Changing the iteration counts should also work in Chaos. As should reducing the timestep (by enabling sub stepping and setting the max substep tick). If these don’t work, maybe there’s a bug (please post a UDN if so).
We also have a non-linear joint solution that is quite a lot more expensive but is more stable. Currently you can only enable this system-wide (and not per asset for example) via a console variable, but you may find it useful:
p.Chaos.Solver.Joint.UseLinearSolver 0