are the leaf springs different on the 4dr what I mean is is there a extra leaf cause I woul dlike replace mine on the 70 to maybe raise it up a little more.im going next weekend to check on a few parts cars a guy has thought I might do the spring swap he has a couple of early 4 drs and one 75 4dr
I used a pair of springs from a 71 4 door from a wrecking yard on my 77 2door after I had them rearched and a leaf added to give my 4. I haven't driven enough to get them to settle yet but I ended up with a 3" raise in the back. (was really to much) now shocks are short!
You cant go by the number of leafs to know the spring rate. Some 3-leaf springs were stiffer than some 4-leaf springs. You also need take note the bushings also change through the years
I put a set of leaf springs from a 74 Comet 4dr, on my 70 Grabber. I also swapped the 5 lug rearend from the same car. Now the 70 Grabber has a slight rake to it. I think it looks good. I'll be putting the front 5 lug manual disc brakes on next, from the same car.
But since you can't buy replacement springs from Ford these days, and most junk yard springs are over 35 years old, I doubt knowing spring rates, will be of much help.
