Assuming that you keep the front stub axles regularly greased, I bet a bottle of decent Scotch that your rebound springs are under compression at static ride height, preloading the main spring and causing the front suspension to be rock hard.
Fortunately it's an easy fix, just cut the rebound springs down a bit so that the rebound springs are just clear of the stub axles when the car is sitting normally.
If you haven't been greasing the stub axles every 1000 miles or so, then it's possible the king pins have seized, especially if they are mild steel.
