Bonneville America Forums Forums Technical Forums General Tech Front end wobble

My Speedy has developed a very bad front end wobble, if you take one hand off the bars it shakes violently from side to side?

I have looked over the bike on the hoist and can't "see" the problem.

Front wheel spins free and true.
Brakes are not binding.
Shockies appear to be functioning normally.
Balance weights are intact on the wheel.
No abnormal wear on the tyre.
Tyre pressure good.

Can anybody give me a clue where to look? It has been getting progressively worse and is more noticeable with a pillion on...

Regards.......Binnsy

Had that problem with Wendys bike,turned out to be the tire. I changed it and no more wobble. Also check rear wheel alignment,steering head bearings,and fork alignment among a few other possible causes but I think those probably the most likely giving what you already checked.

Without knowing any background, miles on the bike, miles on the tires, did you hit a curb, etc... it's hard to say.
I've had the same problem several times, and it's always been tire wear or air pressure. I have an America, and I've been running Avons for the last 18000 miles or so and although they stick like glue, they also "cup" very easily. A panic stop skid will put a flat spot on your tire that you may not notice but will affect the ride as the tire continues to wear and scrub unevenly. Rear or front.
Put the bike on a lift and run your hand over the tread. You can feel the cupping even though the tire looks good...

There is a big thread about this some where. It has become the infamous front end wobble saga of the triumph twins all kinds of ideas usually a new tyre and re balance fixes the problem

I'm still on the OEM Metzlers at 20K, and the wobble seems to come and go. I'd also want to believe the front tire is part of the issue, and perhaps the fork rake angle sets off a harmonic vibration? Kind of like sticking a big old tuning fork out in front? Don't know for sure.

To further regale [read-bore] you with yet another truck driving story from my days of yore: I used to haul Fruehauf J model dry bulk trailers (aka cement tankers.) When loaded at around 45 MPH, the entire 80,000 lb vehicle would find a harmonic and jump up and down around 1/2 inch, at say, 2 or 3 cycles per second. With the inertia of 40 tons hopping up & down, it felt more like it was jumping up & down a half a foot or so. Some flat beds will do this too, if you load them just so. What does that have to do with anything? I'm not sure, but since I've finished my first double coffee of the day, the keyboard is at my mercy.

See also - traffic jams on a suspension bridge, where the entire 4,000 foot long road deck mass is hopping up and down an inch or three. I hate it when that happens...

Check the balance...I have like a pound of weights on both of my bikes...and if the balance isn't right, she will wobble....

Mine does it too. New front tire fixes it for about 1000-1500 miles then it does it again.

Quote:

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My Speedy has developed a very bad front end wobble

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I have found that the wobble syndrome first occurred after installing the second generation Metz on the front. After the second replacement of a new front and again experiencing wobble, I did some research. It appears to me that the recommended pressure for use on the Speedie (by Metzler) has increased from the original tyres 36psi to 40 psi. I've found 40 psi to deliver an unacceptably hard ride. I've done some experimentation and have found that 38psi is just about border-line in that the wobble is NEARLY gone and the ride is NEARLY acceptable. In short, play with your pressure. Note: once you've cupped - the damage may well be done and wobble most likely can't be addressed with pressure.

Although the front tire is most likely the problem, the tail can wag the dog, so check the rear as thoroughly as you did the front. When my Speedy started to wobble, a new front skin fixed it right up.

The Speedy and America's geomentry lends it's self to this type of wobble. IMHO the main causes are rear tire mis-alignment, front tire wear and front wheel balancing. In rare cases it can be loose triple tree or triple tree bearings.

"Resetting" my forks and adjusting the rear wheel so that it's square down to the millimeter is what fixed my wobble.

i had this problem after installing avon front tire, it cupped (bad) replaced with dunlop, problem gone

Harmonics.

Bit more info'

I recently had Avon Venoms fitted, no wobble when new but now a couple of thousand K's later....Tyres stick like poop to a blanket, love em.

I have played the tyre pressure game, got up to 40psi up front and wobble not as bad. Didn't look at the rear? didn't think that could affect the front end..

I will have a close look at both tyres on the weekend, looks like rain anyway..

Thanks for all your help team

Regards........Binnsy

Does it wobble all the time or at certain speeds or decel, etc....?

Wobbles all the time but varies in intensity. At about 80 the wobble is fast and easy to control, as you slow down the wobble becomes more intense and I have to hang on, not good on mountain roads...

I am sorta going in the direction that the tyre has a problem. I will probably run down to my local performance shop (these guys race bikes) and let them have a look.

I suppose I could live with it until I trash the tyre but it is peacing me OFF!

Sounds to me like the tire too.

I'm with you Fishercat. The geometry is a contributor that we must live with. Anyway, someone replied to a post of mine in a similar thread long ago that I shouldn't be riding with my hands off of the bars. Nuff said.