On my 55 buick, whenever I go over a bump on the road the rear of the cars feels like I just dropped off a cliff or something, feels like I have no bounce back there. I have check it and everything looks good I guess.....it's got that crack headed suspension back there, not the tube shock type which in my opinon blows major donkey d#$@.
This may sound kinda hoakey Your kicker shocks/knee action shocks or whatever they are supposed to be called are probably in need of rebuilding. Instead of rebuilding mine i just bought a cheap set of airbags and stuck them in the rear coil springs. Voila!!! the car is once again smooth and rides rather comfy. Hope this helps. Rebulding the originals can be pricey if your as broke as i am. later chad