Shaky Flywheel

I’m having a lot of trouble with my flywheel prototype being unstable as it runs. It’s a four motor single flywheel with two 5" wheels and a 1:35 gear ratio. At low speeds, it runs pretty well, but when it gets faster, the whole system starts jumping around like a jackhammer.

I want to know what is causing the shakiness, and what I can do to fix it. When I remove the two wheels, everything runs perfectly, so I’m guessing the problem is with weight and balance. Right now, I don’t have access to any high-strength shafts, and I can’t attach the flywheel mechanism to any base. If anyone has any suggestions, I’d love to hear them. Thank you for your time.

Could you provide a picture of your setup?

One thing I would check is if the shafts are fully supported right up to where the wheels are. If your flywheel is mounted on the shafts with a few inches of spacers between the wheels and gearing, that could cause some problems.

Below is an image that shows how I supported the shaft, though I would suggest you make sure you do it on the top and bottom.

I found a really helpful thread once at the beginning of the year on this but I can’t find it now anyway my flywheel went earthquake on me until I switched the bent axel but make sure everything is lined up, straight, and not damaged. Remember the faster something spins the more imperfections will haunt you. If ALL else fails (and it really shouldn’t) try putting something (maybe a zip tie) on the of the flywheel’s spokes and if the shaking is better, add more zip ties if the shaking is worse take off zip ties for basically every spoke. Remember this is supposed to be a last resort.

I’ve been working to keep everything lined up and straight, just the usual manufacturing imperfections.

That likely is causing a lot of the problem. Since it was just a prototype, I didn’t think too much about supporting the shafts, so the bottom shaft has several inches between the flywheels and any support. I’ll take your suggestion and see how it works.
I may be able to post a picture tomorrow.
Thank you for the help!

You are correct. It is the weight.

another issue (in addition to the others already mentioned) may be that at high speeds the rubber tire on the wheel is expanding and creating vibrations due to the high rpm needed for a single flywheel. You may want to consider adding either zip ties or rubber bands to keep the tire on the wheel.