The car's travel is so short that it can bottom under cornering load alone with sticky tires. This can make cornering unpredictable with the front or rear of the car suddenly breaking away if the suspension bottoms under load. The Ground Control shocks are 1.5 inches shorter than stock so the car can be easily lowered up to 2.5 inches while still maintaining a useful amount of wheel travel. This lowers the center of gravity of the tall, boxy SE-R, further helping cornering.
When the wheel travel is maintained, you can go up in spring rate considerably while not giving up ride quality.
The other main reason we selected the Ground Control shocks is they feature digressive valving. Digressive valving is a revolutionary way of valving shocks that is entirely different than in previous shock designs. A digressive shock has stiff progressive damping at low shaft speeds, typically shaft speeds of less than 3 inches per second. This helps control body motions, such as rolling, squating, and diving, just like a typical stiff racing shock absorber.
At shaft speeds higher than this in the 3-to-10-inch-per-second velocity range, the damping force stays more or less constant, despite the rapid change in shaft velocity. This helps maintain a supple suspension response to bumps and irregularities in the pavement. This suppleness helps the car maintain traction by reducing hop in bumpy turns and gives a good ride, even at high damping rates needed for body motion control
Digressive valving is the opposite of how shocks have been traditionally valved. Usually, shocks have more damping force at higher shaft velocities than lower. This curve can be shaped and regulated to a degree by adding different valving stages. Valving stages are hydraulic fluid bypasses with check valves of differing rates and flow volumes that blow-off hydraulic fluid inside the shock at different set shaft velocities for better bump response. Even with these tricks, a conventional shock's damping curve is different than a digressive shock's curve.
Conventional shocks tend to have more damping when the shaft velocity is higher, despite multi-stage valving. Digressive shocks were first used successfully in rally and off-road racing and have only recently made their way into the on-road racing area.
The GC shocks have a general valving layout and a single tube construction much like a conventional DeCarbon-type shock such as Bilstein. A single tube shock has the advantage of better cooling and the ability to run a larger piston. A larger piston displaces more oil. Greater oil flow through the valves gives better damping control.
The piston is attached to the shock shaft and uses a flexible Swedish steel stack of thin, precision ground, shaped washers to control fluid flow. The washers cover the bleed orifices drilled into the piston for compression and rebound fluid flow.
There is a washer stack on both sides of the piston to control fluid flow going either way, in compression or rebound. The washer stacks act like one-way check valves for the fluid. As the incompressible fluid passing through the orifices in the piston hits the washers as the piston moves, they flex and bend out of the way to allow the fluid to pass.
The stack of the washers is kind of like a leaf spring, with the profile of the stack and the thickness and diameter of the washers controlling how the washer stack flexes. This controlled flex regulates how fluid passes through the orifices in the piston. That is one of the main ways Ground Control can precisely control the shape of the damping curve.
Another ingenious trick that Ground Control uses to control the shape of the damping curve is to use shock pistons with varying concaveness in the surface that the washer stack seats against that allows the washer stack to be set with differing preloads.