As of MY '84, the Porsche 928 S is optionally available with anti-lock system (ABS) (option M593). As of model year 1986, the 928 S is fitted with ABS as standard equipment worldwide

The anti-lock braking system represents an important contribution to the enchancement of active safety in the vehicle.

The system prevents the wheels from locking when the brakes are applied, thus assuring full steera-bility and directional stability. Furthermore, the braking distance is optimized under all road conditions.

However, it is still the responsibility of the driver to adapt his driving to road and weather conditions and to the prevailing traffic situation.

The decisive advantage offered by ABS lies in the stability and maneuverability of the vehicle in moments of danger - when the brakes are fully applied, even in a curve.

It is not possible to retrofit ABS in cars built before model year 84, as the body has undergone a number of changes since then.

Modifications, 86 models onward

As of model year 1986, the 928 S is fitted with ABS as standard equipment worldwide. At the same time, the following modifications were incorporated.

Optimization of plug-in connectors of speed sensors to cable. The cable routing has also been modified.

Number of teeth on impulse ring reduced from 90 to 45 (improved signal registration).

ABS control unit changed (adaption to impulse ring with 45 teeth). When replacing, ensure that the correct control unit is used. The only outward differences of the control units are the Part No. and Bosch part no., respectively. Observe correct usage references acc. to the spare parts catalog.

Modifications as of MY '90

Starting with MY '90, the 928 is fitted with a PSD (electronically controlled Porsche limited slip differential). For details, refer to page 45 - 08.


Acceleration and braking forces have to be transmitted to the road surface by the tires. When a free-rolling wheel is slowed down by applying the brakes, there is slip, i. e. the difference between wheel circumferential speed and vehicle speed. The wheel circumferential speed will be slower than the vehicle speed.

ABS - Operating Range

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