Vibrating handlebars due to flex


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Vibrating handlebars due to flex

Postby WingAdmin » Fri Oct 12, 2012 10:52 am



Just a quick question for GL1500 owners. This is something my 1500 has done for as long as I've had it: When at highway speeds, and I hit a bump, the handlebars vibrate, maybe for half a second. I've put my hand on the triple tree while keeping the other hand on the end of the handlebar, and it's definitely the actual handlebar flex that causes the vibration - there's no vibration on the triple tree, only at the end of the handlebars. It's visible - and likely because the handlebars are quite long and wide, with clutch, brake, switchgear, etc. all hanging on the end of them. It's like taking a long bar and whacking the end of it - it will vibrate back and forth.

It's always annoyed me, but I figured it was just the price of having large handlebars. But as I rode yesterday (8 hour ride, so lots of time to think), I started thinking of ways to "fix" it, by stiffening the handlebars. First however, I thought I'd ask to make sure it's normal behavior for 1500's. If not, then I'll start looking for a problem. If it is, then I'll start thinking of a fix. One idea I had was to fill the handlebars with concrete or epoxy, making them extremely stiff, and eliminating all flex.

Thoughts?



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Re: Vibrating handlebars due to flex

Postby Sempai » Fri Oct 12, 2012 12:18 pm

This doesn't sound normal to me. I've logged in two cross-country trips on my 1500, plus a good 500 miles a week right here at home cuz I don't own a car and ride the GWing all year long. The head wobble you're describing used to happen to me on my '94 SE model, but I installed a Superbrace and I've never wobbled since. Before you go filling your bar with cement, you may consider trying some motorcycle bar end weights. They are commonly used in the sport bike genre, perhaps they may do the trick for you. Adding weight to the OUTERMOST reaches of the handlebars will increase the head's rotational (lateral) inertia, decreasing its aptness to wobble.

http://www.racingplanetusa.com/handleba ... PAodLWAATw
Keep the rubber side down.

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Re: Vibrating handlebars due to flex

Postby WingAdmin » Fri Oct 12, 2012 12:30 pm

Sempai wrote:This doesn't sound normal to me. I've logged in two cross-country trips on my 1500, plus a good 500 miles a week right here at home cuz I don't own a car and ride the GWing all year long. The head wobble you're describing used to happen to me on my '94 SE model, but I installed a Superbrace and I've never wobbled since. Before you go filling your bar with cement, you may consider trying some motorcycle bar end weights. They are commonly used in the sport bike genre, perhaps they may do the trick for you. Adding weight to the OUTERMOST reaches of the handlebars will increase the head's rotational (lateral) inertia, decreasing its aptness to wobble.

http://www.racingplanetusa.com/handleba ... PAodLWAATw


I've already got a Superbrace, AND bar end weights (although it also did it before I had the end weights). It's not wobble that I'm talking about - the wheel, forks, triple tree, etc. are rock solid while only the ends of the handlebars vibrate. It's a very rapid vibration that lasts at most half a second, when I go over a large bump in the road. Adding more weight to the ends of the handlebars would actually INCREASE the vibration, as it would cause the handlebars to flex even more.

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Re: Vibrating handlebars due to flex

Postby Sempai » Fri Oct 12, 2012 2:29 pm

hmmm...
This sounds awful strange. I wonder, from your latest comment, if your bars, themselves, are loose in their clamps. I'd think that if they were TIGHT, then the whole front end would wobble, not JUST the bars? I'm quite curious to learn more about this particular issue you're having.
Adding weight to the entirety of the bars seams like a waste. The weights I referred to should be sufficient IF that is your problem. The added inertial mass of the weights at the ENDS of the bars keeps them steady. According to Newton's 1st law of motion: "Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it." This being so, the extra weight at the bar ends would resist entering a wobble. Well, that's the theory anyway.
Keep the rubber side down.

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Re: Vibrating handlebars due to flex

Postby vtxcandyred » Fri Oct 12, 2012 2:35 pm

I have a 93SE and never had that happen to me. I did have a wobble common with bad or worn tires which went away with new rubber. I do have Kury Iso grips with the end weights and a form of a super brace. But like I said, I did not have this before. Perhaps you have "fixed it" too much. I know you have put a LOT of new stuff on it and maybe its in that somewhere. Fork bearings or wheel bearings. I have heard that you can fill the handle bars with rubber tubing like tygon and fill it with bearing type balls and seal the ends up and this will take some vibration out of the bars. Don't really KNOW what it could be. Sorry I'm not more help.

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Re: Vibrating handlebars due to flex

Postby WingAdmin » Fri Oct 12, 2012 3:30 pm

Sempai wrote:hmmm...
This sounds awful strange. I wonder, from your latest comment, if your bars, themselves, are loose in their clamps. I'd think that if they were TIGHT, then the whole front end would wobble, not JUST the bars? I'm quite curious to learn more about this particular issue you're having.
Adding weight to the entirety of the bars seams like a waste. The weights I referred to should be sufficient IF that is your problem. The added inertial mass of the weights at the ENDS of the bars keeps them steady. According to Newton's 1st law of motion: "Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it." This being so, the extra weight at the bar ends would resist entering a wobble. Well, that's the theory anyway.


They're not loose in the clamps, as I've had them off to torque the steering head bearings, and torqued them to spec when I put them back on. That said, they did it before and after that.

It's not so much about adding weight to the whole bar, it's about stiffening the whole bar to prevent flex in the first place.

Adding weight to the end of the bar reduces the resonant frequency - but it increases the propensity for the bars to flex. Think about a long bar, fastened at one end. Now displace the fastened end of the bar up and down quickly. The loose end of the bar might move up and down briefly. Now put a big weight on the end of that bar and try again. The weighted end has more mass, more inertia, so once it is displaced, it will tend to move up and down for a longer time.

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Re: Vibrating handlebars due to flex

Postby WingAdmin » Fri Oct 12, 2012 3:33 pm

vtxcandyred wrote:I have a 93SE and never had that happen to me. I did have a wobble common with bad or worn tires which went away with new rubber. I do have Kury Iso grips with the end weights and a form of a super brace. But like I said, I did not have this before. Perhaps you have "fixed it" too much. I know you have put a LOT of new stuff on it and maybe its in that somewhere. Fork bearings or wheel bearings. I have heard that you can fill the handle bars with rubber tubing like tygon and fill it with bearing type balls and seal the ends up and this will take some vibration out of the bars. Don't really KNOW what it could be. Sorry I'm not more help.


I have the Kury iso grips, also with the end weights (although it did this before I had those weights put on), and a super brace. I've torqued the steering head bearings, and just replaced the wheel bearings. That said...the bike has done this for as long as I have owned it, long before I added anything to it. I haven't added much to the handlebars - and what I did add, doesn't weigh very much.

Perhaps the next step is to pull the handlebar covers off and apply a load to the handlebars to find out exactly where the flex is occurring.

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Re: Vibrating handlebars due to flex

Postby vtxcandyred » Fri Oct 12, 2012 6:28 pm

WingAdmin wrote:
vtxcandyred wrote:I have a 93SE and never had that happen to me. I did have a wobble common with bad or worn tires which went away with new rubber. I do have Kury Iso grips with the end weights and a form of a super brace. But like I said, I did not have this before. Perhaps you have "fixed it" too much. I know you have put a LOT of new stuff on it and maybe its in that somewhere. Fork bearings or wheel bearings. I have heard that you can fill the handle bars with rubber tubing like tygon and fill it with bearing type balls and seal the ends up and this will take some vibration out of the bars. Don't really KNOW what it could be. Sorry I'm not more help.


I have the Kury iso grips, also with the end weights (although it did this before I had those weights put on), and a super brace. I've torqued the steering head bearings, and just replaced the wheel bearings. That said...the bike has done this for as long as I have owned it, long before I added anything to it. I haven't added much to the handlebars - and what I did add, doesn't weigh very much.

Perhaps the next step is to pull the handlebar covers off and apply a load to the handlebars to find out exactly where the flex is occurring.

Did'nt you replace the steering head bearings and the front axle bearings?????

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Re: Vibrating handlebars due to flex

Postby RoadRogue » Fri Oct 12, 2012 10:43 pm

I went for a ride tonight to see if mine did this too.I road over train tracks several times and hit every pothole I could find at every speed.I could feel the bumps and the suspension working through the ends of the grips but not what I would call flexing beyond what I would expect or have experienced on any other bike. I know Im no help at all. Let us know what you find/come up with. 8-)
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Re: Vibrating handlebars due to flex

Postby robb » Sat Oct 13, 2012 11:31 am

I have a slight twitch depending on how bad a road is, but was warned about the Tulsa shield possibly generating the problem. Now that front tire is cupping can feel lots of stuff but never enough to feel need for both hands to control. With shield removed it is smooth as silk. At times you can physically see the shield twist, as with a stiff wind or being passed by a Transfer truck. Even Honda shop said wheel and tree bearings were OK. It is practically eleminated riding solo with 10psi in rear shock, guess it is the angle of shield. I'm using show chrome heated grips without weight.

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Re: Vibrating handlebars due to flex

Postby WingAdmin » Sun Oct 14, 2012 10:06 am

vtxcandyred wrote:Did'nt you replace the steering head bearings and the front axle bearings?????


The steering head bearings had only a few thousand miles since replacement, so I just torqued them to spec. I replaced the front axle bearings last week.

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Re: Vibrating handlebars due to flex

Postby WingAdmin » Sun Oct 14, 2012 10:10 am

I had a closer look at the handlebars with the cover off the other night, and the flex is definitely torsional (rotational) flex occurring right around the first bend after the bars exit the steering head. I had dinner with Gary and Betty from Cyclemax on Friday, Gary said he had never seen a 1500 do the vibration I'm talking about. He seemed to think it might be from the bars being adjusted too far back, so I'm going to check that and see if that's the case - I do know I adjusted them back a bit from the factory position, both because my arms are a bit short, and to give me extra steering lock before the bars hit the Tulsa windshield.

If that's the case, the next step is to figure out how to stiffen them. Filling them with concrete would be nice, but concrete is corrosive and would rust them out. I thought perhaps filling them with epoxy might do the trick though.

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Re: Vibrating handlebars due to flex

Postby robb » Mon Oct 15, 2012 8:06 am

Fill with sand and seal end with silicon. :

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Re: Vibrating handlebars due to flex

Postby virgilmobile » Mon Oct 15, 2012 9:54 am

Granted,I'm no mechanical structural engineer,but as I recall a solid rod will flex more than a hollow rod.Something about the shearing force being distributed around the "pipe" verses through the "rod".

I know that I can bend a solid rod easier than a pipe.
I think your problem was resolved in the old dirt bikes with a cross brace.
A bar you could hang a air freshener on :D
I've never heard of a handle bar being a solid core,or modifying one in that manner.
If your "flex" is at the first bend,I don't believe anything other than a external reinforcement will help.
The movement at the bend is so small and extreme shear torque that epoxy or almost any filler will simply compress,bend or break.

I'm not trying to pu-pu any idea,just the facts as I remember them.
I hope I'm wrong and pouring sand into the handlebars will fix it.

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Re: Vibrating handlebars due to flex

Postby WingAdmin » Mon Oct 15, 2012 12:00 pm

virgilmobile wrote:Granted,I'm no mechanical structural engineer,but as I recall a solid rod will flex more than a hollow rod.Something about the shearing force being distributed around the "pipe" verses through the "rod".

I know that I can bend a solid rod easier than a pipe.
I think your problem was resolved in the old dirt bikes with a cross brace.
A bar you could hang a air freshener on :D
I've never heard of a handle bar being a solid core,or modifying one in that manner.
If your "flex" is at the first bend,I don't believe anything other than a external reinforcement will help.
The movement at the bend is so small and extreme shear torque that epoxy or almost any filler will simply compress,bend or break.

I'm not trying to pu-pu any idea,just the facts as I remember them.
I hope I'm wrong and pouring sand into the handlebars will fix it.


I doubt pouring sand would fix it - if anything, it would ADD mass to the handlebars, and make the problem WORSE.

Incidentally, a solid bar with the same diameter, of the same material, is stronger, and will flex less than a hollow bar. However, a hollow bar of the same WEIGHT as a solid bar made of the same material, will be much stronger, as it will be much larger in diameter.

I suspect you're right about the filler compressing or breaking. The amount of movement, and the torque being applied, would just make it fail rapidly.

I think I'm down to:

a) rotating bars to original position to see if it makes a difference
b) if not, replacing the bars

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Re: Vibrating handlebars due to flex

Postby virgilmobile » Mon Oct 15, 2012 12:15 pm

Your right about the bar diameter.
I remember the gate for the elephant at the zoo was being bent just by the mass of the elephant pushing on it,the gate was replaced with a tubular design.The elephant couldn't bend it.
I think the original gate was 2'' solid rods and the replacement was 4" pipe.

Because mine and many others don't have the problem that you have,I wonder what is the cause.
Mounting angle,added weight,your magnetic personality,weakness in the steel,low bid metal.....Hmmmm.
Keep us up to date.

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Re: Vibrating handlebars due to flex

Postby robb » Mon Oct 15, 2012 7:59 pm

I used to race gocarts at speeds up to 130mph and sand was used in frame to control vibration. Don't have to completely fill, but sand can counteract vibration.

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Re: Vibrating handlebars due to flex

Postby WingAdmin » Tue Oct 16, 2012 10:58 am

robb wrote:I used to race gocarts at speeds up to 130mph and sand was used in frame to control vibration. Don't have to completely fill, but sand can counteract vibration.


I'm on the fence about this. I was also looking at a product called Barsnake which is a heavy, soft compound that is pushed into the handlebars to add mass. Adding mass will significantly lower the resonant frequency, perhaps to the point where the resonant frequency is lower than the flexing bar will support. On the other hand, adding mass will also increase the inertia of the whole system, increasing the bar flex, which is what is creating the vibrations in the first place.

I think I'll have to do a test: find something reasonably heavy - 2-3 pounds or so - and clamp it near the ends of the handlebars, then see what difference it makes (if any). The ideal solution would be to REDUCE weight, which would reduce the inertia, and the stiffness of the existing bars would be sufficient to prevent the vibrations from occurring.

Hmm. I wonder if just hanging on tight, and leaning forward to put my weight on the bars would suffice as a test?

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Re: Vibrating handlebars due to flex

Postby robb » Tue Oct 16, 2012 12:44 pm

Ponder this, just the addition of my 34oz butler cup on the left side will change the dynamics of road feel.

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Re: Vibrating handlebars due to flex

Postby vtxcandyred » Tue Oct 16, 2012 3:35 pm

WingAdmin wrote:
robb wrote:I used to race gocarts at speeds up to 130mph and sand was used in frame to control vibration. Don't have to completely fill, but sand can counteract vibration.


I'm on the fence about this. I was also looking at a product called Barsnake which is a heavy, soft compound that is pushed into the handlebars to add mass. Adding mass will significantly lower the resonant frequency, perhaps to the point where the resonant frequency is lower than the flexing bar will support. On the other hand, adding mass will also increase the inertia of the whole system, increasing the bar flex, which is what is creating the vibrations in the first place.

I think I'll have to do a test: find something reasonably heavy - 2-3 pounds or so - and clamp it near the ends of the handlebars, then see what difference it makes (if any). The ideal solution would be to REDUCE weight, which would reduce the inertia, and the stiffness of the existing bars would be sufficient to prevent the vibrations from occurring.

Hmm. I wonder if just hanging on tight, and leaning forward to put my weight on the bars would suffice as a test?

I believe if you have a resonant frequency associated with this then I would be looking into it further. I have seen metal fatigue and crack from resonance. And a hollow tube would be more prone to this. I'm certainly no engineer but I do work with a whole plant full and see some pretty intriguing things. Two pennies.

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Re: Vibrating handlebars due to flex

Postby bustedwing » Tue Oct 16, 2012 7:39 pm

I also have my bars adjusted as you do and just so you know I have not had that happen on any Gold Wing, either 12 or 1500. As a matter of fact I was a little baffled trying to understand your problem, but can say I have ran into that on older dirt bikes but they were well worn so it was no wonder. The only thing I can think of is maybe a defective handlebar set. Can you try another set in its place?
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Re: Vibrating handlebars due to flex

Postby vtxcandyred » Tue Oct 16, 2012 7:43 pm

I know it will change the look of the bike but I have seen bars with a bar between the upper portion. ????

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Re: Vibrating handlebars due to flex

Postby WingAdmin » Tue Oct 16, 2012 9:05 pm

I spent a good part of my ride home from work today on I-480, hunched over with one hand on top of the triple tree, other hand on the throttle, aiming for every bump I could see. :)

My conclusion: The handlebars are not flexing. The entire triple tree is moving. When I hit a bump, the triple tree is rotating backward, which flips the ends of the handlebars up quickly, inducing the wobble. Only thing I can think of that would cause that is loose steering head bearings.

I stopped at Cyclemax on my way home to pick up something I had ordered. Gary agreed with my analysis.

I got home and lifted up the bike. Sure enough, the front end is loose AGAIN. Dammit! I've re-torqued those bearings twice now!

The PO had told me that the steering head bearings had just been replaced when I bought the bike. I've had nothing but problems with them ever since I got it. I've had enough - when I tear the front end apart this winter, I'm going to replace the steering head bearings, and be done with this once and for all.

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Re: Vibrating handlebars due to flex

Postby vtxcandyred » Tue Oct 16, 2012 9:14 pm

I have always adjusted my bars by feel. To "ME" with the front wheel raised I should be able to push one way or the other and it should move to the stop without any binding or stoppage and do it smoothly. I adjust it so it JUST does this. It may take me a while but I can get it to this point. It worked on my old in line fours and my 02 VTX. I know with all the stuff on a wing it will be hard to do but it can be done even if you only do it by a judgment call. Again, two pennies.

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Re: Vibrating handlebars due to flex

Postby virgilmobile » Tue Oct 16, 2012 9:28 pm

It sure seems like your having to do a lot of work on that bike,just one more thing, right?
At least you identified the problem,annoying as it may be.
Good diagonistic job again.




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