Technology explained: Porsche Active Suspension Management
Porsche Active Suspension Management (PASM) has been a standard feature on the 911 Carrera S since 2005. The system provides both improved grip and greater comfort – two attributes that often seem mutually exclusive.
Outwardly, a PASM damper looks almost identical to its standard sibling, save for the control wire connected to the head of the unit. It is this control wire that hints at the PASM damper’s secret.
A central control unit is connected to all four dampers on a PASM-equipped Porsche 911. When you push the PASM button, an army of sensors spring into action.
These sensors measure parameters such as steering input, body roll, and suspension bump. Alongside two accelerometers, the data is sent back to the control unit, where the PASM system determines whether to stay in ‘Normal’, or switch to ‘Sport’ mode.
In ‘Sport’ mode the dampers stiffen, allowing greater cornering performance by maintaining the tyres’ contact with the road.
In order to affect this change, inside the damper body a special bypass channel is utilised to alter the suspension’s stiffness.
All hydraulic dampers work off the same principle: the damper body is filled with oil, which is compressed by a piston. In the PASM damper, the bypass channel is used to control the flow of oil.
In ‘Normal’ mode, the valves controlling the channel are open, allowing a greater flow of oil, resulting in a softer damper. However, when ‘Sport’ mode is activated, the bypass channel is closed. This increases the compression needed to force the oil through the damper body, creating a stiffer damper, and a more responsive Porsche.