V-Max Speed Wobble (ran it up to 115mph and...)

[MaxMidnight]

I have been told the wobble is caused by the front and rear tire being slightly out of alignment due to the drive shaft. Individually the tire alignments track true but they are offset of a shared datum. This would also explain why extra weight farther back from the center of gravity would reduce the wobble. I wonder what type of experiment could be done to prove this theory? Hmm. Now I have something to spend my weekend on...

If that were so then all Maxii would exhibit the condition, which they don't. It would also affect all other shaft driven bikes which as far as I'm aware, is not the case.

Rear wheel alignments on shaft-driven bikes are fixed, if I am not mistaken, whereas on chain-or belt-driven bikes, the rear wheel is completely adjustable.

Correct with OE hardware but some movement can be effected if the fixed (drive shaft side) swinging arm pivot is replaced with the adjustable one from the other side. This will allow the s.arm to be moved over a small amount.
I did buy one many moons ago but as I've never had the problem didn't bother to fit it..

Don't recall if I have posted the attached in this thread or not but just in case...

 

[Shuriken]

If that were so then all Maxii would exhibit the condition, which they don't. It would also affect all other shaft driven bikes which as far as I'm aware, is not the case.

Don't recall if I have posted the attached in this thread or not but just in case...

There are some interesting thoughts for sure in that document you posted. Reading the thought process regarding the replacement of the rubber washer is definitely interesting. I would love to know why the engineers included it. Could it be a way to reduce vibration into the bars or to try to eliminate steering nuts from loosening at the possible expense of high speed stability? Also the idea of using adjustable swingarm bolts on both sides is interesting, although we may only be talking about an adjustment of maybe a mm or two. ?

More than one of us can absolutely confirm that the instability is decreased with added weight to the bike, especially when adding weight over the rear wheel. This has been so obvious in my own testing that I would be willing to try adding a storage box to the luggage rack and filling it with 75lbs of weight, at least for high speed runs.

Another thing that has been confirmed by more than one is that pushing equally forward on both grips stabilizes the wobble. Some have reported the same by pulling equally backwards, but forward works on my bike. These actions seem possibly to simulate the effect of a steering damper. Full disclosure though: I don't think doing this is permanently a safe thing to do because it requires a lot of effort and the bars must be held even until the bike slows enough for the instability to stop.

These 2 things, 1) adding weight, and 2) evenly pushing the grips forward have had the most impact on fighting the onset of the weave.

1. I have carried over 50lbs in a backpack and while this did help, it is nowhere near as helpful as just adding a passenger. No contest. So this continues to make me wonder if the added weight for the passenger in reality just sags the rear suspension more than the front, or even flattens the rear tire profile due to weight, which in tune, if I am not mistaken, changes the trail angle a few mm, making the bike more stable at speed. It might be possible to test this theory simply by riding 1 up on rear suspension which is a half-inch shorter, or installing a lower aspect ratio tire. Wouldn't this be great if fighting the wobble could be as simple as installing 0.5" shorter rear suspension or different tire?
   1. I have found references that tire aspect ratios and profiles absolutely affect steering geometry.
   2. In general, this is a good writeup on motorcycle steering geometry: "The bottom line here is that the more rake and trail we have, the more stable the bike will become, although both steering and maneuverability may suffer for it. Conversely, when rake and trail are reduced, the bike will steer quicker and become more maneuverable, though it’s usually at the expense of stability."
   3. From the same article: "Sliding the forks down in their clamps to give them a shallower angle relative to the pavement increases rake and trail, as does installing a shorter rear shock to lower the back of the bike."
   4. Does the added weight change trail angle or does it change tire profiles or does it stabilize the steering head bearings, or all of the above?
2. Pushing forward evenly on the bars makes me think of the commentary in your document regarding the rubber washer. I can't necessarily feel any odd movement in the steering head per se but it would be an easy-enough test to ditch the rubber washer with the idea of making the steering head more solid, based on the observation that pushing forward on the bars calms down the instability. The only other related commentary I've read is that this test may indicate that the bearing assembly may be walking inside the head tube...

Maybe only a degree or 2 of steering geometry is all it will take to settle out the bike...

 

[Shuriken]

Maybe only a degree or 2 of steering geometry is all it will take to settle out the bike...

I raised the front end about a 0.33 inch and did a ride test.

If it made any difference, it wasn't much... hard to tell. The bike tracks true and straight but is still hyper sensitive above 65. I don't dare ride it faster than 95 in case I sneeze... lol

I did notice at 65 when shaking the steering head while sitting on the rear seat that the steering is more settled.

After a 5mi test ride on the interstate, with fully warm tires, I noticed how soft these tires get. I can flex the rear tire by just grabbing the rear and firmly wiggling it. I had no idea how soft a motorcycle tire can be.

Seeing the affect this causes on the bike when on its sidestand is interesting. Seems like it induces a weave over the bike from rear to front, but I can't find any loose parts.

I'm beginning to think all of the components in system add up to flex and slop at speed...

 

[Shuriken]

https://www.vmaxforum.net/threads/high-speed-wobble.29380/post-451841

I read this entire thread....

Last message was an idea about springy handlebars and this made me consider that on my bike. Never thought of that as a possibility but the OP hasn't posted to the thread since.... hope he's ok...

It did make me rethink the front end again.

Here are 2 easy tests. With the bike on the centerstand and while sitting on the bike, the bars can be shaken to test overall looseness in the front end. The forks can be gently compressed as well by simply rolling the tire back and forth.

My 85 front end feels in general, maybe too sloppy. There is noise of looseness that sounds like it's in the forks. Might just be spring movement or maybe not. No, it is not caliper noise...

Also, jiggling the bars to lever the wheel really induces a springy feel. I have no baseline of normal without someone else testing and reporting back.

Anyone else willing to try these tests? I know it's difficult to describe or visualize feel, but here are some vids.

 

[brian hicks]

Yesterday I lowered the front suspension by 1 inch and took the bike to 110Mph, so it seems to have helped slightly. When I bought the bike last year I couldn't go above 85.

 

[brian hicks]

I have noticed that I can reduce or exacerbate the wobble by means of the throttle which could possibly indicate that an imput from the shaft drive is causing the frame to twist.

 

[Woody]

Have you checked motor mounts yet ?

 

[Shuriken]

Have you checked motor mounts yet ?

I did some rudimentary checking last night, as well as right-side frame bolted joints. I didn't find anything unordinary upon cursory inspection.

 

[Shuriken]

I have noticed that I can reduce or exacerbate the wobble by means of the throttle which could possibly indicate that an imput from the shaft drive is causing the frame to twist.

Certainly the throttle can induce all kinds of issues, as well as ham-fisting the clutch and brake. I've been paying much closer attention lately to how I operate the controls.

I really think if a few owners can do the tests I did in my videos, I could get some baseline idea. I am beginning to think that there is just enough fork play, combined with handlebar flex, plus the softer Shinko 230 (with sportier profile) that the front end is over-sensitive and a little sloppy.

Some parts of the 85 forks, such as copper bushings, are not replaceable. At least I can't find their part numbers. If they are indeed too sloppy, only a swap with the newer front end (triples, forks, brakes, fork brace, etc.) may solve the slop.

I can easily feel the frame and swingarm limitations at speed in curves. But what I think I can feel happening is the sloppy front end just starts the problems, which then get translated through the frame and to the rear. The problems may then translate back from the rear swingarm and suspension and frame back to the sloppy front end. So I feel like I need to focus on the front end first before walking backwards again.

By sloppy, I mean the front end feels too flexible. Sloppy doesn't mean loose bolts. Everything is tight and torqued. No low speed wobble at all. I can remove my hands from the bike and hold a nice line. If it were possible to ride 110mph on a flat surface in a vacuum, with NO inputs, the bike might track just fine. Any slight input from bumps, wind, buffeting, lane changes, or riding position changes can and do induce the uncomfortable onset of weave/wobble.

The most recent test was to experiment with only rear tire pressure between 30 and 40psi. Higher pressure seemed to make the problem worse. One other thing I noticed is when I removed the ME880 rear tire and compared it to the Shinko 230, the ME880 was a heavier and thicker tire. I think the 880 for whatever reason looked like it had a more robust cross section. The front tire was similar. Yes, I actually cut into the tire with a disc grinder and observed the cross-section. The ME880 tires were thicker.

I don't dare lower the front end. From everything I read about steering geometry, and from the article I posted before, lowering only the front end might make the bike less stable at speed and more performant in turns. It also may shift more weight to the front end. I've found the bike seems more stable by shifting weight rearward, but no 2 bikes are identical I guess:

"The bottom line here is that the more rake and trail we have, the more stable the bike will become, although both steering and maneuverability may suffer for it. Conversely, when rake and trail are reduced, the bike will steer quicker and become more maneuverable, though it’s usually at the expense of stability."

I can try to firm up the bars and grips to take some of the springy behavior off of the steering head but that won't solve any slop in the forks.

 

[Shuriken]

Yesterday I lowered the front suspension by 1 inch and took the bike to 110Mph, so it seems to have helped slightly. When I bought the bike last year I couldn't go above 85.

That sounds great, Brian. 110 is great!

 

[MaxMidnight]

Yesterday I lowered the front suspension by 1 inch and took the bike to 110Mph, so it seems to have helped slightly. When I bought the bike last year I couldn't go above 85.

That would have reduced the trail (castor) so I would have thought that if it was due to a front end issue it would make the steering less stable?
However, you may also have moved of C of G slightly further forward....

I have noticed that I can reduce or exacerbate the wobble by means of the throttle which could possibly indicate that an input from the shaft drive is causing the frame to twist.

...or it could be due to the torque from the pinion lifting the rear end which would also alter the geometry.

 

[MaxMidnight]

Some parts of the 85 forks, such as copper bushings, are not replaceable. At least I can't find their part numbers.

Part #'s 5 & 29? (3JJ2312500 described as 'Metal, slide 1')

 

[Shuriken]

Part #'s 5 & 29? (3JJ2312500 described as 'Metal, slide 1')
View attachment 94907

Thanks for that Steve! I've seen that schematic before but must have seen a different one or missed that part. I took a pic of my fork internals a couple of pages back. Maybe parts 7/31 and 5/29 are promising. It looks like they do call it a metal slide and I looked up the image of that part number and it does indeed look like the part.

Sean has said normally those parts shouldn't wear out unless the forks were too dry internally but it may be worth a shot. I will see if I can pinpoint the source of the clicking I hear when I rock the front wheel unless someone else doing these tests tells me it's normal and move on to something else.

 

[MaxMidnight]

I will see if I can pinpoint the source of the clicking I hear when I rock the front wheel unless someone else doing these tests tells me it's normal and move on to something else.

Pads moving in the callipers?

 

[brian hicks]

Mine also clicks If I hold the brake and force the front end to compress whilst the bike is stationary.

 

[Littleschipper]

I have a 2002 and when it was fairly new and bone stock (I am the original owner, over 40k miles now) I had the death wobble at about 120mph when I was trying to see just how fast I could make her go. Almost pooped my pants! On an older V-Max forum the steering head bearings were cited as an issue. I tightened them just a little as recommended, and also about the same time I won a set of Progressive Suspension front fork springs at the annual VMOA meeting in Johnstown PA. I admit I almost never go that fast anymore but after those changes the wobble didn’t come back. My forks have no air in them because of the new springs (as recommended by Progressive Suspension) and everything else suspension-wise is stock. The rear springs are at the the highest setting, 4. Note: at my age now I don’t push my luck with high speed blasts!

 

[Shuriken]

I tore down the front end again (removal of handlebars and upper triple tree bridge) with the intention on inspecting and testing and re-torquing the steering head bearings. I couldn't see any bearing issues or other anomalies. I reassembled and torqued the head bearings too loose on purpose. A quick ride test was quite revealing: the front end couldn't even hold a line at any speed without head shake and wobble. Never exceeded 45mph because the steering head shook at all speeds.

This was an interesting test. I was not expecting this, even with loose head bearings. I had anticipated the 45mph deceleration wobble but this was pretty interesting to see the front wheel shake instantly at all speeds. I'm really not sure if this is supposed to happen but if it is, this is a pretty informative experiment. It illustrates to me that the steering head bearings must be configured almost perfectly for the bike to steer safely. Slightly too loose or too tight and the bike will misbehave. Substantially too loose and the bike can't even operate at any speed.

So I've tightened the head bearings and have done the bounce test. I'm erring on the side of too loose at the moment and will test again later.

 

[Fire-medic]

I'm interested to see where your experiments take you. It reminds me of that scene in Awakenings with Robin Williams as an MD treating people in a ward of patients with encephalitis as youngsters, who are now adults. https://www.imdb.com/video/vi2721233433/?ref_=ext_shr_lnk He'a applying for a MD job as a clinician, to provide medical care for these chronic patients, and he speaks about an experiment he did where he failed to get the results his experimental design predicted (his hypothesis).

You have been on a mission to improve the bike's handling, and I expect that with the dedication you have shown, at some point things will be for the better, and we can benefit from it with our own rides.

 

[wilks]

What I’m curious about is if anyone else has the kind of issues Shuriken has…..I know I don’t but I don’t ride around cruising over the ton at all.

In my experience you can actually fix things until they’re truly F’d up in some cases.

I have friends constantly fiddling with their bikes thinking they’re actually fixing things and all they’re doing is creating more issues.

Not saying that’s what’s happening here and I truly appreciate all the data logging.

I just ride within the boundaries of the motorcycle….works for me.

good luck

 

[Radioguylogs]

My '86 was unstable when I bought it. Sometimes it would even go into a weave/wobble in the middle of a 60MPH curve.

I serviced the steering bearings and now I have no problems. I have gone up to 120MPH, but only once. I do go 100MPH regularly....we have some open areas where it is not so unsafe.