High speed wobble

[Lotsokids]

Today was the most violent wobble EVER. Coming home from work (on the most bumpy road) a car challenged me to race. Well...... like most of you would do, I accepted the challenge and showed him who was boss. But under acceleration on the bumpy road, I knowingly (and stupidly) invoked the wobble. It was really bad. I felt the bike nearly catch air between bounces as I held on the best I could. It was VERY violent. Stupid me... I knew it was coming.

I'll check the head adjustment again. A few months ago, I accomplished the "bounce test" but acquired the low-speed weave (too tight). I loosened just a hair... then got the wobble again. Seems to be no happy middle. Maybe the race is grooved.

At ANY speed, I can induce the wobble by jerking the bars a little.

I've got to do something. During the wobble, it feels like the whole frame is flexing.

**EDIT**

I just checked air pressure in my front tire, and it was at about 22 PSI. Now pressurized to 45 - front and rear (rear was 35). Maybe that's a factor. I've filled the front tire once before. Seems I have a very slow leak. Maybe that contributes to the wobble?

**EDIT #2**

Just took it out for a ride. Much more stable. An Audi decided to race me. I pushed it very fast - to nearly 120 MPH and got a slight wobble - but controllable.

I think that maybe the bike is just designed unstable. Any flick of the handlebars develops into a resonant wobble at any speed. MAYBE I flick the bars a little during shifting.

Best idea is that I should keep the tire pressure up and tone down my aggressive riding style.

 

[adambweird]

Nah, theres ways to make it better, keep riding aggressive! Id get some solid motor mounts and a braced swingarm, thatll help things quite a bit and its cheaper than switching to radials.

 

[DMAN999]

I've had my stock 2000 since 2001 and I check the steering head adjustment every Spring.
I have Never had a wobble except once when my front tire got cupped.
And I have had my Vmax up to 140-145 mph more times than I can count in the 14 years I've been riding it.
I keep my tires at 33 psi front and 36 psi rear as recommended in the Owners Manual.

So No it is Not a design flaw.
I'd check all your bearing (wheel, steering head, swing arm, etc) just to be sure they are all in good shape.

I did add Progressive fork springs a few years ago and recently added weld on frame braces both of which helped a lot with cornering stability.
And a Shinko TM 230 rear with a Bridgestone Battlax BT-45V also help a LOT for riding hard on twsty roads.

 

[Fire-medic]

My Gawd, lower your tire pressures!

You want more-sure handling, get radials, nothing will enhance your riding experience like radials will. Steer better, turn better, brake more-surely, hookup better, but don't run 45 PSI! All that will do is wear-out the center of your tires more-quickly.

 

[Lotsokids]

...]don't [/COLOR][/U][/I][/B]run 45 PSI! All that will do is wear-out the center of your tires more-quickly.

My tires are embossed with 42 PSI.

 

[DMAN999]

My tires are embossed with 42 PSI.

42 PSI is the Maximum cold pressure for that tire as stated by the Manufacturer, it is NOT the recommended air pressure.
Tire manufacturers ALL state to use the recommended pressure listed in your exact motorcycle Owners Manual.
And for a 1985-2007 Vmax that is 33 psi front and 36 psi rear for high speed riding.

 

[Specs95t]

This issue comes up quite a bit. One other thing to check is the amount of stress on the front forks. Whether doing a FF or swappimg springs, or doimg the Moreley bounce test, on thing is common: you need to loosen the pinch bolts on the top triple tree to allow for the suspension tubes to setlle in stress free.

My point is to start with the basics. get the bike up on the center stand, load the back end to have the front end hang, loosen the pinchbolts on both triple trees and retighten to spec. This will establish a stress free fork conditon and allow that to no longer be a factor.

I say this because if the forks are pre-stressed because of slightly mis-aligned pinch bolt forces - and you hit a bump, the prestress can add to the forks reaction and "reasonate"...

Just a thought....

Sent from my GT-P7510 using Tapatalk

 

[one2dmax]

I usually run 38-40 in my tires (though they are usually radials when i have the opportunity). Similar pressure usually for the stock bias tires too.

 

[brad bruggeman]

Today was the most violent wobble EVER. Coming home from work (on the most bumpy road) a car challenged me to race. Well...... like most of you would do, I accepted the challenge and showed him who was boss. But under acceleration on the bumpy road, I knowingly (and stupidly) invoked the wobble. It was really bad. I felt the bike nearly catch air between bounces as I held on the best I could. It was VERY violent. Stupid me... I knew it was coming.

I'll check the head adjustment again. A few months ago, I accomplished the "bounce test" but acquired the low-speed weave (too tight). I loosened just a hair... then got the wobble again. Seems to be no happy middle. Maybe the race is grooved.

At ANY speed, I can induce the wobble by jerking the bars a little.

I've got to do something. During the wobble, it feels like the whole frame is flexing

I just checked air pressure in my front tire, and it was at about 22 PSI. Now pressurized to 45 - front and rear (rear was 35). Maybe that's a factor. I've filled the front tire once before. Seems I have a very slow leak. Maybe that contributes to the wobble?

**EDIT #2**

Just took it out for a ride. Much more stable. An Audi decided to race me. I pushed it very fast - to nearly 120 MPH and got a slight wobble - but controllable.

I think that maybe the bike is just designed unstable. Any flick of the handlebars develops into a resonant wobble at any speed. MAYBE I flick the bars a little during shifting.

Best idea is that I should keep the tire pressure up and tone down my aggressive riding style.

My 95 did the same thing and I did 1 thing and only 1 thing.I put progressive springs on it.That's it,problem solved!!

 

[Lotsokids]

I found some Progressive springs. I'll try to get those. It's not easy getting parts in Hungary.

ALSO, I need some help... Can you guys check your bike and look at how much of the fork is protruding through the upper brace at the very top? Compare to mine in the photo below. I've seen some other V-Max's with much more of the fork through the top.

The reason I wonder about this is during a wobble, it looks / feels like it may be in the forks (yeah, my wobble came back today). When I flick the bars to generate a wobble, it appears there is an opposite resonance between my bars and the front wheel.

My reasoning is that if the triple tree is lower, it will support the tubes better and allow less flexing. Just a thought. :confused2:

 

[Traumahawk]

You can slide the forks up in the trees about an inch. Any more than that.....especially with the soft stock springs....will cause the bottom of the fender to hit the bottom of the radiator when you really grab on the brakes.

Sent from my SCH-R890 using Tapatalk

 

[jfeagins]

Right there is your whole problem. See that bug spatter on your right side cable mid way up, near the frame tube? If there ain't a similar spatter on a cable to the left side of center, the whole bike will want to wobble up a storm. GO GET THYSELF ANOTHER BUG!!!!!

Ride that bike and don't be deliberately trying to generate any more wobbling. :biglaugh:

In this video, the narrator says to end any weave, simply lie down: Who knew? :confused2:
https://www.youtube.com/watch?v=fvsDIq3WwVA

 

[Lotsokids]

In this video, the narrator says to end any weave, simply lie down: Who knew? :confused2:

Yes, I saw that video before. I've tried that, but no real improvement.

That looks exactly like my wobble, though.

 

[brad bruggeman]

I found some Progressive springs. I'll try to get those. It's not easy getting parts in Hungary.

ALSO, I need some help... Can you guys check your bike and look at how much of the fork is protruding through the upper brace at the very top? Compare to mine in the photo below. I've seen some other V-Max's with much more of the fork through the top.

The reason I wonder about this is during a wobble, it looks / feels like it may be in the forks (yeah, my wobble came back today). When I flick the bars to generate a wobble, it appears there is an opposite resonance between my bars and the front wheel.

My reasoning is that if the triple tree is lower, it will support the tubes better and allow less flexing. Just a thought. :confused2:

Can't really tell from the angle,but the CAP ONLY is all that is above on mine.

 

[brad bruggeman]

Yes, I saw that video before. I've tried that, but no real improvement.

That looks exactly like my wobble, though.

Did you notice that he is not on a vmax.All bikes makes and models have different characteristics.What other bike has a power boost at 6,000 rpm?Just saying!

 

[DMAN999]

Can't really tell from the angle,but the CAP ONLY is all that is above on mine.

That's how it is when it's still in the stock position.
I slid mine up 1" in the triple tree until I added a radiator cover then I had to move it to only 1/2" up in the triple tree so it wouldn't hit the new cover under hard braking.

@ lotsokids,
Did you ever let some air out of your tires ?
45 PSI is way too much air in our BIAS ply stock size tires.
Try setting the front at 33 psi and the rear at 36 psi as recommended in the manual and see what happens.
I'd also take the fly screen off, quite a few guys have said it made their Vmax unstable at high speeds.

 

[Fire-medic]

Looks like a GIVI screen. I don't think the screen of that size will contribute significantly to wobble. A larger one, probably but at what are illegal speeds in the USA. We always observe posted speeds.

If you're 200 lb + ready to ride, don't lower the forks in the trees (my advice, I'm not a mechanic). I'd change the fork oil, but since you're talking about springs, do it then. Check the factory manual about the correct sequence for tightening the front suspension and steering fasteners. Do the torque specs too, of course.

 

[Lotsokids]

Well, to this point, I discovered there was zero pressure in my forks with stock springs. Serviced to about 12 PSI in both now. It's been raining every day since, so not able to check if that made a difference.

Also, I ordered a set of progressive springs. Unfortunately I live in Hungary, but I have a trip to the U.S. soon, so I'll bring those back when I return to Hungary.

DMAN999 - I have not let out any air from my tires. The front has a very slow leak anyway. Low pressure seems to have a negative consequence. But there are so many factors involved in this... I could be jerking the bars while shifting, the wind, etc...

 

[Fire-medic]

Air in the forks will help greatly. So will a fully-inflated tire. I would not ride on a leaking front tire. If it suddenly fails, you are going to be riding across the asphalt ('surfing the tarmac') w/o a bike underneath you.

The fork springs should help greatly, as will new fork oil.

 

[MaxMidnight]

Can you guys check your bike and look at how much of the fork is protruding through the upper brace at the very top?

The top of my fork tubes are level with the top of the top yoke

When I flick the bars to generate a wobble, it appears there is an opposite resonance between my bars and the front wheel.

This is normal and why counter steering works the way it does. It is called Gyroscopic precession. Have a look at the video and you should see from the initial demonstration how a wheel reacts when a force is applied to the axle via the handlebars.

My reasoning is that if the triple tree is lower, it will support the tubes better and allow less flexing. Just a thought. :confused2:

You would be correct that the structure of the forks would be stiffer if the distance between the top and bottom yokes was increased. However, just dropping the tubes through the yokes will not increase this distance.
It will also have the effect of reducing the castor effect which will make the bike less stable in a strait line and may increase the likelihood of a speed wobble or in the worst case scenario introduce a tank slapper.