New vmax owner headshake

[Saint]

Alright so I know how I'm spending my friday night! I'll take the back wheel off, check the axle to make sure its straight, then suspend the wheel and axle between jacks (cloth between jack stand and axle to prevent scratching?) and spin next to a straight rod. Then we should know if it is rim/tire related run-out or bike related.

 

[m-cman]

Attached are pics of my homemade wheel stand/balancer/run-out tester. Made from standard PVC pipe and fittings. The four t-fittings on the lower section with the crossbars are not glued. This allows the stand to be swiveled or pivoted in and out to accommodate various size wheel/tire combos. The axle holders are adjustable because when swiveled the axle location changes. In the picture the stand is at its widest position. That is a 170/60-18 tire on a Kosman 18" x 5.5" wheel.

 

[Saint]

Nice work, that thing looks great. You're right the axle is going to move on me with jack stands so I'll have to hold it still or clamp one end down while I spin and watch. I'll do the best I can tonight to see what's causing my apparent run-out. Would be great if all of this turned out to be a bad tire mount

 

[Saint]

So I removed the wheel and placed it between two stands, and used a straight broom stick for my reference. The tire seems to have a spot on every rotation that bulges out and hit the broom...seems there is about 3mm to 4mm run-out. I'm just wondering if that the tire is scrap, or if something like this is solved by remounting? and could this be my high speed wobble?
pics of course...sorry for the camera

 

[m-cman]

If you haven't already, try the same test on the wheel rim to be sure the wheel is straight. If so, you can have the tire remounted and balanced. If that doesn't work, you may have to buy a new tire. Tires can be out of round but it is rare.

My rear wheel is straight but the tire is not perfectly round. There is a slight wobble when I do the same test. Didn't measure it but not sure 3-4mm is much of a problem. Maybe someone else will know. :confused2:

 

[one2dmax]

3-4mm is quite a bit actually. I would get a straight edge (it doesn't have to be that big as your broom stick too) and hold it near the bead area. It could be a mounting issue, but your tire will have a raised section on the rubber to use as a gauge to see if it's evenly mounted up.

Sean

 

[Saint]

I won't be able to break the bead at home will I? The tire defintely has a raised area near the bead, that is where I held the broom near when I did my test.
I went for a good ride today anyways.. almost went through 2 tanks of fuel about 350km. Might be the last warm day of the year for Edmonton! Bike runs great, feels great too most of the time. Just once and a while I go to change lanes at speed and can feel a quick side to side in the handlebars. Other than that as long as I don't wind up to 200kph all the time I'm ok..
I honestly think the front springs will play a huge role in my issue. Radials I know would help greatly, I just hope they are still around (the rims I mean!) when my time comes to get them.
I think I'll take my rear back to where it was mounted and see if they can rotate the tire on the rim for me. Might not know if it helps til the spring though, looks like snow again next week!
Thanks again to everyone helping me with this all the way to page 13 now. I don't think I would have my sanity without this site.

 

[Cybergrizzly]

Isn't this cured by switching to progressive springs + fork brace. Use of a frame brace was also mentioned elsewhere.

 

[ddubb]

http://www.youtube.com/watch?v=OW-CmACI5xQ

 

[Saint]

I'll bring my thread back from the dead with some updates! Long cold winter here in Alberta but we've had a nice start to summer this year. So I've made a few changes to the bike since my last post.. I found a used cycle one off rim on eBay so now I'm running Pirelli angel radials (still stock front rim). I also picked up a used full hindle system in great shape for 300 bux..not that it helps my wobble but it sure sounds cool . I finished installing my progressive springs last weekend too. And I hate to say it, but with brand new radials balanced and progressive springs I still have a wobble that creeps up 160-180kph. I inspected and repacked my bearings and races a second time, they still look brand new (9000km on the bike now). So...im open to suggestions as to what to try next? I'll post some pics tonight when I get home as well

 

[Traumahawk]

Frame braces, solid motor mounts, or front fork brace. Any combination or all of them. People on here have had luck with a combination of any and all three.

 

[jfeagins]

Put it on the center stand. Spin the rear wheel and check for runout?

Did you check swingarm bearings? Good wheel bearings? Lots of little details can/will help you control some wobble.

 

[Saint]

when I bought the 17" rear rim I had the dealer throw new bearings in and balance the radial. The front bearings feel good. Not 100% sure on the swingarm but I've had the bike on its center stand and tried to move the wheel side to side, it's very solid. I'll check my new rear tire for run out tonight.

 

[jfeagins]

I had a new Dunlop one time that didn't quite seat correctly, plus had quite a bit of run-out from the factory. Fortunately, tires only last me avg 2k miles, and I moved on to the next new tire - fixing my problem that time.

 

[Saint]

The runout doesn't look too bad.. maybe a mm or 2. I did notice how close my tire is to my swingarm though lol, that 180/70/17 barely fits in there..and with the special spacer that came with my cycle one off rim, there is no chance to use a washer. Anyways I had a good ride tonight..I lowered my forks back to stock in the triple tree and it actually made it more stable at speeds so I'll leave that alone for now. The other thing that has made the biggest impact on my high speed weave seems to be the settings on my rear shocks. When I set the preload to 5 (stiffest), the weave starts much much sooner...145-160ish..and when I put it down to 1 or 2, it doesn't start weaving til about 180. I'll look into solid motor mounts or a frame brace I suppose, rear shocks too.

 

[Saint]

And some pics like I promised, I'll take some better ones outside some day

 

[jfeagins]

1 or 2MM runout is only as bad as 1 or 2MM runout. Enough to cause the bike to wobble. I'd guess that with a 4MM runout, you'd have at least twice the wobble you're now experiencing.

 

[Saint]

This is now my 3rd tire and 2nd rear wheel on the bike, none of them have been 100% true..do you suggest remounting and balancing the rear tire again?

 

[jfeagins]

You could try remounting it to see if it will seat up w/o any runout and/or rebalancing it. Chances are, you'll just have to wear it down and get another tire eventually, all the while knowing that you may have some high-speed wobble. In the mean time, you can certainly snug up your head bearing a smidge more to help you control what that tire is most likely trying to cause. Tons of small tricks (mentioned here and other threads) to help you control wobbling. Eliminating wobble itself will require a minimum of two perfectly round, and in-balance tire/wheels.

Keep in mind that a bad front tire/wheel could also be a contributing factor.

 

[Redbone]

This is now my 3rd tire and 2nd rear wheel on the bike, none of them have been 100% true..do you suggest remounting and balancing the rear tire again?

When you have them balanced are they statically balanced or high speed balanced?