Topic: Speed wobble

[Nidhoggr]

So after finally getting to take the bike on a highway, I noticed the bike vibrates heavily and has a SLIGHT wobble at excess of 45-55 mph.  Has anyone else experienced this?

It seems to stop when i shift to a higher gear.

[seanbarney41]

these symptoms are caused by many things...first and easiest to look at is your tires...do they need to be replaced?..are they round?...wheels need balancing?

[Nidhoggr]

these symptoms are caused by many things...first and easiest to look at is your tires...do they need to be replaced?..are they round?...wheels need balancing?

Brand spanking new

[mrbreeze]

Wheels outa round,bad wheel, steering head bearings. Swingarm bushings shot. Need to do some investigating. Could just be like mentioned....need wheels balanced. Are the new tires seated correctly on the rims?

[seanbarney41]

next, I would say get a service manual and perform the steering head bearing adjustment...my bike had a wobble when I first got it and this adjustement fixed it right up!

[Grabcon]

My experience is that it comes down to wheels and tires. Are the wheels true and are the spokes of proper tightness. This makes sure the wheel is round and straight. Potentially new tubes and everything must be balanced after tire mounting.

If this does not solve the problem are the wheels in alignment? Are all spacers in the right spot and the front axle put in the appropriate side. They are easy to flip and put in from the wrong side. This causes misalignment, you would most likely notice that the brake does not fit right.

Are the neck bearings in good condition and is the neck torqued properly? Is there the right amount of fork oil in the forks?

[Anti-Johnny]

I'm in the middle of hunting my own high speed issues. I replaced my tires, rebuilt forks, and replaced steering bearings with tapered. The bearings need to be tightened, as there is some up and down play. So now I am not sure. I am hoping to get that tightened this weekend.

The spacers? what do you mean by that? I need to go through the shop manual and check to see the information on the axle placement and the steering bearing adjustment. As these are new information to me.

Also need to figure out how to set my bike up to check trueness and roundness.

Anyway, I'm in the same boat as you brother.

[dave500]

flat spot on a rim,maybe two or three spokes wide?,check the rim run out and the spoke tension,if you can tighten any dull sounding spokes do it evenly,tap each one and make a texta(sharpie)mark on the dull ones,then try to tighten them a little at a time evenly,if a few are real dull do it with the tyres deflated,if the spokes will turn that is.

[Kong]

Bent rims and rims out of true do not cause wobbles, they cause vibrations.  Those vibrations may be unnerving, but they will not put you in any particular danger.  A badly dented rim will cause something like a wobble, though rarely very bad, when you are way leaned over in a turn.   Speed wobbles are an entirely different matter and they are always caused by one thing and one thing only - for some reason at some conditions the front rear wheels are trying to steer the bike in different directions at the same time while the steering geometry constantly tries to straighten it.  While this could be cause by improper alignment more often it is caused by worn or very lose (never tight) steering or suspension components - chief among them steering bearings, then swing arm bushings, and then wheel bearings.  Problems with wheel bearings can also be mimicked by lose axle nuts or improper spacers. 

[Bido]

It took me quite a while to get rid of that wobble at around 45. I replaced the swingarm bushings with brass, replaced the steering head bearings with a kit from Allballs, new tires I used Metzler Lazertec front and rear made sure that the wheels were properly aligned. Last but not least I used Dyna Beads. I had the wheels balanced before I tried the Dyna Beads and there was a slight bounce around 45 after using the beads it is nice and smooth. I know there are a lot of pros and cons about Dyna Beads but they worked for me. Also check you tire air pressure.

Good Luck
Bido

[Nidhoggr]

Bent rims and rims out of true do not cause wobbles, they cause vibrations.  Those vibrations may be unnerving, but they will not put you in any particular danger.  A badly dented rim will cause something like a wobble, though rarely very bad, when you are way leaned over in a turn.   Speed wobbles are an entirely different matter and they are always caused by one thing and one thing only - for some reason at some conditions the front rear wheels are trying to steer the bike in different directions at the same time while the steering geometry constantly tries to straighten it.  While this could be cause by improper alignment more often it is caused by worn or very lose (never tight) steering or suspension components - chief among them steering bearings, then swing arm bushings, and then wheel bearings.  Problems with wheel bearings can also be mimicked by lose axle nuts or improper spacers. 

Well that was definitely informative. Thank you! This is my first bike so I am still getting used to all the finer points of things.  I'm gonna have my mechanic friend give it a once-over to see what could be causing it.