BestPracticeGuide_Clutch_2018

Double clutch technology

Millions of vehicles are now fitted with twin clutch systems. Are you ready?

As the “wet type” clutch rarely requires changing, it is unavailable in the aftermarket at the present time, however an extensive Euro Academy training course for the wet type double clutch systems will be available over the coming months. The “dry type” clutch requires specialist training available through Euro Car Parts/LUK and comes as an IMI certificated course, and specialist tools are also required. Both types may be used in conjunction with a dual mass flywheel. This DMF fails with the same regularity as a normal DMF, and can be easily changed by plugging both “breathers” (oil MUST NOT be lost during this procedure),and removing the gearbox. The clutch kit is pressed onto the input shaft in both cases and is not bolted to the DMF. The “wet clutch” is driven by a short, splined, stub shaft in the centre of the DMF. The “dry clutch” is driven by way of a toothed cog around the middle of the DMF. As long as the clutch is not disturbed, replacement of the DMF is relatively easy. If the clutch is removed, it MUST be replaced with a new clutch kit. If you have any problems change the oil. The pressurised oil, within the twin clutch transmission, is under immense stress, especially on units fitted with wet clutches. Most car makers insist that the oil and the external transmission filter are changed at specific intervals, typically, every 40,000 miles. A mechatronics unit operates all the dual clutch systems, this represent the ‘brain’ of the 6 and 7 speed dual-clutch gearbox. The mechatronics unit can implement complex shift operations in a fraction of a second. The main function is to open one of the clutches and to close the other at the precise moment.

Millions of vehicles are now fitted with direct shift gearbox, or direktschaltgetriebe, made popular by the Volkswagen group, their compact DSG was the first twin-clutch transmission to be released on mainstream sale from 2003. Similar systems are now available from many vehicle manufacturers, including the Fiat Group, Ford, Honda, Hyundai, Kia, Mitsubishi, Renault and Volvo. The earlier type is known as a wet type 6 speed clutch as it runs immersed in gear oil. The need to change this type of clutch will be very small as it rarely wears out. The later type is known as a dry type clutch as it resembles a traditional clutch plate assembled in a steel cartridge (as per the diagram above). Both types of gearbox operate in a similar way; having two input shafts (one solid, running down the centre of a hollow shaft). The solid shaft runs gears 1, 3, 5 and 7. The hollow shaft runs gears 2, 4, 6 and reverse. The clutch kit is running both plates and switches from one to the other in drive terms within a few milliseconds, making the gear change very smooth and swift.

If you have any questions with regard to twin plate clutch technology, training and special tools, contact your regional Technical Sales Specialist – details are on the rear cover.

16