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130mph bike woobles???

7K views 40 replies 26 participants last post by  Louis 
#1 ·
i was doing 130mph. n my bike started to woble.(shacking) so i slow down to 90mph. then hit it again to 130mph and started to doing the same thing again. does any one have an explanation for this???:banghead: and a idea of how to fix that???
 
#4 ·
Some of the basics to check are front tire air pressure and the tripple tree fall away. Sometimes the fall away will get a little loose and it will result in high speed wobbles. I like to set mine on the tight side of the specs just for that reason and never had issues with wobble on mine.

Mike
 
#5 ·
I keep telling you guys that the source of the woobles, wobles, and shacking is the rear tire imbalance. Why won't anyone concur?

The 240 is wide enough to need dynamic balancing (two planes) versus static balancing (single plane). If you get a well balanced rear tire the wobble disappears.

I have had three different rear tires wobble at 100+. I now have one that has never wobbled up to 140. It was the only change made that cured the issue.
 
#6 ·
So would dyna beads take care of the dynamic balancing you speak of doc or are they static as well?
 
#7 ·
Stock I had the wobble. (Dunlops + static balance)

Switched to Avon Cobras with Dynabeads and no wobble.

Mounted F-model wheels with Perelli's and static balance (then the next day had to switch to a Dunlop rear at the dealer due to a flat), now the wobble is back.

I will be switching back to Avons and Dynabeads as soon as I can.
 
#14 ·
I had the same problem in my 09 DX , I used to have the stock Dunlop last week I replaced it with the 280 metzeler and while I was doing so I discovers that the rear bearings was in a bad shape ( rust) so I changed it and the dealer confirmed that the wobbling was due that ,I didn't test it in hight speed cuz I was afraid of hitting hight speed on a brand new tire,I didn't ride since then to try I will keep you posted once I know


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#15 ·
I had the same problem in my 09 DX , I used to have the stock Dunlop last week I replaced it with the 280 metzeler and while I was doing so I discovers that the rear bearings was in a bad shape ( rust) so I changed it and the dealer confirmed that the wobbling was due that ,I didn't test it in hight speed cuz I was afraid of hitting hight speed on a brand new tire,I didn't ride since then to try I will keep you posted once I know
Doesn't explain it happening on a brand new bike...
 
#17 ·
The heavy rear tire wobbles the entire motorcycle when it is not dynamically (2 planes on same axis) balanced on the V-Rod. The effect is that the frame shakes left to right to left to right to left to... The only thing that holds the frame from shaking is the nearly vertical steering axis at the front of the frame (steering stem). The front forks are the weakest part of the frame assembly because they are relatively short compared to the length of the main frame and much more flexible.

Imagine holding a long stick out in front of you from the end of the stick. Attached with a vertical pivot at the other end is a short stick. At the far end if the short stick is a wheel. Your hand simulates the rear wheel, the pivot simulates the steering stem, the short stick simulates the front forks, and the wheel simulates the front wheel. The entire assembly is the V-Rod motorcycle.
Now lower the wheel so that it is touching the ground. Shake the stick assembly (V-Rod) left to right to left...with your hand (rear wheel). The front wheel will not move left to right but the pivot will. If you had a strong dampener to prevent the pivot from moving, the assembly would not wobble until you exerted enough force to overwhelm the dampening device.

While riding, you are the dampening device that is attached to the front forks through the handlebars. As the rotational speed increases, the amplitude of the rear wheel imbalance increases. When enough left to right shaking overwhelms the dampening device (you), the front wheel wobbles.

Minimize the force (have your rear wheel balanced) so that it will not overwhelm you while riding to prevent front end wobble.:deal:
 
#28 ·
Rather than explain it again, let me just write that I experienced the wobble with three different Dunlop rear tires and a LOT of adjusting everything from engine alignment to rear wheel alignment to fork stem adjustment to front tire replacement/balance. NOTHING made any significant improvement until my fourth rear tire (an Avon that was given to me).

I have extensive experience in low and high speed dynamic balancing on industrial apparatus. I firmly believe that the first three tires were unbalanced dynamically, causing the wobble. The fourth tire completely eliminated the wobble upon installation and remains smooth after approximately 10,000 miles and subsequent replacement of the front tire (which had no effect either way).

I concede that the American-made Dunlops were defective (hurts my heart to admit it) and suited for low speed usage only (although I never asked to have any of them dynamically balanced). I have a Spanish-made Michelin waiting at my buddy's bike shop for me to wear out this Avon. If the wobble returns, I'll have it dynamically balanced. I will post the results in a new thread...
 
#33 ·
Dr Dave is right .... Balance, balance, balance

I work with rotating equipt on turbines, gensets, deep well vertical turbines and Dr Dave is right... until the balance is addressed, all other things just mask the true problem. If the tweaks done to the front forks, fork stabilizers etc ... "fix the problem," they are probably just altering the vibration coming from an imbalance at the rear wheel. The real problem is when the adjustments "amplify" the vibration of the "system," .... then you are screwed. Your wobble may appear at any mph, not just 130mph. It depends on where the system enters it's 1st, 2nd or 3rd critical imbalance stage. Until I changed my front tire, had the rear balanced & aligned, I was getting steering wobble issues at 95mph ... if you dampen the wobble through stearing area adjustments, you are not addressing the root cause of the problem.
 
#34 ·
Here are my two cents worth (warning: that may be all it's worth too):

Fact #1: Older VRods have a 4 degree triple tree offset (we all can see this when you look at the neck). Newer VRods (about 2007 or 08 to 2011) have a 2 degree offset. Newest VRods have a zero degree offset. Muscles have zero degree offset.

Fact #2: Triple tree offsets are built in for LOW speed handling advantage.

Seemingly (my two cents worth)...this is a BAD feature when traveling at extremely high speed. So bad bearings, loose fall-away, wide tire, narrow tire, Dunlop/Metzler/WTFever, big/skinny/naked girls on the back, doesn't really matter as far as I'm concerned.

Slow down or go to a track if you're on a VRod. I know that may not be as much fun, but I've wrecked at 130mph on a track from a high speed wobble and it surely isn't fun...and someone was killed last year at a Texas Land Speed event on a Destroyer. Why? It's my understanding that he was using the stock 4 degree offset trees and experienced a high speed wobble at the half mile marker and went down. And yes it's possible that he had hit a rough bump and tweaked the stock wheel out of true, but I don't think so from what I'm hearing.

I agree with Dr Dave...dynamically balance your wheels...use technology to your advantage! Reduce some risk that way.
 
#35 ·
....
Fact #1: Older VRods have a 4 degree triple tree offset (we all can see this when you look at the neck). Newer VRods (about 2007 or 08 to 2011) have a 2 degree offset. Newest VRods have a zero degree offset. Muscles have zero degree offset.

Fact #2: Triple tree offsets are built in for LOW speed handling advantage.

Seemingly (my two cents worth)...this is a BAD feature when traveling at extremely high speed. So bad bearings, loose fall-away, wide tire, narrow tire, Dunlop/Metzler/WTFever, big/skinny/naked girls on the back, doesn't really matter as far as I'm concerned. ....
Your facts about triple clamp angles are OK but you're wrong about the resulting frame geometry.

The reduced 2° triple clamp angle in the VRSC models with a 240 tire (this started with the 2006 VRSCSE2) resulted in a longer trail of 4.6" (the earlier models with 4° triple clamps have a trail of 3.9" and the VRSCR models, also with a 2° triple clamp angle, had a trail of 4.3").

Comparing two bikes with the same steering tube angle, the one with longer trail will have more high speed stability and slower steering response.
 
#39 ·
I reckon any wheel wider than 200 will need dynamic balancing at that speed .
Have you had you wheel dynamically balanced WITHOUT A TYRE ? The forces are huge for the heavy portion of the circle to take over the centre of the track of centerline rotation. Its a Gyroscopic Effect . This is your wobble you speak of .
Me , well with my skinny old 180 back tyre I dont have the problem , but I dynamically balanced it anyway , both without a tyre and with the tyre .
Skiddin
 
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