We are planning on doing a 4 wheel drive bot, however
would 4 CIMple gearboxes with one CIM in each be better then just running 2 CIMple gear boxes with 2 motors each?
I would assume the power output would be the same? but not a 100% sure.
Any input would be helpful.
4 gearboxes has 4 times (gearbox friction and losses).
4 gearboxes also has 4 times (gearbox weight).
They also take up more space.
But you might get away without needing any chains to drive the ‘other’ wheels (= less weight).
Think for yourself the advantages and disadvantages then discuss it with a mentor. Only you can decide what’s best
The first thing you should think about with 4 whl drive is that the robot will turn with difficulty. Have you tried it on carpet with the kitbot parts? Not the same as driving on a slick tiled floor or hardwood gym floor.
In addition, powering drive wheels independently works until the robot lifts in a pushing match. Then less power is transferred to the carpet. You will probably be better off (more competitive) if you use dual CIMS to each side. Do a search for 6 whl drive on this site. There’s tons of info on this topic.
In addition, AndyMark and Banebots have dual CIM transmissions available, saving weight from a four transmission setup. 
Well for having one gearbox with 2 CIMs on each side, we would need to run longer chains. Would having the longer chains have problems falling off in competition?
So running one gear box each side would give more pushing power then running one gear box on each side?
One gearbox with 2 CIMs on each side would, overall, deliver more power to the wheel(s) still in contact with the carpet. However, traction then will come into play.
If you’re using #35 chain, it is more forgiving. Allow for chain tensioning as well, and be certain your drive and wheel sprockets are aligned. Some teams use #25 chain, and wheel alignment and chain tensioning are much more critical to minimize potential chain walk off from a hard hit from the side.
Thank you for the replies, i think we might just go with 2 gear boxes and 4 CIMs.
I assume #35 comes in the kit?
Chains shouldn’t be a problem as long as they are tight enough and they are VERTICAL! I can not stress enough how utterly impossible it is to use long horizontal chains, as we bent our sprocket shafts last year trying to get the chain tight enough to counteract gravity tendency to pop the chain off(ultimately permanently disabling our robot). As long as you have the room chains will work (Even though i mortally despise chain now)
Thanks for all your input
Now we just need to finalize everything
Decisions Decisions Decisions…