Terrible Headshake and the solution

[RAVENRIDER]

Just keep your hands on the bars and it's a non-issue.

+1.

I upped the air pressure in the front 021 on my 08 FJR as suggested and it didn't make a difference. The headshake is crazy compared to the several bikes I've owned in the past - some of which wore 020s and 021s.

It's just the nature of this beast, and nothing that can change my opinion that the bike is still amazing.

I just ordered a barn door for the bike - the Cee Bailey +6 +6. It will be interesting to see what effect - if any - that shield will have on the headshake.

 

[Rondo777]

I've had mild headshake issues with my previous tires, Azaros, Storms. A couple weeks ago I put on a set of Roadsmarts and the shake is gone. Mounted myself with my buddys HF setup, Marc Parnes type balancer.
Side note: I am liking the Roadsmarts even more after putting several hundred miles on them. The bike feels a little sportier, maybe holds a turn easier with less pressure on the bars to keep it there. Traction is A+

+1 on the Roadsmarts. I have a little over 1000 miles on mine and they show no sign of wear. 100% elimainated the head shake and the ride is noticably more sporty for me as well. Dont have mounting equipment but I did install balance beads and instructed the dealer not to balance them when he mounted them. Love them so far.

 

[Flyguy]

conclusion that the only common factor in both occasions was that I balanced the tires myself. So for now, I am convinced that the cause of the front end shaking is improper balance of the front tire.
Some shops do a less than crappy job at balancing the tires, or their equipment is not adequately calibrated or the place all the weights on the same side of the rim. I do a painstaking static balance of the tire and distribute the weights equally on both sides of the rim to balance it left to right. This seems to make a difference.

If anyone wants to try this, I would like to hear the results.

Nice try. I can understand drawing that conclusion but balancing will not have any effect on a 24"+ diameter tire below 54 mph. When an imbalance problem manifests itself it will occure for a specific interval of usually 6 - 11 mph. There can sometimes be a second frequency vibration in a more limited range but it would be at a faster speed not a slower one. To prove it to yourself mark the position and amount of the front weights then remove them. As you know they are easy to reinstall. Might even try installing them 180 degrees out just for fun. Let us know if you do.

 

[FJRocha]

Nice try. I can understand drawing that conclusion but balancing will not have any effect on a 24"+ diameter tire below 54 mph. When an imbalance problem manifests itself it will occure for a specific interval of usually 6 - 11 mph. There can sometimes be a second frequency vibration in a more limited range but it would be at a faster speed not a slower one. To prove it to yourself mark the position and amount of the front weights then remove them. As you know they are easy to reinstall. Might even try installing them 180 degrees out just for fun. Let us know if you do.

Moment of inertia is directly tied to the geometrical distribution of mass about both sides of a plane. Also, the forces orthogonal to the axis of rotation are directly proportional to the angular velocity of the rotating mass. Therefore, it follows that, the faster the tire spins, the greater the forces will be in a direction perpendicular to the shaft; this causes vibrations at higher speeds (in the vertical direction). However, at slower rotational speeds, the force vectors will be perpendicular to the true symmetry of the mass distribution. If the tire is not balanced in a way that distributes the mass symmetrically to the vertical plane perpendicular to the shaft, then it will produce moments of inertia (torque) vectors in a direction non orthogonal to the axis of rotation, this vector will rotate with the tire forming a cone with the shaft as the axis and cause it to wobble.

Pandora is fixed and I am not about to go and mess it up to prove your point. Pick up a rotational dynamics book and learn about the physics behind tire balancing.

 

[Kevin Daly]

Like so many here my bike developed a VIOLENT headshake on decellerating from 45-50 to 25 mph no braking. I dont mean a wobble, I mean it wanted to eject me as I let it grow to see how hard it would shake.
I am getting a little concern with this so called wobble with tires. Granted this is my first sport touring bike, but I have been ridiing for years and have never encounted this so called shaking!! Is this inherit of sport bikes? I can not imagine that a tire company would take on the liability of producing tires that can cause this type of situation. I would think that their would be many lawyers doing lazy circles waiting to pounce! And if this is a serious problem has anyone heard of anyone getting seriously injured?

I gots to know

fj's are known for having a headshake aka potential tankslapper on decel from 50-35mph. not having cupped tires, having correct inflation, and having correctly-tightened steering head helps to reduce it, but it's still there.

dean

cincinnati

You know I just got to say that i have never had this problem on the FJR I have now run 3 different tire brands (D208's strada's and PR2's) and i have no problems letting go of the bars and coasting down to a crawl; even when the tires are toast. if you are having headshake your are either too heavy in the back (take off the bags and see if that helps some), your suspension is not properly set up (I dont know... perhaps too much front spring preload), and/or you do not maintain tire pressure properly and/or you have worn the tire in a funky way (which usually means you dont maintain the pressure) and/or the tires were not balanced properly. With the exception of a loose steering column, front end shake just doesnt happen on STs by design. Tire pressure should be checked regularly especially just after a new set is put on. Suspension needs to be set up properly; forks and rear shocks dont have all those settings as bling to sucker people into buying the bike, they actually serve a purpose. There are many good threads on how to set up the suspension READ THEM CAREFULLY and experiment. if you plan on making changes and your tires are already ****** up then better to just swap them out for a new set. No sense in trying to fix a problem that is now a permenent part of the tire.

 

[Kevin Daly]

I was actually warned about this by the sales guy when I bought my baby. He also rides an FJR and warned me to keep a close eye on tire pressure as cupping was almost sure to develop even when tire pressure is diligently monitored.
Looks like this is true based on all of your experiences. Tire pressure seems to be related as well. Another reason to keep an eye on that pressure I guess.

I thin you will always get cupping on heavy bikes especially on the front end. especially if you are breaking hard into corners (as you lean the bike over), which puts weight on the front end and scrubbs off rubber, as opposed to breaking befire you enter the corner and accelerating out, which takes weight off the front end. All that said, I have had some (not a lot) cupping on all my front tires and never had a problem with front end shakes.

 

[Kevin Daly]

How many use topcase with side cases??

I have the Yamaha topcase , had it the first day I got the bike. Have had no problems what-so-ever with it. Loaded both sidecases with aprox 17 lbs of crap each, about twice that in the top case and my wife on back 1200 miles trip speeds now and then in the 3 digits...again no problem.

The only issue I have seen is sometimes riding solo some folks have noticed a little instability with all three bags on. This seems to be an issue of aerodynamics, not load. Cranking the windscreen up, or placing a bag on the passenger seat seems to solve this.

KM

KM

With my top case on and empty I notice some instability at high speeds, this is related (I am sure) to areodynamics as you suggest.