Pneumatic Wheel Wobble

[thedude019]

im not sure how many teams have encountered this but the pneumatic wheels we ordered form AM are really wobbly. we tried getting the tire as full of air as possible still wobbles. we have a shooter built and the wobble causes a lot of vibration through the whole shooter and im honestly afraid of the wheel exploding and rubber flying around. it seems that the tire part isnt on the hub correctly but no matter what we try it still wobbles so can anyone tell me how to fix this

[ehfeinberg]

http://www.youtube.com/watch?v=88Ik-99grms Minute 2:08

Andy explains how to fix this issue pretty well.

[FrankJ]

Do realize pretty much any small pneumatic wheel is being for shooting Frisbees is being used way outside of its design parameters. So you need to make everything as good as you can. Make sure the supports for the wheel are beefy (highly technical term. If you can, use bearings on both sides of the wheel. do not depend on the motor bearing to support the wheel. Lunch with Andy (above) also points out the importance of balance at high RPMs.

We have been running our wheels with no air in the tubes just depending on the stiffeness of the side wall & centrifugal force.

[Jay O'Donnell]

We had this same problem with out prototype last week. I would suggest a number of things to check...
1) check whatever you are using to attach the wheel to the motor.
2) do what was already said in the video above
3) balance the weight of whatever is on the wheel to allow you to pump it up with a small piece of aluminum
4) make sure your shaft and bearings are straight (assuming that is your system)

Hopefully this helps, good luck!

[GDG 2337]

We used AM 8” pneumatic wheels last year on drive. 4 out of the 16 we bought had low speed wobble like you mention. We traced issue to the tires not being concentric.

[thedude019]

thank you so much for the help i really never thought of off setting the wheels and quick question does anyone know what the max rpm is for this wheel and is direct drive to a CIM to fast

[Oldbikerider]

As pointed out above, these tires often do not seat correctly on the plastic wheel rim first time. Soapy water applied with paint brush in the rim-to-tire gap of a deflated tire will help seat the tire bead correctly when it's re-inflated. Rinse, then let the water dry before spinning up the wheel because you want a firm grip of the bead to the rim seat, and don't get any water inside the tire

If the tire still wobbles, then try a new tire and/or tube. These are low speed wheels, and the production variations on carcass distortion and tread thickness won't be to the same standards as a high speed tire like an auto tire.

Relative to the tire misalignment or distortion, the valve stem won't be contributing much to the out of balance because it's at a much smaller radius, plus the rim is lighter where the valve goes through (because of the hole), and this partially compensates for the weight of the valve and valve stem.

Please be very careful adding balancing weights. If they get loose they will be a high speed projectile. If the tire won't balance itself, I'd say it should not be spun at speed as the out of balance probably indicates some sort of carcass "fault".

Graham.