death wobble

[RaYzerman19]

Since you say relatively new tire, I am wondering if there's an alignment issue. Similar to the procedure for Honda ST's and GL's, the Yammy Service Manual says to jounce the front end before torquing the front axle, and to tighten the pinch bolts in a certain order..... might seem a bit anal and maybe there's something to be gained.

I would also check wheel and tire runout, both radial and axial.

 

[jameswilson]

Tire. When my 07 was new no wobble at 500 miles a wobble developed, after agrument the dealer changed the tire, no more wobble

 

[Duff]

Tire, with any amount of wear on it, can cause this between 50 and 40 on a hands-free coast down.

Tire pressure, typicaly too low, causes this to happen faster.

LOADING can also cause this. If the front end is light, it will wobble. I have discovered this when loaded heavy to the rear for a trip. It also increases if I let go and "lean" back to take weight off the front.

If your front wheel does not "knock" when suspended from the ground and pulled front to back, the head bearings are probably fine. The wheel bearings are also probably fine. Check tire wear, tire pressure (39-40) and loading... and "don't let go".

 

[JamesK]

If you saw how bad the bars shake after a couple seconds you'd know why I called it a death wabble. I'm a dirt biker from way back and little crap doesn't bother me.

All bikes have a resonant frequency to their front ends that is divergent at a certain key speed, typically around 40mph. It's a random thing and while new tires, perfect steering head bearings, careful suspension setup, perfect wheel alignment, correct tire pressures, and proper weight distribution, the problem is minimized but it is probably still there. If a bike appears to be steady, it is often because it decels through the critical speed fast enough for the wobble not to develop. Try throttle locking any bike at the exact resonant speed, take your hands off the bars, and they'll all develop the wobble eventually. Arms are required steering dampers.

If the wobble develops very quickly and violently, I'd bet on a defective front tire, then work down the standard checklist of stuff. Beyond this, this is something that is a lot easier to live with than to tear your hair out about.

- Mark

I'm just curious why I don't recall ever seeing any mention of steering dampeners for the FJR? Most other bikes seem to have a dampener but not the FJR.

 

[Happy Rider]

I agree with the front tire being the issue. My 09 does the same thing when the front tire gets some miles on it. If I do a lot of mixed miles with plenty of curves and straight riding the tire keeps a nice round profile and I get very little or no wobble on hands free decel around 50 mph. If I let the front tire get a flat spot down the middle the wobble will develop on hands free decel at around 50. I've seen this happen on the last three sets of front tires. Every time a new front tire goes on it goes away and the bike has beautifully light steering. If I do what I'm suppose to and keep my hands on the bars I feel no wobble in the bars even with a badly warn front tire.

 

[charismaticmegafauna]

I'm just curious why I don't recall ever seeing any mention of steering dampeners for the FJR? Most other bikes seem to have a dampener but not the FJR.

(I think?) Damping motorcycle front end oscillations requires high speed oscillations to damp. The relatively low speed oscillations that frequent some touring bikes would be difficult to damp with a hydraulic type damping mechanism -- it'd need to be unduly stiff.

Short-coupled high-powered race-replica motorcycles often have steering dampers because the quick steering can sometimes get too quick and become un-nerving for the rider -- a damper keeps any 'head-shake' under control (so as to not up-set someone who was not prepared/looking for it).

I think if one really wants to rid a bike of 40~50 MPH de-cel wobble?, you need to address either/both weight distribution or chassis geometry. Weight distribution is the easier of the two -- take the 2 bowling balls out of your tourpak (I don't know where to recco to put them... ).

Changing chassis geometry gets a little more involved -- but, shorter rear susp. linkage dogbones would be a good place to start (raise the back end, changes the front geometry some, provides more weight bias forward...).

 

[Bounce]

I'm just curious why I don't recall ever seeing any mention of steering dampeners for the FJR? Most other bikes seem to have a dampener but not the FJR.

define "most"

125cc and smaller bike (including scooter) make up the majority of bikessold worldwide. Few, if any, include dampers.

 

[dcarver]

Realizing that 'death wobble' severity is entirely in the stain of the beholder, I'll offer up that since I replaced the stock head bearings with rollers I've not had any head shake / wobble, even across mismatched tires of brands and compounds. And I run my tires till cords if at all possible, e.g. not leaving on a trip.

I'm not sure if your experience of a 'wobble' are similar to the decel head shake I used to have. Just another .02 - good luck..

 

[copron]

It's the head bearings......ask almost anyone who has put a lot of miles on a VTX 1300 or a Goldwing........most riders of those bikes replace the stock ball bearings with roller bearings and the problem goes away and the wear on the front tire doesn't effect it. Both of those bikes have the exact problems you describe.

Nah....it's the tires.

It's Yamaha's secret, patented way of telling you it's time to change the front rubber.

Brand new Azaro...no wobble. 6800 mile Azaro, decel shake @ 50mph.

Brand new Storm...no wobble. 10,500 mile Storm, decel shake @ 50mph.

2nd brand new Storm...no wobble. 12,300 mile Storm, decel shake @ 50mph.

Brand new PR2...no wobble. 6,000 mile PR2...not worn enough yet. No wobble.

I've never touched my steering head bearings. Bad tires = wobble. Good tires = no wobble.

If it was steering head bearings, the bike would always wobble. It doesn't. So it isn't.

Ball bearings > roller bearings doesn't get rid of the problem. It simply masks it, like a poor-man's steering dampener.

The problem is, masking a worn-out or crappy tire is asking for REAL trouble.

You really need to adjust those head bearings, a decel wobble in the 45-50 mph range is almost always attributable to maladjusted head bearings. The death wobble ( high speed wobble/tankslapper) is a whole different ball game.

 

[RadioHowie]

You really need to adjust those head bearings, a decel wobble in the 45-50 mph range is almost always attributable to maladjusted head bearings. The death wobble ( high speed wobble/tankslapper) is a whole different ball game.

Dude, perhaps you didn't hear me......

[SIZE=18pt]Brand new Azaro...no wobble. 6800 mile Azaro, decel shake @ 50mph.[/SIZE]

Brand new Storm...no wobble. 10,500 mile Storm, decel shake @ 50mph.

2nd brand new Storm...no wobble. 12,300 mile Storm, decel shake @ 50mph.

Brand new PR2...no wobble. 6,000 mile PR2...not worn enough yet. No wobble.

 

[dcarver]

ouch

 

[chivvalry]

LOL... at risk of a RadioHowie blast...

I had a Kawi Eliminator (back in the day those had real displacements) with a blown front fork seal that had a really bad decel wobble...

...but it could have been the tire.

 

[RadioHowie]

LOL... at risk of a RadioHowie blast...

[SIZE=24pt]FYYFF!!![/SIZE]

:wub:

 

[chivvalry]

LMAO

 

[majicmaker]

LMAO

+1 :rofl:

 

[markjenn]

I'm just curious why I don't recall ever seeing any mention of steering dampeners for the FJR? Most other bikes seem to have a dampener but not the FJR.

Steering dampers might slow down the no-hands 40mph "wobble" but they won't prevent it. And the FJR (and heavy touring-oriented bikes like it) typically have conservative-enough steering (rake, trail, etc.) with enough inherent stability that they don't require dampers. Dampers are spec'ed more to stop the much more violent "tank slapper" type of wobble that typically occurs when you land a wheelie slight crossed up on a hair-trigger, relatively-unstable sportbike.

Steering dampers are band-aids to restore stability to bikes that have had their steering sharpened to make their handling responsive. You don't want one unless you need it and in stock config, the FJR doesn't.

- Mark

 

[Bustanut joker]

Sometimes when I get drunk too early say 7am..... (normally I wait till 9:30 in the am) I tend to wobble to the commode and while hugging it pray for death

Shit! nevermind.... that's a wobble death.

Damned dyslexia....

:jester:

 

[RadioHowie]

Sometimes when I get drunk too early say 7am..... (normally I wait till 9:30 in the am) I tend to wobble to the commode and while hugging it pray for death Shit! nevermind.... that's a wobble death.

Damned dyslexia....

:jester:

It's shit like this that makes proud to be your friend.

....and yes, I have NO standards. :finger:

 

[beemerdons]

Sometimes when I get drunk too early say 7am..... (normally I wait till 9:30 in the am) I tend to wobble to the commode and while hugging it pray for death Shit! nevermind.... that's a wobble death.

Damned dyslexia....

:jester:

It's shit like this that makes proud to be your friend.

....and yes, I have NO standards. :finger:

+1,000! One Hundred Times GUNNY!!!!!

 

[Bustanut joker]

Hey! You homos stop with the Hijaks!! I was serious here..

:fuck:

:jester: