Wobble and weave

Been through many of them the last 40+ years. When it was happening no way would I try to lay down it happens too fast. I loosen my grip on the handlebars and use my body to bring it back under control. Naturally I'd lean forward a little bit and back off the throttle SLOWLY until it stopped. Last time it happened it was due to a underinflated front tire. This time it was at 80 while I was about to pass. Good thing I didn't. 
Steve

That video makes this 145 lb man want to get a steering damper. 

YUP 

wrote:

Here is a example

Would you go to that extreme to get your Vincent to do 150MPH?  
I guess it made him famous!

Mike
 

Like I said, I won't ride any motorcycle without a steering damper.   End of question.

 

 

In a swimming suit with a steering damper????

Mike

Wobbles are strange events and one must determine what the wobble is being caused by which in some cases is quite difficult.  A wobble on a bike can be caused by many things not the least of which is how the bike is loaded.  Want to make life interesting?  Start adding weight behind the rear axle and see what happens to your ride.  A steering damper is a great add-on that many swear by but you have to use them wisely.  A steering damper can cover up other problems though such as worn bearings, defective tires or wheels, loose swingarm etc.  One of the most interesting bits of motorcycling history was with the early Police Model Kawasaki's that had a real issue with high speed stability.  Everyone that was using those bikes knew there was an issue but no one had a real good idea how to fix it at the time, so Kawasaki issued a directive not to operate a police model over 55 mph, until they found a fix.  My old agency was using a couple of early police Kawasaki's at the time and somewhere I my pile of stuff I have a copy of the warning notice.  I could be wrong on the speed limit imposed but it was close to that.  These were the old windshield only bikes and weren't fairing equipped yet.  The wobble usually took place when you hit a bump or set of railroad tracks and unloaded the front end and quickly hit the throttle before the front end settled down.  As a result Kawasaki started using their swinging radio carrier which I never quite understood, but I only rode part time back then and didn't spend enough time in the saddle to get familiar with the so called fix.  I experienced something very similar riding Harley FL police models later on.  I discovered that when these wobbles or more appropriately oscillations started the easiest quickest way to calm things down was to get more weight on the front wheel by moving as far forward as I could.  This usually helped but it wasn't the end all cure. 

Looking back on it years after the fact while training new police riders it became pretty obvious that one of the root causes was improper loading of the motorcycle especially adding weight on or behind the rear axle, or excess weight to one side of the bike.  Remember it's a fine line when you put weight near or beyond the rear axle as weight starts coming off the front.  There was a point in time where police departments joined the motorcycle bandwagon in haste because gasoline was really expensive and administrators thought purchasing and using motorcycles would be a great way to save money which it was.  Unfortunately they didn't have a clue about using motors and made up their own rules about outfitting their motors without consulting those in the know.  In essence they were trying to make a car out of a motorcycle and it didn't work.  The end result was police motorcycles soon lost their attraction and were relegated to the back of the police garage or sold off at auctions for pennies on the dollar.  I also saw a lot of misinformation put out about how to handle wobbles and such and this only added to the problem and I think led to several crashes that didn't need to happen.  Anyone remember the old "just power through the wobble" cure?  Or "just quickly roll of the throttle"?  How about "damn the torpedoes, straight ahead" philosophy?  

Things are different today and much about motorcycle dynamics has been studied and learned.  Not all motorcycles are equal and certain bikes are used in ways never envisioned by their designers.  Show me one motorcycle company that designs their authority motorcycles to do an honest 16' turn and I will be shocked, yet police riders do them all the time.  Just remember there usually isn't one absolute cure for a wobble or oscillation on a motorcycle and one must use caution not to mask it with a band-aid.

Rick H.  

Rick,  I was involved in the Kawasaki Police Bike Wobble Saga in the early 80s.  I believe at the time Kawasaki was involved in, or had lost a class-action law suit over the situation. I was included in a Nationwide Campaign set up by KMC in CA and KHI to visit Police Depts. and inspect and sometimes work on their bikes. 
The spectrum of how poorly to how well they were maintained was pretty dramatic. I believe Kawasaki's stance was the main issue was bikes that were poorly maintained or had been altered from standard configuration as in non- standard tires, or adding too much weight where it didn't belong. I never did know if the campaign was to gather evidence, the result of a settlement or just a good will gesture on Kawasaki's part. It was fine entertainment for me traveling around with a team of KMC and Japanese guys and meeting Motorcycle cops.

Mike

The worst wobbles I had was in the 70's with the bike naked in stock trim. The Z1's were well known to have high speed wobbles due to weak frames and swing arms. The brace under the steering head always had cracks in the same spots at the cooler bolt holes. There was a cheesy fix for that I figured to be just plain stupid. A small bolt on bracket.   They were offering new bronze swing arm bushings and if you REALLY wanted to be cool you could install a needle bearing kit for $250. Should have been there anyway.   First thing I did was to beef up the steering head bracket covering the cracks, gusset the backbones and installed the new bushings  It was better but it was still prone to wobbles. With the new KZ's they quietly beefed up the frames and added a gusset under the steering head the Z1's didn't have and went on to business as usual. It's obvious they knew of the problems but decided to ignore it. Early KZP's brought the issues to light but they did as little as possible, they just redesigned the swing arms along with a few other things. To this day aftermarket has been addressing these issues with gusset kits, custom swing arms, etc. The biggest improvement is the late model KZP swing arm that is 1 1/2" longer and modern pivot bearings. It now shows how weak the front end is. That I'll be addressing next.
Steve    

Here's my solution.
Me and my buds were going way to fast to allow any  wobbles.
 I experienced  wobble on my 750 Triple H2 and didnt want  to ever go thru that again 
So we all gusseted  our frames, Roller bearings in steering head, , steering dampners ( 2 on mine )  and tight bearings in the swing arms, all back in the day
Since then I added the fork brace and then had Les Holt @ PDM build me these trick  triple trees
My Bike Dont Wobble and I feel the effort was  worth it. No worries at speed
Dave

 

This time it was my fault.
Steve

This is an example of what Steve was speaking to.  You can see that both bolt holes for the oil cooler have cracked.  On the right side (left side from rider position) you can see how the crack went into the frame and was almost all the way around the downtube.  

There were several fixes to this problem.  The first was what Steve mentioned...a brace was added to the frame across the oil cooler holes.  It was a little chicken shit but it was effective in stopping the flexing that would eventually lead to the cracks.  The second fix was to not drill the holes.  My other Z1B(Jan/75 build) didn't have the holes.  If you wanted an oil cooler you had the holes drilled when the cooler was installed.  The third fix was a total re-design of the gusset between the down tubes to add some strength.  This was done on the KZ900 bikes.

The method of failure was vibration induced fatigue failure.  It started at the bolt holes because that was where the frame stresses were concentrated to the highest amount.  When a crack developed it would continue across the gusset and eventually work into the frame.  The PO of my bike was lucky he didn't have a frame failure while riding.  He had souped the bike up pretty good and I suspect he rode it hard.