Hot Rods Removing leaf(s) from a leaf spring

I often see guys say I removed 2 or 3 leafs from a spring. My question is how do you determine which ones to remove? Do you start with shorter or longer leafs? Which would
have the greatest effect on safety, on ride or static height? Logic would seem to say longer springs being removed would have more effect than shorter but is there a formula to tell
just how much? If I start with a 7 leaf spring and remove the 2nd and 4th shortest how much different would that be from removing the 3rd and 5th?

 

I haven't really tried to calculate the effect on which leaves to remove, but usually have kept the main, and next to it, then every second one after that.

 

I've always left the longer leaves and removed shorter ones, read somewhere that the shorter leaves were stiffer.

 

on a '47 Ford removed 2nd from top and 4th from top - each removal gave about 1/2" of lowering - but, springs were dearched & reversed eye too - brought fender down as close as possible to still turn wheels lock to lock without tires rubbing

 

I've had to remove leafs on every car I built to get the stance, or ride quality I wanted. More often up front on solid axle cars, than in the rear; but both sometimes.
I can't tell you how much a certain leaf lowers a car, or changes the ride, as it's not a set amount. I have found that removing the shortest leafs does very little to lower the ride, or soften it. The longest leafs have always given me the greatest change in stance and ride when added or removed.
My current build on my '39 Chev coupe was too high in the rear, and too stiff up front. I removed all but the main leaf in the rear, and then took spring leafs from a 1958 Chev pickup front spring pack, and added 3 to the rear spring pack. They were thicker than those I removed, and had a flatter arc, so I hoped they'd lower the car. They did, but not quite enough, and I didn't want to end up with a mushy ride. So instead I made lowering blocks from 1"x2" box tubing, and welded them to my axle perches to give me the final inch I needed.
Up front I had 5 leaf springs and I removed 3 of them. I took out the two shortest, and the 2nd longest, and left the main leaf, and the middle leaf. It gave me the ride I wanted, but front dropped down lower than I wanted at about 1.5" drop. So made up a pair of lowering blocks to go between axle and springs to raise it. The axle is over the springs, so using blocks raises it vs. the axle above the springs in the back where it lowers it with blocks.
Just have to play with it, and figure out what you'll get, and if it works. It's rarely a one try and it's good thing. Sometimes I get lucky, but often it takes a couple tries to get it right where I wanted it.

 

The bad thing about removing leaves is if you remove to many you end up like this.

That is the right front spring under the truck in my Avatar with about 3 leaves removed to do a quick and nasty lowering job that was supposed to be used for two rod runs and then be swapped for something else. The problem with removing leaves is that they keep sagging and sag a lot faster than they would otherwise.