i'm looking at getting some for a custom build...how hard was it to messure and get the right height shocks and springs?
Length is pretty easy. I have done it two ways:
1. Design suspension, build suspension.
2. Figure out mounting points.
3. Measure distance from mounting points in both bump and droop
4. Take your numbers and refer them to a shock length chart.
OR
1. Buy what you think is close
2. Move mounting points and modify suspension till they work
Spring rate is another story. With Airshocks there is no spring rate. They have no springs. What they have is an oil volume, nitrogen charge, compression and rebound shim packs and a valve.
All four of these things are adjustable and they combine to provide both the ride height and the "spring rate".
Coilovers have springs, but that is a much bigger story.