Nissan Spec-V: Part 8: Installing Coil-Over Suspension
9/15/2006
Suspension is a top priority for a time attack car. Handling is more important than eking out every last bit of engine power. The key suspension component is the coil-over/shock system because it allows you to adjust spring rate, ride height and damping.
We selected KW Suspension’s race damper package. The coil-overs feature independently adjustable damping for rebound with separate adjusters for high- and low-speed compression. Low-speed compression helps reduce body roll, lift and squat. High-speed compression controls shock reactions to big bumps and holes, encountered when hopping FIA curbs or dipping a wheel off the track into a hole. The KW coil-overs are also shorter so the car can be lowered quite a bit without sacrificing wheel travel. This means our racecar has the same amount of bump travel as stock. This is important for proper handling. 
The KW shocks are high-pressure gas mono-tubes, which are generally accepted as the best for racing, with remote reservoirs. The remote reservoirs make it possible to install extra compression adjuster valves and keep the shock shorter without sacrificing wheel travel. A floating piston in the remote separates the shock oil from the 300 psi nitrogen gas. You can also adjust the gas pressure via the Schrader valve on the end of the remote. 
The front shock is an inverted shaft design, meaning the large-diameter body acts like the shock shaft as the entire shock is mounted upside-down in the strut tube. This is much stronger and more ridged than a conventional shock with a skinny shaft. One disadvantage of an inverted shaft is more friction due to the large-diameter shaft/body. KW solves this problem by using linear ball bearings in the shock housing instead of bushings. This should give a smooth, friction-free ride.
The strut mount has a lock plate to adjust the camber. Different lockplates can be selected at half-degree increments to get the camber roughly into place with no risk of slippage. By adjusting things here and on top of the shock with the camber plate, the kingpin inclination angle can be adjusted. This is an unusual adjustment and we plan on using it to our advantage.
We used Ground Control Inc., camber/caster plates as they allow adjustment of both camber and caster angles, something we deemed important for our chassis setup. The Ground Control plates have a superior design where load is taken off the spherical bearing that holds the shock shaft and placed on a roller thrust bearing. This wears a lot better and allows the top mount to articulate without friction.
The stock Spec-V strut towers are domed shaped and aren’t well suited for bolting on camber plates. We had to cut off the top of the stock shock towers and weld in the supplied mounting plate -- not a job for amateurs or the faint of heart. 
Gushy rubber is bad in a racecar, as the rubber flexes, the suspension loses its adjustment and the wheels point in wrong directions. The stock rear shock mounts are big, soft rubber donuts which soak up a lot of shock shaft movement in uncontrolled flex.KW replaced the rubber with a spherical bearing, which eliminates all flex.
The coilovers are just scratching the surface of what it takes to make an econobox handle like an exotic.