tricks on me ...

http://www.ukgser.com

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Old 06-22-2011, 01:09 PM   #5
mapuda
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Tatnall007 have you tried increasing the air pressure in the front tire? I get a shimmy if my Shinko 700 is less than 38 PSI and I am accelerating above 80mph. (don't ask Vegas traffic)
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Old 06-22-2011, 04:08 PM   #6
itsatdm
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Quote:
Originally Posted by JRWooden View Post
I think there were some guys talking about the same issue over on the UKGSERs forum but I can't locate the thread just now ... it is an older thread, or my mind is playing tricks on me ...

http://www.ukgser.com
I do remember that. I recall he was from Australia and eventually got his engine repaired or replaced. Not much help without the thread, but it was an ordeal for him to get around the "they all do that" syndrome.

He posted here also.
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Old 06-22-2011, 07:43 PM   #7
bpken11
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Same issue

I have the same problem. My shimmy started right after the dealer put on new rotors. Took it back and got the same lame answers you got. Balance, nope, need a new front tire, nope, need to retorque,nope, nope, nope! Nothing works! Mine starts at about 50 and is gone by 60 mph. What makes me crazy is that until those rotors were changed there was no problem. I am just living with it for now, but it would be great if some one had the real answer to make this go away!
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Old 06-22-2011, 08:13 PM   #8
itsatdm
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Who ever the missing Aussie was, I think he finally found a dealer who lent a bike, then the op and mechanic traded back and forth on the bikes.
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Old 06-26-2011, 10:03 PM   #9
Tatnall007 OP
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I have tried various air pressures. It does change the feel, but the vibe/hop/shimmy is still there.

If I hadn't checked several times I would swear that the front tire is out of balance, not fully beaded, or out of round.

The dealer says that the long travel suspension along with the 21" front tire can cause this sensation. Some are better, some are worse, but ... wait for it ...
"They all do that" I'm still not buying it.

I'll keep trying to find a front wheel to swap in or a dealer that will try mine back to back with another and have an epiphany.
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Old 06-27-2011, 03:37 AM   #10
capt_enduro
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I get the same shimmy - especially if I'm running zero on the pre-load. It can be quite bad if the bike is heavily loaded towards the back with gear.

Just for fun, crank up the pre-load in 5 turn increments and test. My shimmy goes away as the pre-load is cranked up. I've found that when I've measured sag, the wobble goes away at just about the point where the sag would be about right.




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Old 07-23-2011, 04:14 AM   #11
bpken11
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Was in for service yesterday. Tech says that is normal! It's making me crazy!
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Old 12-08-2011, 08:47 AM   #12
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Get this one up as i get the same vibration (not good) on my brand new F800GS Trophy. The vibration starts at 60km/h and ends after 80km/h.
I mentionned it to the dealer for the 1000km inspection and he said he only did a balance of the front wheel, but .....Problem is still there.
After reading the whole thread here i think i will play on my preload (that is at minimum for now) and see if it change anything.
If nothing change, i will go back to dealer and ask him to fix that, no alternative will be given, the bike is new and this should be considered as a safety issue. Will stay tune!
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Old 12-08-2011, 07:35 PM   #13
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F800GS vibration at specific speed

Just purchased a 2012 F800GS Trophy Edition with Pirelli Scorpion Trail tires. I have only put 400 miles on it and I too have noticed a wobble or shimmy at 40 to 50 mph. It is very suttle but obviously there. Normally this would be a tire/wheel balancing issue and solved by spin balancing the tire, wheel with rotors as a unit. A static wheel balancer does not deal with the dynamic forces as the wheel assembly spins so it will not balance the wheel as accurately. You are still only as good as the person that operates the spin balancer. The wobble/shimmy after replacing the brake rotors that occured to one owner was caused by the wheel assembly not being rebalanced. I am going to re true the wheels then mount up some Heidenau K60 Sport tires and spin balance them. I will let you know if the wobble/shimmy condition exist with new tires or it corrects it. As far as the preload adjustment effect on this problem you are adjusting the amount of rake and trail by raising or lowering the rear of a motorcycle. So the front end is responding by moving the steering wobble up or down in mph. Just my two cents on this as a mechanic.
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Old 12-09-2011, 10:16 AM   #14
señormoto
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Standard troubleshooting process for vibes:

Tighten ALL visible bolts to spec
Check your rear shock mount points
Check your front fork and bar mount points
Check your axles for good measure
Try different tires - some will vibrate at different speeds where others have no vibration at all
Take luggage off if you have it

Process of elimination really. My F800 was doing the EXACT SAME THING a month or so ago, turns out my luggage rack mount points were loose. But it did it at the same speed - 40mph in 3rd and only with luggage.
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Old 12-09-2011, 10:59 AM   #15
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mine did it with the stock tires. It does not do it with the TKCs. So I wrote it off to the tires
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