Ball Shifter coupling not together??

We were assembling our ball shifters and I noticed that the coupling that links the pneumatic cylinder to the shifting linkage does not completely close over both half’s flat…where the screws go, it is nice and together but on the end there is a smaller gap, haven’t put load on it yet to see if it would be okay but thought I would ask you guys and see if anyone else has had a similar problem.
Thanks, Ronnie.


When properly assembled the coupler sides close flat together, be sure that the nut on the piston shaft is properly seated in the coupler (a flat face on the nut must be parallel to the wall of the recess in the coupler, otherwise there will be a split when assembled due to the nut not being fully seated).


We had that same problem. First, I thought it was students being careless. Then a mentor did the same thing. We ended up printing a few on the 3D printer. I increased tolerance on the nut by about .003. Seems to fit nice. We haven’t load tested them yet. That’s tonight.

Hmmmm. My team encountered same problem and solution. Our lead mentor (a real genius at design) noticed that original coupler tolerances for nut and bearing appeared off.

We have looked at hundreds of couplers here. Are you certain the nut is properly oriented? When the nut is properly rotated, the coupler fits on nice a snug.

It is a super tight tolerance, I have tried again and I do not believe that I have it right…can you provide a picture of how yours looks before you place the top clamp on the shaft?

Sorry for the quality, I just have my phone handy.

The Nut and the flats on the piston must line up.


Ours lined up. You have to have the nut nearly flush with the end of the threads.

This is intended, as it sets the spacing for the piston to plunger attachment to make sure the mechanism works correctly.

Hey we encountered one more problem Aren, The standoffs for the 3rd stage are not 1"…more like 1 7/8"…so they stick out farther, the gear and bearing no longer are contained and will need to have a spacer made to keep them on. The bigger problem is our belly pan that was machined based on specs and now we will have to cut belly pan to fit the shifters in.

It seems like you ordered the WCD version of the shifter instead of the regular version. The WCD one has longer standoffs so that you can put sprockets, belt pulleys, etc. inside.

Disclaimer: I obviously know way less about this than Aren does, I don’t work at Vex.

Correct, We did order the WC one…those are the instructions I am reading…that is why I am so confused.

Nm. Managed to look over the important detail of sprockets being put in place…that quickly closes the gap. Thank you for turning on the light bulp!
Thanks, Ronnie.