daltore - The gear box has been fully tensioned for over a week now, and we haven't seen any deformation of parts. How was yours used - in tension or in compression? It's hard to explain, but the turnbuckle here pushes out against the two bolts, so most of the force is directed along its axis, instead of on the loops. If we ran it the other way (from a different corner, for example) where it was pulling on the gear box to create tension, i would expect we might see the loops open up.
Don - It's hard to see in the picture, but that upper corner is supported on both sides by some pretty thick aluminum, and those plates are part of a bracket that attaches to the frame very securely. We aren't worried at all about the bolt sheering, and if it does happen to bend a little... we have saws and drills that can get it out if we have to use the box in another robot
