Shaking Steering

Hello all,

Looking for a solution for Shaking or Wobbling steering fork. I have had a
number of bikes over the years and this may be semi-normal or not. While
riding I have noticed on some bikes that if you take your hands off the
grips the bike will track nice and straight no problem. (not the smart thing
to do, I know) On others even though NO vibration is felt prior to release
after a few seconds a wobble is started in the fork. Re-grabbing the grips
all is returned to normal.

Some bikes this wobble can get quite violent if left go too long. On one
(GS550) that I had from almost new only started this after about 12,000
miles.

So my question(s) is/are as follows:

Is this due to wear on the fork bearings??

Is this due to a out of balance tire??

Is this due to a bent rim??

Is this due to bad some issue with the forks??

Is this due to all of the above or something else??

And is it an early sign that something is need of repair??

Also what would be the most likely first thing to start the problem.

I am not looking to do stupid tricks on the bike, but if this is a early
warning to something more serious it would be good to know. Not just for me
but to all riders.

Thanks to all that respond.

Les

 

It may be. Have they been adjusted or serviced? Are they
binding? Are they loose or damaged?

Probably not.

It can be. Have the rim checked for runout and/or damage.

Probably not.

It may be caused by a particular tire, or the wear pattern of
that tire due to aggrssive use of the front brake.

It definitely needs to be repaired/adjusted/corrected.

Steering head bearing condition/adjustment, tire wear, tire
inflation.

 

Anything

As you'll see from the above, there are dozens of things that can
affect motorcycle stability. For example, have you got luggage fitted to
the bike? Heavy panniers or (worse) a high-mounted top-box can
drastically change things.

Worn swinging arm bearings or worn wheel bearings could also contribute.

Or it could just be an accumulation of slight wear in several or all of
the above.

Albrecht, I'm afraid, is only addressing one possible cause of the
problem, and even that is cut & pasted and not the result of direct
experience.

As for the old GS550 - remember that is a 1970s design, from an era when
Japanese chassis technology was rudimentary, to say the least.

I've had the sort of wobble you describe on more bikes than I can think
of. The best advice, assuming that you've checked all the above items,
is not to take your hands off the bars.

 

Thanks to all for the quick responses.

It would seem that maybe I should start with the front fork bearing being a
little loose. I am presently riding a 92 GoldWing. And have noticed it as
well.

I have not had it in for any servicing since everything else seems to run
just fine. Except for State Inspection and oil change.

The tire pressure is where it should be as per spec's.

New tires put on just prior to purchase a little about 1 1/2 years ago and
maybe 3000 miles.

Did not check the tire size as yet------------------ but will as soon as I
leave the computer.

Tires do not show any significant wear pattern that some describe.

Thanks again for all the input very helpful.

Later,

Les

 

The problem you have is that a 1500 Wing does not really possess the
inherent stability of, say, a modern sports bike or even sports-tourer.
There is a definite limit to what chassis and tyre technology can
handle, and the Wing is close to it.

But, yes, I'd start at the head races. Check for a notch in the
straight-ahead position, and that the adjustment is correct.

Be aware that, on this bike, changing the races is an utter bitch of a
job. One of the regulars on ukrm took about a week on the task....

 

<snip>

Some bikes will be a bit wobbly when ridden hands off even
when new or in as new condition. OTOH, you need to worry if
the bike changes and gets worse.

The two causes that I have experience of have been worn
steering head bearings and unsuitable tyres.

The tyres were a bit odd. They were OEM and the bike would
wobble as soon as you let go of the handlebars. When they
wore out and I got another tyre type things improved.
As far as I've been able to understand this, every tyre has a
fundamental stiffness and damping (correct inflation pressure
assumed) that will influence if or when low speed wobble
occurs and this is more important than tread wear.

 

WTF? I've done and seen a lot of low speed riding but this was a new one.
What sort of bikes behave like that?

 

Only one with severely over-tightened head races, in my experience.

Nothing to see here: he's talking bollocks again.

 

It's a really weird feeling, isn't it? The thing sort of rocks and rolls
from side to side. Only had it happen once when, like you, I
accidentally over-tightened a new set of taper roller bearings I'd just
fitted.

 

Anyone else here had a bike with friction steering damper? They went
out of fashion sometime in the 60's. Weird things but they sort of
worked on motorways and other fairly straight roads.
But forgetting all about it and riding into a roundabout without
slacking of on the adjustment knob was "interesting".

 

You might increase the tire pressure by a couple pounds just
to test the behavior even if you believe they're set per specs.

I'm also a little leary of 15 year old manufacturers tire specs.
I'd rather trust a tire mfrs spec.

After experimenting with tires, I agree that the steering
head is a good place to check. On a bike that age, wheel
bearings might stand a quick inspection too.

 

No, sorry.

Lots and lots of bikes have weaved at high speed - you were talking
about low speed weaves.

Still high speed weaves. Not low speed.

Well, what do you expect? If you fit knobbly tyres and use them on the
road? If you fitted slick tyres to it, would you expect it to perform
as well off-road?

They are - I had them on my Ducati. I'm at a loss to understand why
they didn't work on an FZR Thou, but stranger things have happened.

Ah, so you fitted a tyre with a different section to that recommended?
What did you expect?

Rubbish - a lot of manufacturers have fitted unsuitable tyres as OE
simpoly because they were cheap. My Ducati, about as sporty a bike as
you could find, came fitted with Michelin Macadams - a rock-hard
touring tyre.

And consider this: tyre technology evolves. Doyou really , really
think that (say) it's better to fit tyres that were OE to (say) a five-
year old bike instead of new tyres that have benefited from five
years' worth of development?

Look, you started talking about low speed weaves and to 'prove your
point' gave examples of a high speed weave on an antique Jap bike and
a low-speed weave when you fitted totally unsuitable tyres to a dirt
bike. This is irrelevant.

You are posting fatuous and potentially dangerous nonsense to a
technical newsgroup. If, as you proclaim, your advice is intended to
help newbies, then the above is not the way to do it.

 

Yes, this is good advice.

Oh yes.

 

You make it sound like Honda put bias ply tires on the ST1100 instead of the
radials it was designed for just to save a couple of bucks. :0b Difference
in performance is amazing.[/QUOTE]

Oh yes

I remember the rear tyre was still legal at 9000 miles, and I couldn't
wait any longer and junked them both. I have a vague memory that the
Yamaha YZF750 was originally fitted with something similar, but I
could be wrong. God knows what Ducati was doing: I have a vision of a
French tyre salesman scoring a good cheap bulk order.....

 

My old 1978 airhead BMW had one.

 

<snip>

Sooo... low speed wiggles are at 100 mph. At what speed do you start to talk
about high speed wobble? Mach 1.5?

 

????


They switched to hydraulic dampers in 1974. The knob repositioned the damper's tree mount to alter
the resistance.

 

They did? Could have sworn it was friction. TGhanks.

 

One thing we can be certain of-- there _was_ a knob on your bike.

 

Ha-bleedin'-ha.....