A thread on this a while ago, led me to believe that the rebound spring should just be touching the stub axle, when the car is normally loaded. Have I got this right?
This good advice is based on the fact that any static pre-load on the rebound spring will work initially in parallel with upper compression spring, dramatically increasing spring rate until rebound spring becomes unloaded. A little difficult to get your head around as intuitively the two springs appear to offset each other or work in series. You have to consider they work on opposite sides of stub axle though.
Any rebound spring pre-load leads to the afore mentioned high spring rate which then reduces to a much lower linear rate when only upper compression spring is in play. This leaves initial harsh ride followed by soggyness as suspension compresses further, exactly what is not required.
A rising rate compression spring would be ideal with no interference from rebound spring, but not sure if such are available.