headshake on deceleration

[Guest]

Just really in the last few weeks gotten time to start riding a GS1150ES I bought some time ago. I`ve got some new rubber on the way. In the meantime I have been riding a little(tires are not that bad although fairly worn). I have noticed that I have a moderate headshake when slowing down from moderate speeds. It only happens when I am loosely holding the bars and doesn`t do it everytime. Guess my question is is the rubber going to stop this or do I need start looking at steering head bearings ,etc. This is a low mileage bike so wear is not a issue I think. I have already serviced the forks and it shakes without the brakes. Guess I`m also wondering if this is common to the 1150. I noticed my hayabusa`s had a large steering stablizer stock. BTW the front is a metzler(2/3 worn out). Thanks for some good opinions!

[Joe Nardy]

I have no experience with the GS1150 but I can say that worn tires, and even type of tires, can have a huge effect on headshake. I have replaced tires that didn't seem seriously worn and have had great improvements in handling and headshake. I also had a set of new Dunlop (GT501's I think) on my '88 Hurricane 1000 that induced a terrible headshake. I replaced them with Metzeler MEZ4's and the headshake was gone. I'd definitely try tires before anything else.

Joe

[lhanscom]

Mine will do that very slightly. In order to even notice it I pretty much have to have my hands off the bars. Since I ride with my hands on the bars most of the time, it's not a big problem. This is also negated if I turn my stabilizer up a bit. I currently have the Dunlop 501 up front.

[robinjo]

My 1100 also does this but only when the rear tire is below 30 psi (normal setting is 39) on deceleration from about 50 mph, air up the rear and it's gone. My front tire is still good, rear is about halfway. I hope this is comparable to your 16 incher though. What tires are you getting?

[Anonymous]

I have an 86 1150 efe, and I have the same problem with mine...
Last year and the year before my forkseals and head bearings were just barely good enough to pass safety so I figured that was the cause of the disturbing headshakes on decceleration and when I was ajusting my helmet and was only holding on with one hand...
But this year the old girl wouldnt pass without the new seals and bearings and new rubber front and back, so I figured that the problem would be a thing of the past, but unfortunatly I was sadly mistaken, the shakes are still there and they are as random as anything I've ever seen...
Sometimes I'll be slowing down and take one hand off the bar to fix my mirror or adjust my helmet and the damn thing will shake so badd it almost throws me right off...then I'll test out the shakes and just loosely hold onto her as I slowdown...and nothin, smooth as silk.
Its a strange ghost I have...and unfortunatly I have no answers...but the 1150 is said to be a dangerous handler and I even heard they stopped selling them in Australia due to their horrible handeling...Bar end weights supposedly can do wonders, but I've got a set on and they arent doin a whole lot....
I'd love to know a solution...hopefully there is one out there...
:? :? :?

[Joe Nardy]

I remember years ago reading that almost any bike will shake its head around 30-40 mph when decelerating if there is no pressure on the handlebars. This is exaggerated by weight towards the rear of the bike, especially up high, like a top mount trunk. I know my '83 1100E will shake a bit under those circumstances but it is never an issue when riding normally.

Joe

[Billy Ricks]

The only time I had any sensation like that is with a tire that sat too long in one position while I did work on the bike. Left the tire flat spotted. Any other problems were all high speed related.

[oldschoolGS]

I would again check the steering head for proper torque and make sure the forks are placed right in the triple clamps in regard to height. By raising the forks in the triple clamps you will quicken steering but also loose some stability, two things you probably do not want on a bike with a 16in front tire. Good Luck, Ed.

[cbxchris]

I`m putting on bridgestone battlax 45`s. Its not a bad shake but thats the first bike I`ve rode in years that has did this. Its not a great feeling and it seems I`m not alone with this bike doing this.

[earlfor]

Chris, my 1150 did the same thing badly when I got it. I pulled everything, front to back apart, checking alignment, forks, wear patterns, swing arm play, fork alignment, trees, head bearings, brakes/rotors, wheel bearings etc etc. I had new Metzlers (33 and 55) on it at the time and I checked rims for true and balance on the tires also. Short version............. take your pos-dampers off and check the seals in them. They are not (supposedly) servicable, but if you unscrew the little screw on top of the black cap, you can disassemble them. A hydraulic repair shop should have replacement seals that will fit if you need them. I also experimented with various weights of fork oil. I found that straight automatic transmission fluid gave by far the most uniform and balanced response between the right and left fork legs.
The cause (as far as I can determine) is worn or aged seals in the posi dampers, or the right and left dampers not being set to the same rebound rate will cause a hydraulic imbalance when the forks compress and rebound. You get a head shake as a result. When and how badly will vary with road surface, speed and riding style, so it is difficult to pinpoint.
With the posi damper arrangement on the forks, the forks are also intolerant of different amounts of oil in each tube. I am guessing that as little as a half ounce can be the difference between perfectly funtioning forks and a shaking front end.

You may also have other problems, so I would check everrything, but if you find nothing wrong in the other things I mentioned I checked on mine, I think you will find the problem to be with oil viscosity, oil amount and condition of the posi-dampers. BTW....I do not use any air in my forks.

Earl

I`m putting on bridgestone battlax 45`s. Its not a bad shake but thats the first bike I`ve rode in years that has did this. Its not a great feeling and it seems I`m not alone with this bike doing this.

[cbxchris]

Thanks Earl...sounds like you have been there with the rest of us. I will try the easy way out first with tires and probably check the bearings while the front wheel is off. This must be a chronic problem with these bikes or so many would not so quickly have posted about it with basically the same problem. Wonder if anyone has been dumped by this?? Makes me kinda scared to run her up to redline in third or so then back off...ugh that would be pretty with my fat as* all over the road! 8O

[crag antler]

BTW....I do not use any air in my forks.

Earl

So you don't have any air at all in your forks.
So when I get my Progressive fork springs and new forks seals in, I should be able to run with no air?
Have you run air in the past and found a reason to not run it in your forks or what was your reason??

[Billy Ricks]

You don't run any air with Progressives. You get the preload dialed in with PVC spacers. The instructions will tell you what length top start woth. Then you can fine tune for your weight and riding style.

[crag antler]

You don't run any air with Progressives. You get the preload dialed in with PVC spacers. The instructions will tell you what length top start woth. Then you can fine tune for your weight and riding style.

Thanks Billy 8) 8) 8)

[earlfor]

I can tell you what will happen Chris if the fork tube rebound rates are mismatched. You will run it up through the gears, keeping it light on the front wheel and nothing will happen until you get to top speed and reduce throttle.
That will plant the front wheel harder and harder, the rebound will immediately swerve the bike hard to one side and it will cross a full lane in a split second, and then head in the opposite direction. The swerve is dynamic and will intensify. The third one will put you off the road if you only have two lanes. The solution is get on the binders with everything there is to keep the forks completely compressed and even. The swerve will stop as you get under 100. :-) I didnt enjoy that particular test run. eh eh

Earl

Thanks Earl...sounds like you have been there with the rest of us. I will try the easy way out first with tires and probably check the bearings while the front wheel is off. This must be a chronic problem with these bikes or so many would not so quickly have posted about it with basically the same problem. Wonder if anyone has been dumped by this?? Makes me kinda scared to run her up to redline in third or so then back off...ugh that would be pretty with my fat as* all over the road! 8O