| Proper tools and the maximum possible care and cleanliness are essential for satisfactory repairs to the transmission units. The usual basic safety precautions also naturally apply when carrying out repair work. |
| To avoid unnecessary repetition, a number of generally applicable instructions for the various repair procedures are summarised here. They apply to the work described in this Manual. |
| Guided Fault Finding, Vehicle Self-Diagnosis and Test Instruments |
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| Before servicing the gearbox, the cause of the fault should be identified as exactly as possible using the vehicle diagnostic tester via Guided Fault Finding, Vehicle Self-diagnosis and Test Instruments. |
| Environmental and waste disposal regulations for oil |
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| ATF, gear oil (MTF) and any other type of oil must be handled with care. |
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| Dispose of drained oil properly. |
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| ATF or gear oil (MTF) that has been drained off must not be used for refilling the gearbox. |
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| Always adhere to statutory environmental and waste disposal regulations. |
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| Observe the information shown on the packaging of the oil. |
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| Rules for cleanliness when working on the dual clutch gearbox → Chapter. |
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| Do not run the engine or tow the vehicle with the ATF oil pan removed or when there is no gear oil (MTF) in the gearbox. |
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| When installing gearbox, ensure that dowel sleeves are fitted correctly. |
| O-rings, oil seals and gaskets |
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| Rules for cleanliness when working on the dual clutch gearbox → Chapter. |
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| Always renew O-rings, oil seals and gaskets. |
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| After removing gaskets and seals, always inspect the contact surface on the housing or shaft for burrs resulting from removal or for other signs of damage. |
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| Thoroughly clean housing joint surfaces before assembling. |
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| Before installing, lightly lubricate outer circumference and sealing lips of oil seals with ATF or gear oil (MTF), depending on fitting location. |
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| Lightly lubricate O-rings with ATF before installation to prevent them from being crushed during assembly. |
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| Use only ATF for parts running in ATF. Other lubricants will cause malfunction of the gearbox hydraulics. |
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| The open side of the oil seal should face the side containing the fluid. |
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| Slacken bolts in reverse sequence to the specified tightening sequence. |
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| Bolts and nuts used to secure covers and housings must be tightened in steps according to the specified tightening sequence and method. |
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| Nuts and bolts which secure covers and housings should be loosened and tightened in diagonal sequence and in stages if no tightening sequence is specified. |
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| Always renew self-locking bolts and nuts. |
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| Use a wire brush to clean the threads of bolts which are secured with locking fluid. Then install bolts with locking fluid; for locking fluid refer to → Electronic parts catalogue. |
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| Threaded holes which take self-locking bolts or bolts coated with locking fluid must be cleaned (using a tap or similar). Otherwise there is a danger of the bolts shearing off the next time they are removed. |
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| The tightening torques stated apply to non-oiled nuts and bolts. |
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| Do not over-stretch circlips. |
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| Renew circlips which have been damaged or over-tensioned. |
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| Circlips must be properly seated in the base of the groove. |
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| Install needle bearings so the lettering (side with thicker metal) faces towards the installing tool. |
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| Lubricate bearings with gear oil (MTF) or ATF, depending on fitting location. |
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| Do not interchange inner or outer races of bearings of the same size. |
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| Always renew the tapered roller bearings on one shaft together and use new bearings from a single manufacturer. |
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| Use a micrometer to measure the shims at several points. Different shim thicknesses make it possible to obtain the exact shim thickness required; if necessary, fit 2 shims. |
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| Check for burrs and damage. Install only shims which are in perfect condition. |
Caution | The gearbox control unit (mechatronic unit) can be damaged by electrostatic discharge. |
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| Before handling the electrical connector or mechatronic unit, the mechanic must discharge static by briefly touching an earthed metal object, such as vehicle earth, lifting platform or heater radiator, etc. |
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| Do not touch contact pins in gearbox connector with bare hands. |
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