Bad Vibration at 60-85+ MPH..

[Blue Dave]

Welt,

I am not sure what to tell you. I did my measurements tonight with a stock idler and the SMA-8FP38-01-BK. The rubber area of both wheels ends up in the exact same place no matter which wheel is mounted either facing in or out.

Both wheels are completely interchangeable and symetrical with respect to the rubber area being centered over the 6005 bearing.

The "dished out" area on the finished side of the spoked wheel is non consequential because the "dished out" area begins about 15 mm inwards of the outer circumference and therefore it is not able to contact the 15 mm high track lugs.

 

[Iceman57]

I wonder if the Cobar track for some reason has the lugs mounted in a slightly difference place then the Ripsaw.

 

[welterracer]

SO i went out and walked down to the sled (which i have stored in my back shed..

I looked it over again.. and found the Real problem..

My track isnt adjusted properly.. its off about an 1/8 of an inch just enought to allow one side of the bogie wheels to come into contact with the rubber drive lugs of the track..

Sorry to get every one worked up for nothing..

I had run the sled several times on the stand to check to make sure it was strait.. but a good run down the trail has shown (new tracks do streatch at first)

Thanks for all the quick help

Brian

 

[SledFreak]

I ran these spoke wheels all last year in the inner wheels and have had no problem.

 

[nate007]

Hey, you got it taken care of.. that's all that matters!

 

[**sj**]

exactly....

dave

since my wheels sit 2.5mm lower.....you still think the cogs ( predator track) wouldnt/couldnt come in contact with the cogs?

 

[baggs66]

i also have the pioneer offset brackets and the inside rear wheels when faceing out needs bracket diameter turned down so that the c-clip that holds the bearing in wheel does not hit bracket which would hold wheel back from bracket which changes the offset and interfears with rotation

 

[ecopter]

Check this topic and find Port Yamaha's post midway down the page.

Jon

http://www.ty4stroke.com/viewtopic.php?t=61473

 

[Blue Dave]

I do not know anything about the Pioneer offset bracket, but if they move the wheel away from the rail (laterally) more than the stock mount then you will have an alignment issue.

However If they only move the wheel lower keeping the same lateral distance then you should be fine if you are using a 6005 bearing wheel. If you have a 6205 bearing wheel you will need to machine 1.5 mm off of the mounts.

Moving the spoked accessory wheel lower will not increase the chance of the "dished out" area hitting a track lug. This is because the inside of the track still contacts the rubber outer circumference of the wheel which only allows the track lugs to contact the wheel up to about 15mm inwards which is where the "dished out" area begins.

 

[**sj**]

i also have the pioneer offset brackets and the inside rear wheels when faceing out needs bracket diameter turned down so that the c-clip that holds the bearing in wheel does not hit bracket which would hold wheel back from bracket which changes the offset and interfears with rotation

I did turn down the body of the bracket diameter wise....it's square and the center opening was too small for the block shaped mount to fit it...never thought of the c clip though...i beter go look..

 

[**sj**]

circlip clears machined mount thanks to Jordan again lj452

 

[welterracer]

Well i readjusted the track today... and checked it several times..

I also checked all the bogie wheels and everthing looks great..

Took it for a ride, and i still have the vibration.. we only have 2inches of snow.. so its hard to get it to that speed for long..

Could my studs be causing my vibration.. i only used 144 studs with all double backers and because i only used 144 i had to leave every 5th row out.. so i wonder it that is going to cause the track to be out of balance (kinda like a car tire)

Anyone have any Ideas??

 

[KnappAttack]

Brian,
Take all the studs out, then you will have your answer. I already know the answer to your dilemma. I have experienced it firsthand.

I first took out the outside rows, still vibrated. Came back and took out all studs, no vibrations! Had 3 sleds here show the same phenomena, 2-Yamaha's, 1-Cat.

It's the reason I now run the Iceripper XT. Smooth, fast and NO VIBRATIONS!

 

[welterracer]

removing them isnt the answer...

finding out why they are vibrating is..

Ive never had an issue like this on the past 4 sleds ive owned and studded..

 

[Cobalt]

Welt you may have excited a natural or resonant frequency by installing the double backers. A natural or resonant frequency is excited by a forcing function that excites a natural frequency. The added weight may be resonating some part of your sled at a certain speed or Rpm (Cycles per minute). The fact that it is vibrating at a certain speed (Critical Speed) is a STRONG indicator of my theory. The other thing that could be an issue is that you have a crack in your sled or suspension which would lower your critical due to less stiffness or damping.

I have attached a video that shows how wind (forcing function) excited the natural frequency of a bridge causing a catostrophic vibration and collapse.

http://www.youtube.com/watch?v=j-zczJXS ... re=related

Best of luck!

Cobalt