ORIGINAL: Perry S.
Torsion bars or 'torsion springs' are a pretty old concept. If yo have a TB suspension tank that starts to sink after use then the TB's are underdesigned and they are being being pushed beyond their design limit. Properly designed they should always return to their beginning point. That is unless the yield strength of the material is exceeded.
If your interested I could send yo the equations for their design.
Perry
My problem with the PzIII suspension was that it always sat with the battery in it and would sag to that side a bit. Since I now store it with the weight off the tracks, it no longer sags when I do run it. I figure letting the springs hang with the weight of the metal roadwheels allows the spring to maintain it's original shape.
The KV-1 rear springs were basically bent from being compressed when I received it, but even if they were not, they are still not strong enough to support that long arse with metal gears and motors mounted. The last spring is before the gearboxes, so that's a lot of added weight and leverage on those rear wheels.