Quote Originally Posted by pballance View Post
If I were in your shoes, and could use 4 springs of equal length and get the car set, that is what I would do. Otherwise SHUT UP AND DRIVE! didn't we have that conversation?
That.

The natural frequency of the suspension springs for the rates and dimensions commonly used on 240Z's is inconsequential. Now you want to talk about spring harmonics when it comes to valve springs on and L24 and we have something worth discussing. We always used 10" free length springs on cars I prepped because I didn't have to worry about stack up for any reasonable rates, and it put the spring perches in convenient places relative to the strut tube to not cause any issues or clearance problems.

We won a ton of races back in the day with rates under 250 on both ends. Big springs, remember, are going to require more consistency and precision on the part of the driver, and may not be as much fun to drive, or drive well, depending on how regular your track days are.