Speed Wobble

GJD

I have just purchased a 1999 CBR 1100 xx and I am delighted with it. The bike had done 19000 miles but is very. It also came with a double bubble screen, rear hugger and two Givi side boxes plus one Givi top box. The only problem I have is that there is a wobble in the steering at around 40 mph. If you took your hands of the bars it would turn into a full on tank slapper. Its not there below 40mph and not there after it and I wonder is it the side or top boxes that are causing this problem?

Apologies - I posted this under the forum dealing with luggage as well as I was not sure where it sat best!

Looking for any advice.

Rgds
GJD
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ConqSoft

Yeah, mine does the same thing if I have my 3 bag Givi set filled. I think once I get an aftermarket rear shock that can actually handle the extra weight, it will be fine. (the stock shock isn't made to handle that).

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GJD

Many thanks for the prompt reply. Its a reliefe to think it may be nothing more serious than that. My problem is that the boxes were empty at the time but it may well be that a new/upgraded rear shock is required to sort this out.

Thanks again

GJD

ConqSoft

Mine actually does it a little when the bags are empty also, but my shock has half as many miles as yours, so that could be the difference.

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n51jr

This may not help but is so very easy to check / adjust, I would do it.

Head Bearings

I would install a set of tapered bearings, Honda Gold wing upper and lower Goldwing bearings are a direct replacement.

MY 2 CENTS

GJD

I will definitly check out the revised shock option!! Thanks again. GJD

ConqSoft

Just make sure you get one that is sprung correctly for your weight + your bags.

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John01XX

Personally, my bet is the front tire !

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GJD

Its a relativly new tyre but i will check it again. Do you think that the wheel could need balancing?

Thanks for you response

G

ConqSoft

I'm pretty sure it wasn't the front tire in my case since I had the same issue on both my XX's. I added the same 3 bag Givi setup to both soon after I purchased them new. I'll know for sure once I get my Ohlins rear.

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Cowboyflyer

For what it's worth.

I had the same problem with my ST after an new tire was installed.
Went from a Avon to a Michellin. That seem to fix my problem. The
Avon was new also.
Also from experience, I had a bad back tire one time that had a little
wobble in it. It was transfering all the energy to the front tire so it was
causing head shake.

bartonmd

Mine did the same thing after I put the bags on, and got worse when a front tire was close to worn out...

Changed to tapered steering head bearings and, even given the same bags on, same load, same tire, and everything, no more wobble... Plus, it doesn't even wobble with my wife on the back, with all 3 GIVI's full, with the stock shock...

Mike

ConqSoft

Tapered bearings should allow more free movement than non-tapered, so I'm not seeing how those could make a difference... The bars should wobble even more in that case.

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bartonmd

This is the same thing several people have done, with the same results... Their results are actually why I did it...

I think the issue is; the standard ball bearings start to wear a detent in the mating surfaces pretty quickly, with the VERY small contact area they have, and I do believe the oscillation is just the ball bearing bouncing from one side of the detent to the other...

Yes, it does steer much easier, and has a TON more road feel!

Mike

flitemdic

My guess, too. I have no Givi's and had the same vibration at 42-47 mph. Changed the tire, no more vibration.

Head bearings number two, and the shock thing is probably true, too, but $150 for a new front tire beats the $750 for a decent new shock

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N2YN 8/22/2004

bartonmd

Yes, the front tire being worn is the cause, only because the stock steering head bearings make it sensitive to what kind of shape your tire is in... With the tapered SHB's, it's not NEARLY as sensitive to what kind of shape the tires are in, so if you spend the $42 on bearings (which the stock ones are probably already getting worn anyway), you can save the $60 on the remaining tread on this tire... then the $60 on the next one, and the next one... you get the point...

Mike

ConqSoft

I guess you guys missed where I said that it did it on two of my XX's, that were brand new, with new tires, with the Givi bags added? I'm not saying a bad front tire won't cause this same thing, but I'm saying that it's not the only thing.

The added weight on the rear causes the front end to be light, causing the bars to dance if you release them.

Raising the rear with a shim or getting an aftermarket shock to correct this will solve the issue.

Same symptoms, and solution, mentioned by cbr99xx here: http://www.cbrxx.com/honda-cbr-xx-te...br-1100xx.html

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bartonmd

mine did it 1-up after I did the 6mm shim, with the correct rider sag....

It, now, doesn't do it 2-up, with my 210lb, 6' tall wife, with full GIVI's, and the preload set for me alone... It also doesn't do it with the preload set for2-up, with the same load... The only thing I changed when I did the bearings was the bearings, and it stopped instantly... same tires, same ride height, everything...

It didn't do it with new tires, but would always do it with a worn front tire.

Mike

rdkng88

my wife is a little heavier than the bags and my 98 bird handles great with her on the back. go for the tire check the balance.
rdkng88

ConqSoft

I'm sure the weight of the rider has something to do with it also. I'm only 160lbs, so I'm not helping to hold down the front end very much.

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n51jr

I do not want to dispute any one here but I have seen this slow speed wobble to be quite common with the GL1500 Gold Wings.
The fix is nearly always the preload on the steering stem bearings and most often than not the bearings will require replacement.
The tire and or suspension problems will exaggerate this problem but the bearing preload seems to be the number 1 fix.

I will say that if you can get a slapper at 40 you will undoubtably be at risk at high speeds.

The only reason I bring this up is that a new shock and or tire may mask a problem that can resurface at a much higher speed.

The advantage of the tapered over roller bearings is the amount of preload you can achieve without binding.

I guess I gave 4 cents this time

shovelstrokeed

I have had this come and go on various bikes over the years. New front tire usually fixes it. Every once in a while, new steering head bearings are necessary. Your tire spends all its life nibbling at the road surface and placing a series of small forces into the steering as a result. Those small forces are normally damped by your hands an arms in the course of riding the bike. In fact, when this phenomenon occurs, if you put so much as one hand back on the bars, it stops right away.

This, BTW, is not a "speed wobble". By definition, that occurs at high speed and is the result of much stronger forces in the chassis. Usually a mis-aligned rear tire or twisted steering head causing the gyroscopic precession of the wheels trying to get square with the earth to feed enourmous forces into the frame. If your steering is crabbed while trying to run in a straight line, you'll find out what a real speed wobble feels like. Not a bit of fun and won't go away with just gently putting a hand on the bar.

Ditto "Tank Slapper" and head shake. These are usually caused by a front tire that loses traction either due to being lightened under acceleration out of a turn and then encountering bumps which knock it off axis or by a momentary loss of traction on the front followed by a recovery. The bars want to kick to the side and, at certain speeds, the kick and recovery will excite a natural resonance in the chassis/suspension and Hoo Boy! the fun begins. The forces are really extreme. Bars are literally ripped from your hands as the oscillation goes from bad to worse and backing off the throttle and loading the front tire even more exacerbates the situation.

I have experienced both. The speed wobble usually starts with what feels like a slow side to side weave of the bike, seemingly originating at the rear tire. As it starts to increase in amplitude some effect will be felt at the bars. This too is a harmonic effect and can sometimes be ridden through. A steering damper can sometimes do more harm than good in this situation as it can serve to amplify the forces going into the frame.

Tank slappers and head shake tend to happen much more quickly. I suppose that order should be reversed as it is usually head shake that leads into the tank slapper. A steering damper can often help with these.

One last point, over torque on the steering head bearings is a bad idea. There are specifications for proper preload that will allow the bearing to turn freely without damage. Exceed those specifications and you risk damage to the bearings which can bring back the problem. Of course, the simple thing is just don't let go of the friggin' bars!!!

flitemdic

This last post is going to give me a chance to display my ignorance, or at least display how incredibly lucky I've been over the years. Having owned many bikes over the years, I've never had the misfortune to have a true "tank-slapper". It was mentioned that letting up on the throttle and "reloading" the front tire makes things worse. So what's the answer in the 0.5 seconds you have to react?

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N2YN 8/22/2004

bartonmd

Yep, 180 here, with heli-bars...

Mike

OZDave

It's usually over before you can react, or One way or the other it's time. If you have time don't roll off the throttle.

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