BobR wrote:....the driver told me he had "never" pulled a trailer that tracked so well or rode so smoothly. He wouldn't have said that if he pulled it before I mounted the shocks...
I can believe that.
I think the rubber torsion axle has a lot going for it, but it's a bit generous to describe it as combining spring and damper in one unit. More realistically it combines a spring and a little damping, but not the effective damping that is provided by fitting a proper telescopic shock, like Bob's example. Torsion axles can be fitted with dampers, but I've only seen it on European travel trailer axles designed to take them from the start.
I'm with Madjack on the durability of torsion axles - having worked on trailerable boats, where some owners regarded even pumping up the tyres as an impossible burden, I've never seen or heard of a torsion axle suspension failure - but plenty of hub bearings and tires!
Andrew