Falcon 500's binding with 11t Pinion Gear in 3 CIM Ball Shifter

Currently assembling a 3 CIM Ball Shifting Gearbox from VEXPro with 3 Falcon 500’s with 11t pinion gears. We are running into a binding issue inside the gearbox as it seems the motor shaft needs to be torqued away from the gear it engages with inside the gearbox. If I am reading VEXpro’s website right, the 11t pinion should work with our setup (pictured below). Any ideas on why this is happening and if this setup is possible to run? If so any ideas on how to fix this?

Yes, any of those 3 pinions are drop in replacements, so they should all work the same. Unless there’s a manufacturing issue, it’s probably not the pinions themselves giving you problems.

Have you double checked to make sure the proper gears are in the right places? Have you fully assembled the gearbox (sometimes with just one side of the shaft supported it’ll bind)? Have you lubricated the gearbox (this should help, but it shouldn’t bind before you grease it anyway)? Any pictures of your setup / the gearbox internals would be helpful for diagnosis.

Just to confirm, are the pinions you are using for sure 11T with 12T distance that either came with the gearbox or were purchased separately? One or more plain 11T pinions finding their way into the gearbox could definitely cause issues.

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Are you sure it is a pinion clearance issue? We had binding issues initially due to the Falcon mounting screws. Long screws can drag the rotor.


I have been told we bought these off of CTRE. Are these different than the ones you would get with the gearbox? Looking at the dimensions it appears they are the same.

We are using 10-32 x 1/2" machine screws, so I don’t think this would be the problem.
EDIT: This actually might be the problem.
ANOTHER EDIT: This was the problem, thank you for everyone’s help!

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We have double checked the gears, fully assembled, and lubricated. It’s is looking right now that our falcons are not free spinning which is probably due to our motor mounting screws being too long. We are looking into this now to see if this is the case.

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