Got the death wobble on the Fz6

[The_Paragon]

Yepp, it was dirty my pants kind of moment..

Heres the Scene:
Was accellerating hard from a stop sign. There was a small lump across the road, nothing that would usually cause any issues. As I went over it the front tire lifted a little, again.. nothing that would usually cause any concern. but once the front tire touched back down, she went into a full on death wobble.. I doubt it was close but it almost felt like the front forks were hitting the steering stops from side to side...

I grabbed the bars as tight as I could and rolled on the throttle until it straightened out..
I have no idea if that was the best way to go about it, but it seemed logical at the moment, and I didnt have much time to think about it!

Your Thoughs? Experiences?

Ohh yeah, and this was my second time out on brand new Pilot Road 3's... I cant fully blame the tire, but its not exactly confidence inspiring to have that happen after putting new tires on..

 

[tejkowskit]

Scary stuff. Here's an article on it for you.
Motorcycle Safety Site

 

[outasight20]

I've only had it happen to me once on the FZ6. Same circumstances. Was accelerating hard and the front wheel lifted off the ground slightly. Once it touched back down, death wobble... I don't remember what I did to remedy it, but luckily it didn't end badly.

 

[FinalImpact]

Glad you're OK!
As I've found several things can place the ball in motion as often times its all about circumstances.

I would be curious to know the ride height or SAG front and rear. If you the rider have compressed the rear a substantial amount (such that the nose is up), this could perpetuate the light nose wobble. Is there any work done to this bike from the OEM setup? Read up on setting sag as some of this could be adjusted out to make it more stable all the time. Hint: this suggests it may be on the edge of unstable. Be careful.

Had a very similar thing going up a steep incline as the nose went up and came down. It felt pretty twitchy...

 

[Carlos840]

+1 on the sag and suspension info!

I never had a death wobble, but can definitely feel that the bike is a lot more stable, even under hard acceleration with correct springs and sag.
Make sure your shock is where it should be! FYI 185lbs rider should be on setting 5 to get 30mm of sag. I don't think it's a good idea to go higher than 5 if you are around that weight as you static sag will be close to 0mm and it makes the rear bouncy under hard braking.

Also, although i have never experienced it i was under the impression that the best way to fight a death wobble was to be as light as possible on the bars and roll on the throttle to get weight off the front wheel.
The bike is trying to "fix" itself, and all you are doing by death gripping the bars is fighting it.

Either way, good to hear you're ok!

 

[FinalImpact]

Also, if its not the bikes setup, often times its us doing what we think is right which is wrong. Example is this: if the nose was in there air AND the bike is NOT headed in the right direction, riders apply steering input before touching down. THIS IS BAD! It will cause that issue!
Its basically an invalid input as you wouldn't turn the bars like that if the tire were on the ground. Its because the bike wants to align itself and the input given is out of align so the bike tries to fix it by snapping back into alignment with the direction its headed. << The problem is, this may not be the direction you want to go and fighting it can go very wrong as you cant act fast enough to actually synchronize your input to the bikes so you end up over correcting which can make things worse.

Be careful of the angles when touching down. The bars must be pointed in the direction the bike is going and THEN STEER OUT OF IT!

 

[motojoe122]

I'm not sure how new your tires are, but something like this happened to me.
I had a new set of tires installed getting ready for my first track day. The first ride on the tires it now has a severe had shake which I could feel while riding, worse when I let go of the bars. Long story short, it turned out the front tire was defective, it had a minor bulge just off center of the tread.

 

[major tom]

Is your suspension stock, fork oil, spring, etc? I'd very much like to know. I'm thinking of changing my fork oil to 7.5 wt and adding a preload adjuster. Any thoughts on this anyone? I weigh maybe 185 with gear. Thanks

 

[Gary in NJ]

In addition to what has already been mentioned, head shake can be caused by a cupped tire, worn head bearings or a loose head bolt. Grab a torque wrench and give the front end the once-over.

 

[The_Paragon]

Suspension setup.. gives me a bit of a reminder. I also did a fork oil change. I had a ton of 15wt hanging around for doing some suzuki forks, as well as my mountain bike forks.. so I used that for a fork oil change. The front end is quite a bit stiffer than it was and rebound is super slow. Maybe there inlies an issues. Its quite undersprung for that weight of oil and the slow rebound dampening the heavier oil caused. I had plans on replacing with some lower wt oil. was thinking 7.5 or 10 wt. I also weigh about 185 probably 195 or 200 geared up. Springs are stock.

I'll give the front tire a good inspection and make sure no issues are coming from there.

 

[Carlos840]

Is your suspension stock, fork oil, spring, etc? I'd very much like to know. I'm thinking of changing my fork oil to 7.5 wt and adding a preload adjuster. Any thoughts on this anyone? I weigh maybe 185 with gear. Thanks

I weight the same weight as you, changed to oil to 10w, which was a great improvement, then added some .90kg/mm springs and set the sag, which was even better, now the next step is to add some emulators!

If you haven't done it already set the rear preload to 5, it's already a step in the right direction.

All the info on my setup are here:

http://www.600riders.com/forum/fz6-performance-mods-section/51901-suspension-setup.html

 

[darius]

Suspension setup.. gives me a bit of a reminder. I also did a fork oil change. I had a ton of 15wt hanging around for doing some suzuki forks, as well as my mountain bike forks.. so I used that for a fork oil change. The front end is quite a bit stiffer than it was and rebound is super slow. Maybe there inlies an issues. Its quite undersprung for that weight of oil and the slow rebound dampening the heavier oil caused. I had plans on replacing with some lower wt oil. was thinking 7.5 or 10 wt. I also weigh about 185 probably 195 or 200 geared up. Springs are stock.

I'll give the front tire a good inspection and make sure no issues are coming from there.

My experience with 15W oil was that it slowed the action of the forks so much they did not react fast enough to bumps and dips in the road plus affecting the steering.

Although folks routinely run heavier oils in consideration of how and where they ride, consider that Yamaha designed the forks for 0W oil.

IMO I'd recommend a lighter oil and new springs appropriate for your weight.

 

[The_Paragon]

yeah I figured on lightening the oil up a bit. Maybe go for 7.5 wt. I was told that yamaha "0wt." is actually about the same as most manufacturers 5 wt oil.
Belray's website actually calls for 10wt

 

[darius]

yeah I figured on lightening the oil up a bit. Maybe go for 7.5 wt. I was told that yamaha "0wt." is actually about the same as most manufacturers 5 wt oil.
Belray's website actually calls for 10wt

Yes, the answer is to look at viscosity ratings in CST. There's a really good chart here:
Peter Verdone Designs - Low Speed Damping

 

[bdevries]

Just an idea, but how straight were your bars when that tire came back down? If they were slightly turned I imagine it could cause quite a wobble

 

[major tom]

There you go! IMO the forks are too slow. And I'm nervous going to 7.5.

 

[motojoe122]

Is your suspension stock, fork oil, spring, etc? I'd very much like to know. I'm thinking of changing my fork oil to 7.5 wt and adding a preload adjuster. Any thoughts on this anyone? I weigh maybe 185 with gear. Thanks

I did the pre load adjusters, race tech springs .95, and 15wt oil before the r6s forks. Looking back (of course), .90 springs and 10wt oil would have been better. The preload adjusters worked out well.

View attachment 53145

 

[The_Paragon]

Yes, the answer is to look at viscosity ratings in CST. There's a really good chart here:
Peter Verdone Designs - Low Speed Damping

Good read!! I had no idea there was so much difference between brands of oil! Turns out the Bel Ray 15wt is HUGELY heavier than even most 10 wt oils.
And yamaha 01 oil is actually more comparable to Most 5 wt oils.

Looks like I'll pick up some Belray 7wt or some ProHonda/Showa 7.5 wt,

 

[FinalImpact]

Good read!! I had no idea there was so much difference between brands of oil! Turns out the Bel Ray 15wt is HUGELY heavier than even most 10 wt oils.
And yamaha 01 oil is actually more comparable to Most 5 wt oils.

Looks like I'll pick up some Belray 7wt or some ProHonda/Showa 7.5 wt,

But unless the nose packed down, that's not likely the cause. Did you give any thought to the possibility of the bars being turned upon touchdown?

 

[major tom]

In reply to Moto Joe: I have those adjusters, nice to hear they worked well. Did I miss how much you weigh? And your riding style preference is what?