[Joe Johnson]

I am not saying teams should panic. I believe the BB transmissions are still a great bit of engineering. BUT, like all things they have limits.

I believe that the higher ratios are even useful, but more for speed reduction not torque increase. The output joint is the same for every ratio. If the torque gets too high it will break that joint.

Now to your questions:
Will a gas strut or other counter balance help? Yes it can but it is not a panacea. Counter balance is just flat out a good idea. Teams should do that regardless of what motors they choose.

Should you toss out the BB design and start over with a window motor? This is a tough question. The window motors are great motors too but they only have about 20W of power available. If you are doing some significant work with the motor, you will have to do it about 1/5 as fast with a window motor than with a BB motor. If you are using the higher ratio but you never stall the motor you are probably going to be just fine (try to limit impact loading if you can).

In rough numbers, I project that the 42mm gearbox will fail with repeated cycling loads of +/-350in-lbs. I project that the 36mm gearbox will fail with repeated cycling loads of +/-100in-lbs. If you can design your mechanism to keep your loads below these (with a safety margin that lets you sleep at night), then I think you should be okay.

Joe J.