I'm curious what the second smaller spring is for. I can see how a linear and non-linear spring would work, but just don't see what the purpose of dual springs would be. Here's a few examples. Hopefully no one gets mad that I'm using these pictures...

 

Small spring is a helper to allow changing ride height without changing main spring preload.

 

and it also decreased lots of vibration on the road...

 

helper springs keep the load constant on the spring even on hard turns and apexes even when there is 0 load applied.
keeps them from bouncing around possibly binding.

 

I still don't understand this... Whats the point of having that small spring there? OEM coilovers have one spring and they don't vibrate, they have constant load even when 0 load is applied, they don't bind...

Also, why would you need this spring to keep the preload?? This makes no sense to me... there are many high end coilovers without this second spring. Does that mean they lose the preload when they adjust the height? I don't think so...

 

Those springs are fully compressed when the car is on the ground.

 

This makes a little more sense. So I'm assuming the spring allows for a longer stroke?

 

No sh!t.