Tenneco's Kinetic Suspension, the Anti Anti-Roll Bar - Tech Dept

The lowly damper (a.k.a. shock absorber) is the unsung hero of any car’s suspension system. Ride and handling specialists sweat untold hours over them, and engineers have painstakingly improved shocks with friction-reducing seals, gas pressurization, electronic valving, and even magnetic fields. While it’s hard to argue with a 3-series BMW’s poise or the comfort strides Ferrari has achieved of late, the damper’s best days may lie ahead. Credit Australian Chris Heyring for inventing a superior means of controlling wheel and body motion and Tenneco for developing that technology into its Kinetic suspension system.

Conventional shocks use calibrated orifices restricting the oil flow through a moving piston to produce damping effects that manage some very complicated, often contradictory forces—wheel impacts (the so-called bump force) want a soft response; body heaves (roll) demand a stiffer one. The Kinetic setup keeps the piston stroking in sync with wheel motion inside an oil-filled cylinder at each corner just as in a conventional shock, but it adds some embellishments. To diminish the usual trade-offs between ride and handling, the creation and manipulation of damping forces are moved outside these hydraulic units in a manner far beyond the electronic valves and remote reservoirs employed before. A network of  hoses connects all four units to two hydraulic accumulators (sealed devices containing pressurized nitrogen and oil separated by a membrane). In the most exotic version of the Kinetic system, there’s also a pump to adjust the pressure inside the accumulators.

Heyring’s brainstorm was a scheme for interconnecting the eight chambers inside the four suspension units. The top chambers on one side of the vehicle are hydraulically linked to the opposite side’s bottom chambers, and vice versa [see schematic above].

When a one-wheel bump is encountered, the resulting suspension motion pumps oil into one chamber and out the other side of the piston at that corner of the car. To minimize the disturbance at the other corners, both accumulators regulate this flow. Damping forces are produced as the oil passes through calibrated restrictions (orifices) built into the hydraulic hose attachments.

When the car negotiates a corner, the cross-plumbing arrangement yields a response dramatically different from the one-wheel reaction. Now the outbound flow of oil from all four hydraulic units rushes into just one accumulator. The contained nitrogen acts as a spring to resist that flow. As a result, there’s no need for anti-roll bars or stiff suspension coils to keep the body from listing excessively in a bend.

Because the bump and roll modes act independently, the Kinetic system can be tuned to provide a controlled response over potholes, supple ride motions over dips, and firm resistance to body lean in sweeping bends. Adding electronically adjustable orifices allows the damping to be keyed to car velocity and the driver’s moods. Pumping extra oil into the hydraulic veins raises the accumulator pressure—and roll stiffness—to provide a handy track-day setting.