I just installed 180mm 8k/6k F/R springs on my fwd 1g with 5mm of preload. I didnít measure droop percentage. I like that It handles great, but the comfort is not there. I want to add 6k Swift tender Springs to the front . I canít find any example of someone doing this.
with the 8k (450lbs) spring in tandem the Initial rate would be 192lbs with a 6k spring for the first 72mm before coil bind.
if the corner sprung weight is about 800lbs:
8k spring will depress 45.7mm and the 6k spring will depress 57.14mm
Necessary preload would be approximately 53mm to retain 50mm of droop travel. So after accounting for that I end up with about 15mm of travel as dual rate before going to the full 8k rate again. This is just an estimate and I didnít measure anything yet. Is this worth the cost and effort? Did I even figure this out right? Would a 7k main spring be a better course of correction? When I get a chance I will make some measurements.
Edit: Measuring droop in front I found 38mm driver side 29mm passenger side. It seems the sprung weight is a little less than 800lbs a corner. Itís about 665lbs DS, 507lbs PS. 731/557 with motion ratio calculated.