How to Read A Shock Graph
-Where to start?
If you break down a shock graph, it can be very simple. At the bottom of the graph is the velocity of the shaft in (in/sec). This is in refence to inches per second, and in dirt car racing, industry norm is to dyno them at 10in/sec. Vertically along the graph is force in pounds(lbs). A positive number is compression and a negative number is rebound.
Lots of racers, for example, will state that a shock has a valving of "5-5". But those numbers are recorded at a 10in/sec, and unless the track is extremally rough, the shock never travels at that speed. So why do we rate shocks with that metric? Well its an old concept that we've kept over time, and is now obsolete. Now we refer to velocity at different in/sec, like: 1"=25# or 3"=-200 referencing the shock graph. This allows for multiple shock brands to be rated the same, by their displacement, not a number system that is in reference with a shaft velocity that the car never sees.
Graph shape is dictated by: weight of oil, temp of oil, valving, piston design, gas pressure, and bleed. All this things can be adjusted to achieve the shape wanted. Most of the time a perfect shape is impossible to achieve, but we shoot for a pound number at at certain shaft velocity and manipulate the rest of the graph to best fit the the situation.