imo you need to raise the ride hight yes in effect putting more tension on the spring what is happenenig from what we found is the cup on top of the gaz shock top (assuming you refitted the inner cup from on top the old shockers) is pattering as you bounce on the car ie becoming loose the tight i know it sounds hard tp accept as you tension the springs up as the wheel is suspended but the shocker is dampening the effect when its on the floor ,anyways your cars to low raise it and the problem will dissappear.
best way to adjust the springs throw the c spanner in the bin and use an oil filter tool ie the big clamps to turn the seat easy as.
p.s what rears spring rates you got the standard are pants you need at least 220lbs,better not say anymore or u will be pushin me round the track pmsl
Tim