997 ELECTRONIC CENTER DIFFERENTIAL

Porsche has changed the center differential in the AWD cars from a viscous coupler to an electronic clutch-type differential.

This differential uses electromagnetic lock-up to deliver up to 100% of power to the front or rear axle. The Porsche Traction Management (PTM) computer uses input from multiple sensors (including individual wheel speed, forward and lateral acceleration and steering angle) to determine the amount of lock-up required. This adjustment takes less than 100 milliseconds.

The electromagentic center differential is simular to the Porsche-Steuer Kupplung (PSK) system used in the 964 C4, although the PSK system used high-pressure hydaulics to control clutch-pack lock-up (see below).

Porsche-Steuer Kupplung (PSK) system center differential