leaf spring tweaking

the springs I want for my duster are either no available, or way to expensive. so ive been looking into modifying my spring pack.

is there a way to figure out rates? like measuring individual leaves and doing some math?

what does clamping do to the rate?

some leafs have an additional half leaf on TOP of the main leaf. they state that this is to reduce brake hop. does this leaf add into the additional rate? does it actually work?

rubber or poly spring eye bushings and why?

sliders on a street car: yes/no and why?

car is a HEAVY 70 duster. some autocross, mostly street driving. currently running 70 duster 340 4 speed springs, which are way too soft. it bottoms cconstantly, and squats with the least amount of junk in the trunk or additional passengers.

If you are building leaf springs with used springs you will eventually end up with the same condition. Bite the bullet, save time/labor and buy new or have a spring shop build a set (which is cheaper than new here). All old Mopars had/have sagging springs. Plus, you will have new bushings, sliders and clamps.

The 340 springs are actually fairly new. Around 10 years or so. Not sagging, just that lowered and that much rubber. And too soft. Near as I can tell, around 110 in/lb. I'm thinking more around 160 is what I need. Arch is right, but I'm looking to optimize it while I'm in there.

Could you supplement the soft springs with an air shock or even adding bags?

Nope. Due to packaging, I don't have the room for bags. And air shocks on a duster tend to rip out the upper shock stud and corresponding chunk of floor. So it's building a custom pack....

DC used to sell "super Stock springs cheaper then stock replacements from Mexico. somewhere I have the leaf rate calculator but you also need to figure wrap up resistance.

Super stock springs would work, but I'd need two right side, and then have them dearched. It's the option I was thinking about before going down the rabbit hole of building my own.

Add a leaf or two. I remember seeing a leaf roller in a spring shop. I was used to camber or de-camber.

John Block has a calculator on his site leaf spring rate calc