@Jonny5 - Thanks, I'd run across this formula before, and you've confirmed it.
The one aspect that complicates the matter even further, is that the crossover sleeve that sits between the top/bottom sleeves is longer on one end, towards the smaller (primary) spring by default. With that sleeve being longer towards the preload nut, the amount of travel before the secondary rate kicks in is very short - even less as preload increases. This is where I've run into issues in scenarios where I've raised the ride height to the point where the secondary spring rate kicks in with very little dampening.
The tinkering I now have in mind is:
1) Reversing the sleeve to increase the travel on the primary to see if this provides a more lenient path try different combinations.
2) Reversing the sleeve and moving to a stiffer small spring, softer large spring - with the goal being a softer early and mid dampening phase, and a stiff final stage.
I should probably move this to a dedicated topic, but since it was born of Fred's theory I thought I'd at least mention it here with some relevance.
This very issue is why I really don't mess with the dual spring setup. What you need is a secondary collar that is threaded on the shock body (think of a preload nut that is small enough to fit inside the spring, but large enough to securely stop the coil slider). If you had this secondary collar, than fine tuning the point at which your primary spring kicks in would be very simple and easy to do. In this case you would want the lower spring to be the heavier of the two- this would yield a soft, compliant initial to midrange spring rate, and a firm rate when approaching full compression. As of yet, no one makes a shock that can effectively accomplish this type of setup. Almost justifying a small cnc machine for my basement.
