Front Wobble on Decel

So a while back I posted that I experienced a front end wobble on deceleration one day when I took both hands of the bars to zip up my jacket. My tires were worn so I put a new set on. Wobble was still there but not as bad. This is been bugging me for about a yr now. Finally I performed road test with the following changes.

Air press at 30 psi front and 35 rear
Top box on but empty
Results: Huge wobble.

Next removed top box
Results: No change.

Next put top box back on and raised front tire pressure to 35 psi
Results: Wobble almost gone!!!

Next took top box off again
Results: Wobble completely gone!!!!!

So I feel the problem is a combination of soft sidewalls and extended attachments up high and off the back. The SW just doesn't like it.

Thank you for posting this, Toolman. Great info to have.

We all benefit from shared information.

Tim

35 psi in the front? I think it might pay to check the state of your head bearings...

Presumably the wheel is balanced ?
Check tyre for eneven wear pattern.
For topbox fitment, try fitting heavier handlebar end weights (sometimes supplied with the box)

Toolman: Further to your observations re front end wobble, I wonder how much your million dollar custom shocks play into this (i.e. decel weight shift or the lack of it)?

The triple tree is a single yoke on Silverwing scooters. While fine in normal use it tends to protest under certain conditions. My Silverwing had a leaking fork seal and worn front tire when I purchased it. Wobbled like crazy when slowing down. Got a new front tire and rebuilt the fork seals (OEM oil and springs) and rebuilt the headset bearings. Was greatly improved afterwards. Tire pressure is very important as is proper weight loading. Mine has a medium sized GIVI top box.

Strictly speaking (or writing) there is no triple tree on a Silver Wing scooter. The triple in triple tree comes from the way most motorcycle forks are built. There are three tubes joined usually by the top plate and a lower triangular plate that the steering head tube and the upper end of the shock tube are held togther. The Silver Wing's fork is much like the nose wheel on aircraft. A single shaft through the head bearings to the handle bars and a casting where the fork tubes and steering shaft tube meet. Plenty strong for the loads put on it.

The Goldwing motorcycle have a similar head shake usually only noticed by allowing the bike to decelerate through 35 mph where the head shake usually occurs. It's similar on the SW, it's not a violent wobblie like the dangerous ones some Harley bikes had at high speed. At 35mph or so there just isn't that much energy in the system to get violent. Usually one hand lightly on a grip will stop or prevent it.

Now if anyone is looking for some real tank slapping wobbling try a '49 Triumph 650 with the friction knob on the fork not screwed down snugly at road speeds. Downright scary.

I can't confess to be an expert on this subject but I thought it was all down to the small wheels on the SW. I have a new front wheel which is balanced and a new tyre...it wobbles a bit at certain decel speeds when I let go of the handlebars. I thought it was normal!

On a Goldwing a well balanced new front tire often eliminated the 35mph deceleration head shake....
for awhile. My BMW C650 scooter also had the same symptom as does my current Silver Wing. On both the Goldwing and Silverwing I've experimented by going hands off and slapping one or the other grips at varying speeds. It takes nerve at the higher speeds but I did it. I've never found a violent tank slapper wobble like the Harleys were afflicted with. Those were downright dangerous because they happened at high speed which meant there was a lot more energy in the wobble. Something like that could result in disintegration of the fork followed by the rest of the bike and rider.

I've never heard of anyone with a Honda product in good condition having a dangerous wobble. As an experiment when you do get a quiver in the fork just put one hand or a couple of fingers on the grip and you will find it quits immediately.

exavid wrote:

As an experiment when you do get a quiver in the fork just put one hand or a couple of fingers on the grip and you will find it quits immediately.

When I experimented with that wobble I found that by resting my index finger on either of the hand grips the wobble stopped. Unless you're getting wobble with both hands on the bars, don't worry about it. As I said, I think it's normal for this type of design.

Solution: Don't let go of the handlebars

That kind of head shake is not unusual in bikes with fairings. My previous two Silver Wings did it as well as my BMW C650GT. It doesn't seem to be two threatening and doesn't seem to take any effort to stop it.

Early Goldwings had a pretty impressive headshake. Honda solved it with a heavy weight on the frame which would oscillate out of phase with the head shake. Not too sophisticated but it fixed the problem on that bike.

Heavier bar end weights will often help with the wobble or head shake that happens if you like to load the top case. You can find some that weigh about a pound each, and these usually make it go away. They can also make the ride a lot smoother in general.

My previous owner installed heavier weights what did not look too nice, but he kept the old ones.
My new owner did not like what he saw, took a dremel, cut off the inside part of the new ones , combined the old ones with the new ones and put a black O-ring in between to hide the little gap.
Result, Bigger, Longer and Cut (South Park movie reference)
picture 2 is before the repainting.

One risk of adding weights to the bar ends is that there still will be a wobble frequency. It may not be at the same speed and conditions as before but there will still be a resonant point and the heavier the bard ends the more energy that can be absorbed by the wobble which could make some unusual wobble responses at an unexpected speed.

And to think most motorcycles used to come with friction type steering dampeners!! Prevented or al most eliminated de-cel wobble and almost 100% necessary for sidecar use.

Yes, but it's a long time ago since they were. I remember owning a couple of 1970's 250cc MZ's with friction type steering dampers. I never used them and never had to, they were installed for when owners decided to fit the MZ Super Elastik sidecar.

I can't remember any motorcycle or maxi scooter I've owned having handlebar shakes and wobbles, apart from one isolated occasion in the Eighties coming back from a miserably cold Dragon Rally in North Wales.

I had a front wheel puncture on a motorway on the way home As the tubed tyre suddenly went flat and my sphincter puckered up, I had to really wrestle with the the handlebars to get safely over onto what we call 'the hard shoulder'.   .

All two wheeled single track bikes have a natural wobble. If you have ever seen a race in the rain, you could see the trail of water making a shallow s pattern of the water on the track when the bikes accelerate. With the little wheels on the SW and sort of long wheelbase it is exacerbated and depending on the weight combo and tire pressure of our individual machines, wobblyness may happen. Since it stops when your hands are on the grips, I don't see a major problem. I had a sidecar combo for a while and only at low speeds did it wobble on deceleration. Pretty normal. The most horrible example is what happened to Meldrew after a blowout .

Sidecar out fit set up properly....has steering damper. Since US has no real safety standards for such things, most in US do not.

Hiyo wrote:

All two wheeled single track bikes have a natural wobble. If you have ever seen a race in the rain, you could see the trail of water making a shallow s pattern of the water on the track when the bikes accelerate. With the little wheels on the SW and sort of long wheelbase it is exacerbated and depending on the weight combo and tire pressure of our individual machines, wobblyness may happen. Since it stops when your hands are on the grips, I don't see a major problem. I had a sidecar combo for a while and only at low speeds did it wobble on deceleration. Pretty normal. The most horrible example is what happened to Meldrew after a blowout .

I should have mentioned once on the motorway hard shoulder, the wobble got so bad the MZ finally spat me off and over we both went. This being back before riding suits were fitted with armour I suffered a badly grazed arm and bruised my shoulder.

Luckily a couple on a motorcyclist also riding home from the rally and following me stopped to help. The rider skillfully removed the front wheel and fitted my spare front inner tube for which I was very grateful for.

I had a long ride home home with a fairing as grazed as my arm and a broken screen.

Yikes, wasn't a good trip that day. Glad you made it through. Never had a damper on my rig. Some folks are saying it's necessary, but properly set up it was just fine. Can't say how a blowout would be however..
.

It's pretty hard to predict exactly how a bike will respond to a blow out. Every type of tire is a bit different. It might be that the older non-radial tire might have performed better in such an event. They had much stiffer sidewalls which might have helped the situation. Radials are more prone to more of less disintegrate once they go flat. I've seen a car with a radial that went flat and when the car got off the to the side of the road it looked more like a snarled fishing reel than a tire.

No decal wobble at this speed.
Max speed screen shot.