Repair Information
Repair Information
The maximum possible care and cleanliness and proper tools are essential to ensure satisfactory and successful transmission repairs. The usual basic safety precautions also, apply when carrying out vehicle repairs.
Some general repair information that applies to several procedures throughout this service information is summarized here. They apply to this repair manual.
Guided Fault Finding, Vehicle Diagnosis and Test Instruments
• Determine the cause of the malfunction as accurately as possible using guided fault finding, on board diagnostics and test instruments before starting any repairs on the transmission.
Oil, Environmental and Disposal Regulations
• Handle ATF, axle oil and other fluids with care.
• Dispose of drained ATF properly.
• Follow the legal environmental and disposal regulations.
• Follow the information provided on oil packaging.
Transmission
• Clean working conditions for the transmission => [ Clean Working Conditions ] Clean Working Conditions.
• Do not run the engine or tow the vehicle when the center differential housing is removed or when there is no ATF.
• After installing, the following fluid levels must be checked and topped off if necessary: ATF in transmission => [ ATF, Checking Level and Correcting ] ATF, Checking Level and Correcting and gear oil in transmission => [ Gear Oil in Front Final Drive, Filling after Repair ] Gear Oil In Front Final Drive, Filling After Repair.
O-rings, Shaft Seals, Seals
• O-rings, shaft seals and seals must be replaced.
• After removing gaskets, examine contact surface on housing/shaft for burr resulting from removal or for other signs of damage.
• Thoroughly clean housing joint surfaces before assembling.
• To install, thinly coat shaft seals along outer circumference and on sealing lip with ATF.
• Coat O-rings with ATF before inserting to prevent crushing rings during installation.
• Always only use approved ATF. Other types of lubrication cause faults to occur in the transmission hydraulics.
• The open side of the shaft seals point toward the fluid to be sealed in.
• Press in new shaft seal, so that the sealing lip does not run on the same point as the sealing lip of the old shaft seal (use insertion depth tolerances).
• After installing, the following fluid levels must be checked and topped off if necessary: ATF in transmission, refer to => [ ATF, Checking Level and Correcting ] ATF, Checking Level and Correcting or gear oil in transmission => [ Gear Oil in Front Final Drive, Filling after Repair ] Gear Oil In Front Final Drive, Filling After Repair.
Bolts and Nuts
• Loosen the bolts opposite the tightening sequence.
• Nuts and bolts which secure covers and housings should be tightened in steps according to the specified tightening sequence and method.
• Nuts and bolts which secure covers and housings should be loosened and tightened crosswise in stages if no tightening sequence is specified.
• Replace the self-locking nuts and bolts.
• Clean threads of bolts that were applied with locking fluid using a wire brush. Install the bolts with locking fluid (AMV 185 101 A1).
• Threaded holes into which self-locking bolts or bolts coated with locking fluid are screwed, must be cleaned (for example tap). Otherwise there is a risk that the bolts will shear the next time they are removed.
• The tightening specifications stated apply to non-oiled nuts and bolts.
Fasteners
• Do not overstretch the circlips.
• Replace damaged or stretched circlips.
• The circlips must fit completely inside the groove.
Bearings
• Install needle bearings with lettered side (thicker metal) racing the fitting tool.
• Insert bearing with axle oil or ATF, depending on installation location.
• Do not interchange the outer or inner races of bearings of the same size.
• Always replace the tapered roller bearings on one shaft together and use new bearings from a single manufacturer.
Adjusting Shims
• Measure the adjusting shims at several locations with a mircometer. Tolerance variations make it possible to find the exact shim thickness required.
• Check for burrs and damage. Only install perfect shims.