General Repair Information
General 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, naturally apply when carrying out vehicle repairs.
A number of generally applicable instructions for individual repair operations, which are otherwise mentioned at various points in this repair information, are summarized here.
Contact Corrosion
• The transmission housing and clutch housing consist of a magnesium alloy.
• Bolts and other components which come into direct contact with the transmission have a surface coating adapted for this.
• Contact corrosion occurs when incorrect components (bolts, nuts, washers, etc.) are used. The transmission housing and clutch housing are damaged.
Transmission
• When installing the transmission, make sure that the alignment sleeves between the engine and transmission are positioned correctly.
• Clean contact surfaces when repairing mounting brackets and waxed components. Contact surfaces must be free of grease and wax.
• After installing, check the transmission fluid. Refer to => [ Transmission Fluid, Checking ] Service and Repair.
Gaskets and Seals
• Thoroughly clean the separation surfaces and apply sealing paste (AMV 188 200 03).
• Apply the sealant uniformly, but not too thick.
• Replace gaskets and oil seals.
• After removing gaskets, examine the contact surface on the housing/shaft for burrs resulting from removal or for other signs of damage.
• Before installing radial shaft seals, lightly lubricate the outer circumference and fill the space between the sealing lips halfway with sealing grease (G 052 128 A1) - arrow -.
• The open side of the seal points toward the fluid to be sealed in.
• After installing, check the transmission fluid. Refer to => [ Transmission Fluid, Checking ] Service and Repair.
• Lightly lubricate the O-rings before installing to prevent them from being crushed when inserting.
Sealant
• Always thoroughly clean the separating surfaces on the housing before applying the sealant.
• Apply the sealing compound (AMV 188 200 03) evenly and not too thick.
• Do not allow the sealing compound to enter ventilation openings.
Fasteners
• Replace the circlip.
• Do not stretch the circlips.
• Circlips must locate properly in the groove.
• Replace spring pins. Installed position: slot is longitudinal to line of force.
Bolts and Nuts
• Always loosen or tighten bolts and nuts for covers and housings diagonally.
• Especially delicate parts - for example, clutch pressure plates - must not be distorted and must be loosened and tightened in stages in a diagonal sequence.
• The tightening specifications stated apply to non-lubricated nuts and bolts.
• Replace self locking bolts and nuts.
• Ensure with bolted connections that the contact surfaces as well as the visible surfaces of the nuts and bolts are waxed after assembly, if necessary.
• All threaded holes in which self locking bolts are threaded must be cleaned of remaining locking fluid using a tap. Otherwise there is a risk that the bolts will shear the next time they are removed.
Bearings
• Install new tapered roller bearing as supplied and do not use additional oil.
• Install needle bearings with the lettered side (thicker metal) towards the installation tool.
• Tapered roller bearings fitted to one shaft must be replaced as a set. Use the same make of bearings.
• Heat the tapered roller bearing inner races to approximately 100 °C (212 °F) with the heat gun (VAS 6414) before installing. Press on until seated when installing, so there is no axial clearance.
• Do not interchange inner and outer bearing races with those from other bearings of the same size, bearings are paired.
Adjusting Shims
• Measure shims at several points using a micrometer. Tolerance variations make it possible to find the exact shim thickness required.
• Check for burrs and damage.
• Only install perfect shims.
Synchronizer Rings
• Do not interchange. When reusing synchronizer rings, always install to the same gear wheel.
• Check for wear and replace if necessary.
• Check the grooves - arrow 1 - of the synchronizer ring - A - and inner race for flat areas (grooves are worn).
• For coated synchronizer rings, coating must not be damaged.
• If an intermediate ring - B - is installed, check the intermediate ring on the outer contact surface - arrow 2 - and inner contact surface - arrow 3 - for grooves, scoring and blue coloring (from overheating).
• Check taper of drive gear for grooves and scoring.
• Coat the synchronization with gear oil before installing.
Gears
• Before pressing on, clean and warm to 100 °C (212 °F) Max. with the heat gun (VAS 6414).
Selector Gears
• After assembly, check the selector gears for a minimum axial clearance and ease of movement.
Clutch
• Do not distort the clutch pressure plate; loosen and tighten in a diagonal sequence and in gradual stages.
• To reduce odor caused by a burnt clutch, thoroughly clean the clutch housing and the flywheel running surface with a clean cloth.