Friction problem

Suggestions to reduce gearbox friction?? Need help in order for flywheel to actually run smoothly.

Make sure that the hole the high strength axel is coming out of is big enough that the axel doesn’t rub in the hole. If you have the ball bearings, use them, and if you have a blue motor cartridge, use that instead and decrease the ratio
(Edit: also make sure there isn’t a lot of metal on metal contact especially with that second axel, it looks like there might be some rubbing there)

Seems to me like one motor is trying to spin the other at a different speed (there is a different gear ratio between the 2 motors:

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Washers or spacers between metal and metal.


I agree with @Some_random_person, it doesn’t look like a friction problem so much as it does a gearing problem. You have 84 to 12 to 84 to 12, where you should have 84 to 84 to 12. Or something like this (minus jank)


HS shafts usually have a very high amount of friction. I would highly recommend using LS shafts for your flywheels and/or using ball bearings.


if you are using a 200 rpm cart, your flywheel is spinning at 9800 rpm. That is crazy fast and your motor will not be able to run that well. Also, is that a second flywheel motor?


Try and see if you can find a gear ratio that will spin the flywheel with about 3000-4000 rpm. That seems to be a good speed for most teams.
My team uses Gear Ratio Calculator
It’s a good resource

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Also check out using a no-cartridge motor. It spins at a max of 3600 rpm


Super lube would help, but like others are saying your gear ratio is too fast to be effective. I would recommend something around the 3000-4000 rpm range for a well balanced flywheel. Good luck!

A few ideas; drill out all axle holes, make sure pillow blocks and c channel are centered together; or try a gearbox-less motor 606x has a great you tube video explaining how this works.

Thank you guys so much! This is our 2nd year doing vex competitively so we’re still a bit unfamiliar with things. I’ll def communicate your advice to my team.

general rule of thumb, “less friction = less load on motor” try to reduce as much friction as possible. a good way to test this is to spin the shaft by hand and if the shaft spins nicely, which you will definitely be able to tell if it is, that means there is not that much friction on the shaft. you can also loosen up the bearings (black things with the three holes) and wiggle everything around till it spins nicely, then tighten everything back up.


Check motor power usage to determine if your changes are working and to what degree…

Makes great notebook entry.

Drilled out holes won’t hold the shaft. It will vibrate, oscillate, not run true, and power usage will skyrocket.

Ive had positive results from drilling out bearing flats

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I’d ask “why”. There’s plenty of clearance on an undamaged bearing. If drilling helped, that seems in indicate the bearing was damaged (smooshed, overtightened, etc).

if the hole is bigger than the shaft… if the clearance is too much, ESPECIALLY on a flywheel shaft (not normally under a side load) then precession sets in, the shaft starts vibrating wildly, speed drops, and motor watts max out.


Because it lowered the wattage use of my motors

I mean yeah, I figured that. What I mean is why did it… the bearings are sized to the shaft dimensions… so drilling’s not needed. If drilling dropped watts… it’s almost certain you have an underlying problem (bearing damaged, bearing misaligned, frame misaligned, etc). That is the thing I would track down, the root cause.

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