Does anyone know when changing shackle length to adjust rear ride height, is it as simple as changing shackle length say one inch, to move ride height one inch? (ie 2 inches to change 2 inches)... Thoughts?

Thanks!

 

Yes, it is this simple. Spring arch never changes.

 

Great, Thanks for that insight!

 

In the next month or so I will probably get to this. I will post my results.

 

To answer your question, no it's not that simple. Lowering the rear of the leaf spring one inch by use of a longer shackle will raise the rear body about half that amount, because the axle is at the center of the leaf spring pivot point (spring eye to eye).
If you were to lower both the rear and front leaf spring mounting points an inch, then that would equal an inch of rear body rise.

 

If you use a longer shackle to raise the back of your car .It will also raise the center of gravity and lose handling as well.