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Final drive, differential, differential lock > < Special tools

A4 Cabriolet Mk2

Components
Components
Rear final drive
t  Allocate bolts and other components according to final drive code letters, refer to → Electronic parts catalogue.
t  When installing a new rear final drive unit, check the oil level in the final drive and top up if necessary → Chapter.
t  Capacity and specification → Chapter
t  When installing mounting brackets as well as other waxed components, the contact surfaces must be cleaned. The contact surfaces must be free of wax and grease.
t  Thoroughly clean all joints and connections and the surrounding areas before dismantling.
O-rings, oil seals and gaskets
t  Always renew O-rings, seals and gaskets.
t  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.
t  Thoroughly clean housing joint surfaces before assembling.
   
t  Before installing oil seals, lightly oil the outer circumference of the seal and fill the space between the sealing lips -arrow- about half full with grease -G 052 128 A1-.
t  The open side of the oil seals faces toward the side with fluid filling.
t  Lightly lubricate O-rings before installation to prevent them from being trapped and damaged during assembly.
t  After renewing seals and gaskets, check and, if necessary, top up oil level in final drive → Chapter.
Locking elements
t  Do not over-stretch circlips.
t  Always renew circlips which have been damaged or over-stretched.
t  Circlips must be properly seated in the base of the groove.
  N32-0001
t  Renew spring pins. Position: the slit -A- should be in line with the line of force -arrow-.
Nuts, bolts
t  Nuts and bolts for securing covers and housings must be slackened and tightened in diagonal sequence.
t  Loosen and tighten particularly sensitive parts in diagonal sequence and in stages, taking care to keep them straight.
t  The tightening torques stated apply to non-oiled nuts and bolts.
t  Always renew self-locking bolts and nuts.
t  Clean the threads of bolts which are secured with locking fluid using a wire brush (does not apply to propshaft bolts: these must be renewed). Then apply locking fluid -AMV 185 101 A1- to bolt threads before installing.
t  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.
Bearings
t  Install needle bearings so the lettering (side with thicker metal) faces towards the installing tool.
t  Install new tapered roller bearings as supplied; do not lubricate additionally with oil.
t  Always renew the tapered roller bearings on one shaft together as a set and use new bearings from a single manufacturer.
t  Lubricate bearing seats lightly with gear oil before pressing bearings onto shafts.
t  Lubricate bearing seats lightly with gear oil before installing bearings and outer bearing races in final drive housing.
t  Heat inner races to approx. 100° C before installing.
t  Do not interchange the outer or inner races of bearings of the same size (the bearings are paired).
Shims
t  Use a micrometer to measure the shims at several points. Tolerance variations make it possible to obtain the exact shim thickness required.
t  Check for burrs and damage.
t  Do not install shims which are damaged or not in perfect condition.
  A34-0149

Final drive, differential, differential lock > < Special tools