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new clutch technology to the DTM

Sachs introduces new clutch technology to the DTM: 25 percent lighter and more user friendly


„The clutch is very important in the DTM“, knows Christian Abt, one of the six drivers, who‘s Audi A4 DTM is equipped with hightech clutches from ZF Sachs Race Enginering. „Only those who get off the line well at the start and after pit stops have a chance of winning”, explained Christian Abt.

As in a normal car, pulling away with the DTM racer is a balancing act between the clutch and throttle pedal feet. Only the pedal travel is considerably shorter. The foot must simultaneously exert more pressure without losing‘feel‘. Because, instead of the centimetres moved in a streetcar, the pedals in the Audi A4 DTM must only be depressed a few millimetres to allow the car to shoot forward – or stall. „The psychological pressure on the driver when pulling away is tremendous”, described seasoned racer Christian Abt. „We are aware of the problems”, mentioned Thomas Rudolf, Sachs Race Engineering clutch expert. „That‘s why smooth clutch reengagement characteristics were of a very high priority during the development of the new DTM clutch, which is, incidentally, very closely related to the World Rally Championship version.”

The team from Schweinfurt achieved this goal thanks to the superior elasticity of the spring element. Christian Abt confirmed: „The predecessor of the 2003 clutch was already excellent, the new model is even easier to use.” The high-tech component can be adjusted individually to suit each driver. However, the new version of the GMFZ 3/140 Y clutch -,3‘ indicates the number of clutch plates,,140‘ the plate diameter in millimetres and‘Y‘ for the carbon plate material – is not only more user friendly, but has lost a quarter of its original weight and now weighs a mere 3000 grams. As a comparison: In a production car, the‘shifting aid‘ including flywheel weighs in at 22 kilos.


Such a drastic weight reduction was achieved through design stratagem. „We unceremoniously discarded the flywheel and integrated the clutch directly in the gearbox”, explained Rudolf. In addition, the Sachs engineers fitted only one of the two diaphragm springs previously responsible for the clamping forces on the carbon plate. „This reduces the mass and internal frictional losses equally”, according to Rudolf.

Obviously, such an innovative design is not delivered to the customers before all components have survived the diverse and rigorous test procedures. The new diaphragm spring is subject to a test cycle of 100,000 actuations. The carbon plates, which reach a temperature of up to 1,000 degrees during a race, must tolerate speeds of up to 15,000 revolutions per minute, which equates to almost double the maximum revs achieved in the DTM, during an endurance test.

These high quality standards distinguish Sachs components from the competition – and their partners rely on them. The partnership with Audi teams in the DTM enters its fifth year. Up to now, there was not a single clutch failure. At the same time, the heavily stressed component must survive a complete season. „We only make a visual inspection three or four times a year, compensating for the carbon plate wear by adding a corrective shim so that the diaphragm spring always has the same preload”, explained Rudolf. After this short inspection, the clutch is fit for further races – and victories.

For further information: ZF Sachs AG,
Detlef Reinhart, Director Company Communications
Phone +49 (0) 97 21 – 98 21 41, Fax +49 (0) 97 21 – 98 31 80
E-Mail: presse@sachs.de

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