I'm planning on cutting the springs on my '70 sportsroof this weekend. I have the 620 1" lowered springs and plan on cutting approx. 1/2 coil to drop the front an additional 1".
I believe that I've read that cutting the springs will affect the rate and stiffen the suspension. If it's not too extreme then it's no problem, I prefer a stiff ride as long as it's not bone shattering.
Also, with cutting already shorter springs is there any worry about them being too short in terms of proper seating between the control arms?
I personally would not cut those springs. You will gain quite a bit if stiffness and you will be further from proper ride height. for best handling the pivot for the LCA and the pivot on the ball joint should be the same distance to the ground "proper ride height". the shorter the springs the more the inner pivot will be lower then the outer pivot. If you cut them any way I would only do it 1/4 at a time a give the front end a month or two to settle before cutting it again, and if the springs on the car now are new, weight at least a month to cut them.
I have a 67 vert, with 620's, I cut 2/3 a coil off with my shelby drop and konis, the ride was fine. I changed to GW UCA's and roller perches and had to cout another 1/3 a coil to get the drop I had before and it rides nicer than it did before. On a 70 the wieght is more like my vert, I do have a 408 stroker but with alum heads and int. Maybe with a lighter wieght eng it may ride slightly stiffer but I cant see it being too stiff.
I run my konis on 2/3 stiff, have an 1 1/8 sway bar and it rides very nice, its very smooth, its like a slightly firm yet contolled ride much better than stock in my opinion
