Vex Pro 3 CIM Ball Shifter WCD 3rd Stage Kit with #35 Chain

Currently, our drive is a 3 CIM Ball Shifter with a WCD 3rd Stage Kit with #25 chain. In the WCD part of the gearbox, we have 2 18 tooth #25 sprockets but we were wanting to switch to #35 chain. When looking at the CAD, it doesn’t look possible to run 2 #35 12 tooth sprockets with the WCD addition because of the width and the chain will not fit. Are we missing something or is the only way to use #35 chain with the 3 CIM Ball Shifter WCD 3rd Stage Kit to have only 1 #35 sprocket in the WCD addition to the gearbox and place the gearbox at the end of the drive?

We tried using #35 chain on ours and quickly realized that it doesn’t work without doing some modifications that really put the structural integrity of the gearbox at risk. You will need #25 chain.

We added half inch spacers and longer bolts to create the space for a double #35 sprocket.

We have modified a set of these to use 15mm belts. The 4 standoffs that hold the aluminum output plate need to be extended (as in, make your own out of round and hex stock). As the standoffs get longer, you should probably plan for additional support for the gearboxes.