Ian,
Not sure what year 260z you have but the '74 FSM says the spring constant is the same front and rear (1.85 mm/kg or 104 lb/in) originally. Conventionally (from speaking to some mechanically minded people) you would run a higher spring rate at the front, but its very much chassis dependent.
I am looking at spring rates myself for a GAZ setup on my 260, most people seem to be running 250 front 200 rears or a balanced setup for track use, I'll let you know if I find out anything interesting
Not sure what year 260z you have but the '74 FSM says the spring constant is the same front and rear (1.85 mm/kg or 104 lb/in) originally. Conventionally (from speaking to some mechanically minded people) you would run a higher spring rate at the front, but its very much chassis dependent.
I am looking at spring rates myself for a GAZ setup on my 260, most people seem to be running 250 front 200 rears or a balanced setup for track use, I'll let you know if I find out anything interesting