K
kurt12345
Guest
when i accletrate hard with my gs1100 sometimes the steering wobbles and the bike wobbles, and also does it at high speed and idea??
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G
Guest
Guest
Your front tire might be worn or out of balance. Could even be a bent rim or even bad wheel bearings.
In my experience it's usually the tire.
In my experience it's usually the tire.
R
rosco15
Guest
The rear tire could be in the swingarm crooked.
G
Guest
Guest
Could it be weak rear shocks? You need to nail down the problem. High speed wobbles are dangerous. I know from experience.
If you can, try increasing your rear shock spring pre-load to see if that helps.
If you can, try increasing your rear shock spring pre-load to see if that helps.
Good luck on finding the cause. I know I'm the only one who has seen this problem, but on several GS's I've seen when they get older, this happens. I've tried everything I could think of to fix this problem. I've changed steering bearings, wheel bearings, tires, wheels, swing arm bearings, swingarms, shocks, fork springs, anything I could think of that may cause it .
Check the main nut on the steering head...I had a similar problem when first getting mine going, only to find out the the nut was for the most part, finger tight. Torque it down to spec and then put the bike on the center stand and grab the forks and pull back and forth inline with the bike to check the bearings. If it's tight, move onto the rims and look for run out side to side. If all checks out front and back, defer to Chef's post.
Good luck.
Good luck.
Kurt, Just slow down !! :-D Which 1100 is it ? Mine is a 82 EZ with that issue. Im working it from all the angles mentioned. Tires first - no diff. Swingarm bearings - no diff. Lazer alignment - no diff. Checked every bolt and nut for tightness - no diff. Steering bearing nut - noticable diff. When it warms up Ive got new progressive front & back, new All balz steering bearings, and newfork seals in a box. Then we will see. Stay tuned....as riding season approaches this topic will pop up all the time.
Not like the good old daze when a 5 mile stretch of straight road was not enough. Use to twist the throttle to the stop and then some. HANG ON. \\
/
Re-torque the steering head bearings. When on the centerstand, sitting on the back of the seat (or get an assistant) to get the front tire off the ground, there should be just a little drag as you move the bars side to side.
F
foghog
Guest
But be careful not to get the head bearings too tight since that can be a problem too.
M
Mike McNaney
Guest
I had the same problem as most of us do it looks like. Mine went away after I did all of the following. im not sure which one item was the culprit as I did them all at once but I think lite front weight was the biggest factor.
Mine started it 100 times worse when I changed the rear tire to 140/80 which lowered the rear end a full inch. In a stock configuration, I think the front end gets lite if the rear shocks are sagging.
Steering head nut adjusted as spec, loosened the fork brace above the front fender and tightened it down last after making sure the forks were both straight on the front wheel axle. removed the air system and covered the holes in the forks. lowered the front end to put more weight on the front. used 15w40 in the front forks in exactly the same amounts, and keep the damping adjustment at 3 or 4 only. Changed front tire to 110/19 size.
You can lower the front two ways.
Loosen the clamps and slide the tubes up. (exacty equal amounts!)
or by adding another rebound spring inside each tube under the plunger so there are two on each side, which is the "official way"
If you slide the tubes up, they will only go about 3/4" because they hit the handlebars. I use a set of barbacks which raises and moves the bars back an inch so I can get my tubes up as much as I need. Makes for a great sitting position also.You've got to make sure the fender doesnt hit the oil cooler or front brake union though on a big bump. You cant just drop it to the floor like that. I found that a inch and a quarter is about the max.
After all this stuff I dont get wobble anymore up to 140.
This is on a 83' E model. After writing all this I notice you dont mention what model and since they all have quite different weight distribution, it may or may not have anything to do with yours.
Mine started it 100 times worse when I changed the rear tire to 140/80 which lowered the rear end a full inch. In a stock configuration, I think the front end gets lite if the rear shocks are sagging.
Steering head nut adjusted as spec, loosened the fork brace above the front fender and tightened it down last after making sure the forks were both straight on the front wheel axle. removed the air system and covered the holes in the forks. lowered the front end to put more weight on the front. used 15w40 in the front forks in exactly the same amounts, and keep the damping adjustment at 3 or 4 only. Changed front tire to 110/19 size.
You can lower the front two ways.
Loosen the clamps and slide the tubes up. (exacty equal amounts!)
or by adding another rebound spring inside each tube under the plunger so there are two on each side, which is the "official way"
If you slide the tubes up, they will only go about 3/4" because they hit the handlebars. I use a set of barbacks which raises and moves the bars back an inch so I can get my tubes up as much as I need. Makes for a great sitting position also.You've got to make sure the fender doesnt hit the oil cooler or front brake union though on a big bump. You cant just drop it to the floor like that. I found that a inch and a quarter is about the max.
After all this stuff I dont get wobble anymore up to 140.
This is on a 83' E model. After writing all this I notice you dont mention what model and since they all have quite different weight distribution, it may or may not have anything to do with yours.
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G
Guest
Guest
When you accelerate hard at speed???
Means you should be leaning further foreward, you're picking up the front wheel!!!
Means you should be leaning further foreward, you're picking up the front wheel!!!
I agree, the bearings should have a minimal amount of drag. I tighten the bearings enough to stop the wobble on mine, But I knew they should not need to be as tight as I had to tighten mine to stop it, so I loosened them back to "slightly tight normal". The wobble was still there.
K
kurt12345
Guest
yeah the main nut thats hold the steering head together was finger tight so i tuned them all up and it hasnt wobbled since :-D , thanks for the info
B
Boondocks
Guest
There are two main types of moving instability, wobble (low speed) and weave (high speed). Wobble is a front end condition, causes described at Frontend Shaking.
A high speed weave is a rear end condition, and is more dangerous. See Steering Damper. It is important to recognize that all motorcycles have these two types of rolling instabilities caused by resonant frequencies. A well designed and maintained bike will damp these resonant peaks and keep them under control so that they are not noticeable.
Of course, loose parts, bearings, bald tires, etc. contribute to underdamping, and will exacerbate rather than control resonant vibration. Experimentation is the key to finding a solution to a high speed weave. Lightweight riders find that it is more of a problem, because body mass is itself a damping factor. A lightweight rider who experiences a high speed weave may find that it disappears when carrying a passenger.
Sometimes transferring the rider's weight forward over the tank will help control a high speed weave. Some bikes may work better or worse with certain tires to dampen resonant frequencies. Tires are suspension components and vibration dampers. Changing air pressure can affect a tire's effectiveness in eliminating instabilities.
If rear shocks have adjustable damping, overdamping of the shocks may cause a weave. Reducing the shock damping force may eliminate the weave. The resonant energy that was formerly transferred into the rear wheel weave with stiff shock damping is transferred into heat when the damping in the shock is reduced. This allows the action of the shock to attenuate the magnitude of the resonant frequency.
Suspension is a compromise, and there is no best setting for all conditions.
A high speed weave is a rear end condition, and is more dangerous. See Steering Damper. It is important to recognize that all motorcycles have these two types of rolling instabilities caused by resonant frequencies. A well designed and maintained bike will damp these resonant peaks and keep them under control so that they are not noticeable.
Of course, loose parts, bearings, bald tires, etc. contribute to underdamping, and will exacerbate rather than control resonant vibration. Experimentation is the key to finding a solution to a high speed weave. Lightweight riders find that it is more of a problem, because body mass is itself a damping factor. A lightweight rider who experiences a high speed weave may find that it disappears when carrying a passenger.
Sometimes transferring the rider's weight forward over the tank will help control a high speed weave. Some bikes may work better or worse with certain tires to dampen resonant frequencies. Tires are suspension components and vibration dampers. Changing air pressure can affect a tire's effectiveness in eliminating instabilities.
If rear shocks have adjustable damping, overdamping of the shocks may cause a weave. Reducing the shock damping force may eliminate the weave. The resonant energy that was formerly transferred into the rear wheel weave with stiff shock damping is transferred into heat when the damping in the shock is reduced. This allows the action of the shock to attenuate the magnitude of the resonant frequency.
Suspension is a compromise, and there is no best setting for all conditions.
When the handlebars on my "80" GS 1100 "E" started slaping both sides of the tank, at appx. 115mph. Was that a (low speed) wobble or a (high speed) weave. Never figured out which it was, cause there wasn't enough left of the bike to try to find what caused the problem. Believe me, it was a very very serious condition.
Ahhh.......Not to be a smart ass or any thing but are you posting this from heaven ?
B
Boondocks
Guest
That's the classic "tank slapper". It's the most dangerous and worst instability of all, but it's usually treated as a special case when motorcycle instability is discussed. It's like a low speed wobble in its behavior, except it can be uncontrollably violent at higher speeds. It isn't common on bikes like yours, which are more prone to a high speed weave (rear wheel steering). It's more likely to found on a high powered motorcycle like a racing bike which doesn't have adequate steering damping. Sometimes on bikes prone to this behavior, a certain type of road surface can induce an uncontrollable high amplitude steering wobble. There are no tell-tale signs that a road surface might cause this, it is an individual interaction between the motorcycle, its tires and the road.
One of the most common occurences of a tank slapper would be a race bike hitting a sizeable bump or lofting the front tire when accelerating out of a turn. If the front tire doesn't land perfectly true to the direction of travel, the self-centering action of the front end will whip it to the other side. The bump or off center landing can create the tank slapper oscillation. The very steep steering geometry of race bikes contribute to this tendency. That's why they typically have steering dampers, and some have reduced the steering lock to a small arc to prevent head shake from gaining momentum. It would be hard to turn one of these bikes around due to the lack of front wheel turning arc, but it is not missed in high speed racing and contributes to stability.
See the section on Headshaking, tankslapping and steering dampers for a good explanation.
Well Boondocks, again you are right. The bike I wrecked had been having a slight wooble at high speed. but nothing serious, it did get your attention, but nothing I couldn't handle. The day of the wreck, I was drag racing a GS 1150, & was in front of him. The front end was light, as I was accelerating, & I did hit a rough place in the pavement.Since then, I've had a few other GS's that had that same wobble (weave) that I never got straightened out, but now it no longer matters, I'm not planning on going that fast anymore.
B
Boondocks
Guest
I think that a lot of high speed weave problems are not solved because a rider may not realize that it is a rear end oscillation and focuses his attention on the front end. It's usually sort of counterintuitive to think of the rear wheel having steering input without tire slippage. A rear tire with excessive lateral runout (had one of those) can cause the weave, as can loose swingarm bearings, wrong/worn tire, and improperly adjusted shocks among other things.
My next set of tires is H rated, not V, so I don't plan on going over 130 mph.:-D