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-   -   HIGH SPEED WOBBLES on my F800 GS (http://www.advrider.com/forums/showthread.php?t=809938)

fractalsource 07-18-2012 11:09 PM

HIGH SPEED WOBBLES on my F800 GS
 
At about 70 mph. or 112.65 kilometers per hour my bike began to feel wobbly on asphalt.
I'm running new TKC 80's.
I assumed it was the non-adjustable, upside-down forks and replacing them, - replacing the springs, and using heavier weight oil was an option for a remedy.
- My local BMW dealer told me it was my tires. - I checked my tire pressure and wear.
I adjusted my bike for my ride, using:
http://www.photos4aidan.com/actions/F800GSPreload.html

On the Interstate without wind or trucks to give me turbulence -
Still, a wobble.

So I bought a steering damper.
Installed it.
Adjusted it, as prescribed.
Wobble gone.
- Stabilized in Idaho.
:rayof
http://i1181.photobucket.com/albums/...e/a2204e2e.jpg

itsatdm 07-18-2012 11:33 PM

There have been many complaints about the wobble. Most have been with tkc80 tires. At about 300 miles the wobble goes away. I initially jacked up the rear preload and dropped the forks 1/4" inch and the wobble went away.

Since that time I have changed out the front springs and cartridge tube. I added a Hyperpro spring to rear and added some preload.

It was a very good pavement bike. I have since added a Scotts stabilizer for off road. It made the bike feel like a heavier bike.

All together, the thing is a rock. I do not care what tire is has on it, it goes where where you point it. The most stable bike I have ever owned.

itsatdm 07-19-2012 04:50 AM

Easy fix. Go ride in the dirt. Never wash it. :evil It must effect more than others, never bothered me.

amackenzie 07-19-2012 05:40 AM

I run the TKC80s and I found airing up the tires helps, especially the front. I've never really had much of a problem with it though.

If you're going to do a lot of high speed highway I'd keep them pretty hard.

Snowy 07-31-2012 07:01 AM

Yep.

Forks...shit. Options...shit. Solutions...like your link says:

Quote:

On ADVrider, there is an extensive thread about the mythic Bitubo fork cartridges, imported from Italy. There’s one guy who actually has them, swears by them, but he does most of his riding in Staten Island. Fuck sake, lads. I need a better endorsement than that before I run out and chuck a bunch a dough at new cartridges.
Things like this stopped me in my tracks. Then there were the failures that started to emerge with the kits.

I have 2 motoX front ends awaiting that perfect moment where I have a surplus of time and money.

Then the BMW front end goes the way of the Dodo.

Front wheel clacking is most likely the disc pads floating in the caliper. Mine makes a hell of a noise. If you pull the front brake on and pump the forks see if it makes the noise then. It'll be the pads for sure.

The wobbles - itsatdm has the way of it. It's a geometry thing most likely. Play with rear pre-load and front height. Raise the rear and drop the front each by 20mm and it changes everything about the way it behaves at freeway speeds.

Some blame tyres, some blame pre-load...I just know this works after figuring it out on my own and then seeing that others agree.

Dream Rider 08-02-2012 08:08 PM

front wobble
 
justbought 2012 f650gs. told dealer front wobbles then settles when i push left/right quick as inavoidance maneuver. usually above 65 mph. However, since the bike settles on its own that is "normal???" bike handles fine other wise. A little more shakey thatn my 1200 GSA behind semi's or in wind,but the bike is about 150 lbs lighter. Is this the same suspension as the 800 GS?

fractalsource 08-03-2012 12:31 AM

F650 and F800 forks/ suspension
 
I'm pretty sure you have adjustable front forks on the 2012 F650 GS.
The F800 GS has upside down, non adjustable front forks. (What were they thinking?)

I like the diagrams for adjusting a bikes suspension, on pages 12 and 13 of this pdf. from Ohlins.
See: http://www.ohlins.com/Products/Owner...M_07241-02.pdf

Having said all that:
I weigh too much for my suspension. (300+)
So, I am getting an upgrade from:
See: http://sasquatchrider.com/products.html

My Scotts steering damper took out my high speed wobbles.
That damper works really well. I like it very much.
It does raise my bars. I can't use some wind screens, like the Windshield - VStream Touring Windshield - by ZTechnik without hitting my mirrors on the sides. Even with the mirror extenders. (I bought one and returned it.)
See: http://www.ascycles.com/detail.aspx?ID=76186

Now, I just have a bottoming out, issue. And a few noises I need to dampen.
Someday, I will dial in, this bike. :jkam

Kevfoley 07-28-2013 01:32 PM

Quote:

Originally Posted by fractalsource (Post 19163435)
At about 70 mph. or 112.65 kilometers per hour my bike began to feel wobbly on asphalt.
I'm running new TKC 80's.
I assumed it was the non-adjustable, upside-down forks and replacing them, - replacing the springs, and using heavier weight oil was an option for a remedy.
- My local BMW dealer told me it was my tires. - I checked my tire pressure and wear.
I adjusted my bike for my ride, using:
http://www.photos4aidan.com/actions/F800GSPreload.html

On the Interstate without wind or trucks to give me turbulence -
Still, a wobble.

So I bought a steering damper.
Installed it.
Adjusted it, as prescribed.
Wobble gone.


I have the same problem on my F800 Trophy when running TKC80s, no problem when off road but a total pain when getting between places. Thanks for the solution.. looks like i need a damper..

Full Power 07-28-2013 05:39 PM

Before you start throwing money at "Solutions", I recommend that you adjust the steering head bearing preload, according to factory specs.
You may actually have a well designed, stable motorcycle, already in possession...... with loose bearings.

chris73 07-28-2013 05:50 PM

Quote:

Originally Posted by Full Power (Post 21974001)
Before you start throwing money at "Solutions", I recommend that you adjust the steering head bearing preload, according to factory specs.
You may actually have a well designed, stable motorcycle, already in possession...... with loose bearings.

Can you post a link for the method of doing this? Mine does this as well

itsatdm 07-28-2013 07:28 PM

Stock suspension and what do you weigh?. My now 5yr F800gs would get the weave on a new TKC80. My bike did not have a loose steering head nut.

The unladen bike has more weight on the rear than the front and my theory is, it does not take much to start the weave on a set of new soft knobbys.

See if this has any impact. Scrunch up as close as you can to the faux tank. If moving your body weight forward improves things, you can either jack up rear preload substantially or raise the forks about 10mm below the line inscribed on the forks.

Even after I re sprung my bike, I still run the forks up a bit. Dirt or pavement it just goes where I point it.

Stabilizers are nice too, I crank mine down on soft terrain or rocks.

Full Power 07-29-2013 01:02 AM

Head Bearing preload is set thus:
Remove handlebar clamp bolts, lift and secure handlebars, for clearance.
Loosen (4) upper fork pinch bolts.
Remove decorative BMW logo from 10mm hex steering stem bolt
Tighten to 25nm
Turn steering 3 times lock to lock.

Loosen 60 degrees
retorque to 11nm.
Tighten fork pinch bolts to 19nm
replace handlebars, tighten front bolts first, rear bolts last

Kevfoley 07-29-2013 01:22 AM

interesting, worth checking the various options, weighing in at 74kg (163 lbs),

It started on Motorways when travelling with loaded bike, increasing the preload on the rear suspension did help, but ultimately it did not fix the issue, same goes for tire pressures, increasing the air in the front tyre would increase stability up to a point but not eliminate the wobble, which when travelling at speed can get a little hairy!

Will check the bearings, and see, but it does not seem loose.
Scrubbed in TKC's or brand new dont seem to make much difference, just a but less bumpy on old ones ;)

Snowy 07-29-2013 05:06 AM

On third set of steering head bearings.

Steering damper.

RMZ front end.

They last longer now with the RMZ front end than before. But I need more kms on it before that is "factual". If I can get double the kms then I'll blame it on the standard front end.

I don't suffer as many rim dings now, I've noticed. I'm much nastier to it than I used to be.

Ceri JC 07-29-2013 05:29 AM

I also have this on TKCs on my F800GS. Fitting a Rallemoto (RM2) steering dampener and setting it accordingly, means that it doesn't become a problem until about 100mph unladen and 90mph fully laden.


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