Rear Final Drive: Other Audi S8 D3 facelift

Contact corrosion

Contact corrosion can occur if non-approved fasteners (bolts, nuts, washers), rivets, plugs, grommets or adhesives are used on the vehicle.

For this reason the manufacturer installs only fasteners with a special surface coating (Dachromet). These parts can be identified by their greenish color.

Rubber, plastic and adhesives also consist of non-conductive materials.

These approved parts are compatible with aluminum. They are also sold as spare parts.

If you are not sure whether used parts can be re-installed, always use new parts.

General repair instructions

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 performing vehicle repairs.

A number of generally applicable instructions for individual repair operations, which are otherwise mentioned at various points in the article, are summarized here. They apply to this article.

Car jack mode

Activate the car jack mode before lifting the vehicle on a hoist (i.e. when there is no weight on the wheels)

Refer to 43 - SELF LEVELING SUSPENSION ; Operating air suspension; Car jack mode

Special tools

Summaries of the special tools used in this article can be found at the beginning of most of the repair procedures

Final drive unit

1. When installing a new rear final drive, check oil level in rear final drive and top off if necessary. Refer to «Rear final drive oil level, checking»(ref-289216-S01691871072008062700000) .
2. Capacities and specifications. Refer to «Code letters, ratios, capacities»(ref-289216-S01611146742008062700000) .
3. When assembling mounting brackets as well as other waxed components the contact surfaces must be cleaned. Mating surfaces must be free of grease and wax.

Gaskets, sealing rings

1. Replace "O-rings".
2. Radial shaft oil seals.

Before installing

Scheme 61

Lightly oil outer edge and half-fill space between sealing lips (arrow) with grease G 052 128 A1.

After installation

Check rear final drive oil level; if necessary top-up to lower edge of oil filler hole. Specification. Refer to Code letters, ratios, capacities .

Locking devices

1. Replace circlips.
2. Do not overstretch circlips.
3. Circlips must locate properly in the groove.

Scheme 62

1. Replace spring pins. Installation position: slot longitudinal to line of force.

Bolts and nuts

1. Tighten and loosen bolts and nuts for securing covers and housings in a diagonal sequence.
2. Especially delicate parts must not be canted when removing or installing. Loosen and tighten in stages in a diagonal sequence.
3. Tightening torques as specified are for unoiled bolts and nuts.
4. Replace self-locking bolts and nuts.

1. Rewax all visible surfaces of nuts/bolts and screws of all bolted connections after installing, if necessary.

Bearings

1. Install needle bearings with lettered side (thicker metal) toward installation tool.
2. Install new tapered roller bearings as delivered and do not apply additional lubrication.
3. Tapered roller bearings installed to one shaft must be replaced as a set. Use same make of bearings.
4. Heat inner races to approx. 100° C before installing.

1. Do not interchange outer or inner races of bearings of the same size. The bearings are matched in pairs.

Shims

1. Measure shims at several points with a micrometer. Tolerance variations make it possible to find the exact shim thickness required.
2. Check for burrs and damage.
3. Only install perfect shims.

Driveshaft, servicing

Note. Refer to General repair instructions. Refer to General repair instructions . Activate the car jack mode before lifting the vehicle on a hoist (i.e. when there is no weight on the wheels)

Refer to 43 - SELF LEVELING SUSPENSION ; Operating air suspension; Car jack mode

1. The driveshaft can be bent as far as the end stop of the center joint provided that no force is used. Bending the joint forcibly to the end stop can damage the center joint.
2. Always store and transport the driveshaft in the extended position.
3. No repair work can be performed on the driveshaft with the exception of removing, installing and adjusting.
4. If the driveshaft is only disconnected at one end (i.e. from the transmission or from the rear final drive) it must be tied up at the constant velocity joints.

1. Before removing, mark the positions of all parts in relation to each other. Re-install in the same position or imbalance will be excessive and the bearings could be damaged and cause rumbling noises.
2. When the driveshaft has been disconnected from the rear final drive, the balance disc (thick washer) that may be installed between the lock plate and the socket head bolt must not be re-installed.
3. If the customer reports a droning noise or vibrations, always start by checking the radial run-out at the driveshaft flange on the rear final drive before replacing the driveshaft. Accurate adjustment may correct the fault. Refer to «Measuring and marking radial run-out at driveshaft flange on rear final drive»(ref-289216-S17147693012008062700000) .

Scheme 63

1 - Rear final drive

2 - Gasket

1. Replace
2. Pull off backing foil, and stick self-adhesive side of gasket to flange shaft.

3 - Driveshaft

1. Removing and installing. Refer to «Driveshaft, removing and installing»(ref-289216-S04598571542008062700000)
2. Remove grease from flange shaft

4 - Balance disc

1. Not installed on all vehicles
2. Location: at rear final drive between one socket head bolt -5- and lock plate -6-.
3. If installed, balance disc must not be re-installed when driveshaft has been disconnected from rear final drive.

5 - Hex socket head bolt - 55 Nm

1. Self-locking
2. Replace
3. Bolt threads in flange shafts must always be cleaned (e.g. with a thread tap)

6 - Lock plate

7 - Center bearing

8 - Combi bolt - 23 Nm

9 - Transmission

Driveshaft, removing and installing

Special tools, testers and auxiliary items

Scheme 64

1. Assembly appliance 3139

Scheme 65

1. Spacers 3139/3

Removing

1. Observe notes. Refer to «Driveshaft, servicing»(ref-289216-S01953071222008062700000)

1. Disconnect both tunnel struts -A- and -B-.
2. Remove rear section of exhaust system -C- (rearward of exhaust pipe clamp(s))

Refer to 26 - EXHAUST SYSTEM, EMISSION CONTROLS for 4.2 LITER V8 4V ENGINE MECHANICAL, ENGINE CODE(S): BVJ or 26 - EXHAUST SYSTEM, EMISSION CONTROLS for 4.2 LITER V8 5V ENGINE MECHANICAL, ENGINE CODE(S): BFM ; Removing and installing exhaust system

1. Unbolt heat shield -D- for center bearing.

Scheme 66

1. Remove bolts (arrows -A- and -B-) and take off cover.

Note. Avoid excessive bending of the flexible pipe connection (decoupling element) on the front exhaust pipe. The angle between the front muffler and the front exhaust pipe must not exceed 10° or the flexible connection will be damaged.

Scheme 67

1. Remove nuts securing front mufflers (arrows) and tie up or support front mufflers.

Scheme 68

1. Remove bolts (arrows) and remove heat shield -A- from transmission.

Scheme 69

1. Check whether there is a factory marking (paint) on driveshaft and driveshaft/rear final drive flange. If not, mark position of driveshaft flange (arrow -A-) in relation to rear final drive (arrow -B-) with paint.

Scheme 70

1. Thread bolt -3- (M10 x 100) into rear final drive.
2. Counterhold driveshaft using a suitable lever -2- and loosen bolts -1- at front and rear.
3. Unscrew three upper securing bolts on each driveshaft constant velocity joint.

Scheme 71

1. Attach assembly appliance and tighten plastic nuts.

Note. Never install assembly appliance onto balance plates.

1. Remove three remaining bolts from front and rear constant velocity joints.
2. Push back constant velocity joints on driveshaft as far as they will go.
3. Unscrew securing bolts for center bearing and remove driveshaft together with assembly appliance.

Note. Always transport and store the driveshaft in the extended position.

Installing

Install in reverse sequence; note the following points

Note. To prevent imbalance, the flanges on the driveshaft (arrow -A-) and on the rear final drive (arrow -B-) must be installed so that the factory markings (or the markings made on removal) are in alignment. If a new driveshaft is being installed and the factory marking on the rear final drive flange is no longer visible, the radial run-out at the flange on the rear final drive must be measured. Refer to Measuring and marking radial run-out at driveshaft flange on rear final drive , and the paint marking on the driveshaft must be aligned with the new marking on the flange. Replace gaskets on flange shafts (pull off backing foil and stick gasket onto flange). Remove old, dried-out high-temperature grease from constant velocity joints and driveshaft flanges. Put in exactly the same quantity of fresh high-temperature grease G 000 633. After removing the driveshaft from the rear final drive, the balance disc (thick washer) that may be installed between the lock plate and the socket head bolt must not be re-installed. After removing the driveshaft, it is important to clean any remaining locking compound out of the threads in the flange shafts on the driveshaft and rear final drive. If this is not done the new bolts can seize when they are threaded in and shear off later if they have to be removed. The threaded holes can be cleaned with a thread tap. Replace driveshaft bolts (self-locking).

1. Install driveshaft and install bolts for constant velocity joints.

Scheme 72

1. Thread in securing bolts (arrows) for center bearing hand-tight.

1. Thread bolt -3- (M10 x 100) into rear final drive.
2. Counterhold driveshaft using a suitable lever -2- and tighten bolts -1- at front and rear.
3. Remove assembly appliance 3139.

Aligning center bearing

1. Slightly loosen securing bolts for center bearing.

Scheme 73

1. Slide driveshaft forward as far as it will go and mark position of center bearing on body (arrow -A-).
2. Slide driveshaft to rear as far as it will go and mark position of center bearing on body (arrow -B-).
3. Push driveshaft to right as far as it will go and mark position of center bearing on body (arrow -1-).
4. Push driveshaft to left as far as it will go and mark position of center bearing on body (arrow -2-).

1. Align driveshaft centrally (arrow -C- and arrow -3-).

1. Center bearing must be positioned centrally between markings -A- and -B- and markings -1- and -2

1. Tighten center bearing securing bolts.
2. Install heat shield above center bearing.
3. Install exhaust system and align so it is free of stress

Refer to 26 - EXHAUST SYSTEM, EMISSION CONTROLS for 4.2 LITER V8 4V ENGINE MECHANICAL, ENGINE CODE(S): BVJ or 26 - EXHAUST SYSTEM, EMISSION CONTROLS for 4.2 LITER V8 5V ENGINE MECHANICAL, ENGINE CODE(S): BFM ; Removing and installing exhaust system

Differential, removing and installing

Note. General repair instructions. Refer to General repair instructions . Adjustments are required when replacing components marked 1). Refer to --> Adjustment overview .

Clamping rear final drive in engine/transmission support. Refer to Rear final drive, securing to engine/transmission support

1 - Breather sleeve

1. With rubber valve
2. Installation position. see scheme 81

2 - Final drive housing 1)

1. Removing and installing drive pinion. Refer to «Drive pinion, removing, installing, disassembling and assembling»(ref-289216-S33730261542008062700000)

3 - Outer race for large tapered roller bearing 1)

1. Removing and installing. Refer to «Differential, disassembling and assembling»(ref-289216-S07177048242008062700000)

4 - Shim "S1"

1. Note thickness
2. Adjustment overview. Refer to «Adjustment overview»(ref-289216-S09727709592008062700000)

5 - Cover for final drive 1)

1. With O-ring
2. Replace O-ring
3. Lubricate O-ring with oil when installing

6 - Torx bolt - 25 Nm

7 - Oil seal, right

1. Replacing. Refer to «Flange shaft oil seals, replacing»(ref-289216-S21672841602008062700000)

8 - Hex socket head bolt - 25 Nm

9 - Flange shaft, right

1. Removing and installing. (Scheme 77)

10 - Oil filler plug - 35 Nm

1. Checking rear final drive oil level. Refer to «Rear final drive oil level, checking»(ref-289216-S01691871072008062700000)

11 - Differential with ring gear 1)

1. Disassembling and assembling. Refer to «Differential, disassembling and assembling»(ref-289216-S07177048242008062700000)

12 - Oil drain plug - 35 Nm

13 - Bushing

1. Holds magnet in position

1. Knock-in onto stop

14 - Magnet

15 - Outer race for small tapered roller bearing 1)

1. Removing and installing. Refer to «Differential, disassembling and assembling»(ref-289216-S07177048242008062700000)

16 - Shim "S2"

1. Note thickness
2. Adjustment overview. Refer to «Adjustment overview»(ref-289216-S09727709592008062700000)

17 - Oil seal, left

1. Replacing. Refer to «Flange shaft oil seals, replacing»(ref-289216-S21672841602008062700000)

18 - Flange shaft, left

1. Removing and installing. (Scheme 77)

19 - Hex socket head bolt - 25 Nm

20 - Cover

1. Installing. see scheme 80

Scheme 74

Scheme 75

Scheme 76

Scheme 77

The breather sleeve should project 13 mm (distance "a") out of the housing after pressing in.

The slot in the rubber valve should be in line with the direction of travel.

1. Rear final drive removed

Special tools, testers and auxiliary items

1. Drip tray V.A.G 1306

1. Secure complete rear final drive on engine/transmission support VW 540. Refer to «Rear final drive, securing to engine/transmission support»(ref-289216-S10817510752008062700000) .
2. Place drip tray underneath to collect oil.
3. Drain gear oil.

1. Remove left and right-hand flange shafts.

1. Loosen securing bolt by threading two bolts into flange shaft and counter-holding with a lever.
2. Mark flange shafts (left and right) and pull out.
3. Unscrew securing bolts from cover for final drive.
4. Remove cover for final drive from axle housing and remove differential.

Install in reverse order.

1. Insert differential.
2. Replace final drive cover O-ring and oil before installing.
3. Install cover for final drive on final drive housing and tighten in diagonal sequence to 25 Nm.
4. Fill space between sealing lip and dust lip with a thin coating of sealing grease G052 128 A1.

1. Install flange shafts and tighten to 25 Nm.
2. Top off gear oil in rear final drive and check oil level. Refer to «Rear final drive oil level, checking»(ref-289216-S01691871072008062700000) .

Pulling flange for driveshaft off drive pinion

1. Thread two M8 x 30 hex bolts -A- into flange.

Scheme 78

Scheme 79

A- = Counter support e.g. Kukko 22/2

B- = Internal puller 46... 58 mm, e.g. Kukko 21/7

Scheme 80

1. After removing check shims for damage.

Scheme 81

A - = Separating device 22... 115 mm, e.g. Kukko 17/2

Scheme 82

1. Heat bearing to approx. 100° C, place in position and press home.

Scheme 83

1. Lightly oil bearing seat in housing.
2. Insert shim "S3" appropriate for drive pinion. Refer to «Adjustment overview»(ref-289216-S09727709592008062700000) .

The identification "oben" (top) on thrust washer 3253/4 faces nut of puller.

Scheme 84

1. Lightly oil bearing seat in housing.
2. Insert outer race starting with drift VW 295 and thrust plate 30-205.

Scheme 85

1. Insert drive pinion with new spacer sleeve.

1. Heat inner race for small tapered roller bearing to approx. 100° C and place onto drive pinion.
2. Press up drive pinion and insert bearing with thrust plate 40-21 onto stop.

Installing O-ring

1. Lubricate O-ring with transmission oil and install.

Driving in oil seal for flange for driveshaft

1. Lightly oil outer circumference of seal.
2. Drive in seal onto stop with drift 3026.
3. Half fill volume between sealing lip and dust lip with sealing grease G 052 128 A1.

Installing flange

1. Drive flange for driveshaft onto drive pinion until nut can be installed.

Securing drive pinion nut

1. After securing nut, measure radial run-out at flange for driveshaft. Refer to «Measuring and marking radial run-out at driveshaft flange on rear final drive»(ref-289216-S17147693012008062700000) .

General notes

1. Careful adjustment of the drive pinion and ring gear is important for the service life and smooth running of the final drive. For this reason, the drive pinion and ring gear are matched together during manufacture, and checked to ensure a good mesh pattern and quiet running in both directions of rotation. The position of quietest running is found by moving the drive pinion in an axial direction and at the same time lifting the ring gear out of the zero-play mesh position by the amount necessary to maintain the backlash within the specified tolerance.
2. The object of this adjustment is to reproduce the setting for the quietest possible running as obtained on the test machine in production.
3. The deviation (or tolerance) "r", which is related to the master gauge "Ro" is measured for the final drive sets supplied as replacement parts and marked on the outer circumference of the ring gear. The final drive set (drive pinion and ring gear) may only be replaced together as a matched pair.
4. Observe the general repair instructions for tapered roller bearings and shims.

1. Maximum care and cleanliness are essential for achieving good results when performing repairs and taking measurements.

Scheme 86

1 - Identification "0937" signifies Oerlikon gear set with a ratio of 37:9.

Note. Klingelnberg gear set "K937" or Gleasen gear set "G937" could also be installed.

2 - Gear set pairing number (312).

3 - Deviation (tolerance) "r" is based on the test machine master gauge used in the production. The deviation "r" is always given in 1/100 mm. Example: "25" signifies r = 0.25 mm

Ro - Length of master gauge used for test machine "Ro".

Ro - Ring gear = 57.50 mm

R - Actual distance between center axis of ring gear and face of drive pinion at point with quietest running for this gear set. R = Ro + r

Vo - Hypoid offset

Scheme 87

Note. Adjustment overview when replacing individual components of final drive. Refer to Adjustment overview .

S1 - Adjustment shim for ring gear in cover for final drive

S2 - Adjustment shim for ring gear in final drive housing

S3 - Adjustment shim for drive pinion in final drive housing

Recommended sequence for readjusting final drive set

The following work sequence is recommended to save time when the drive pinion and ring gear have to be adjusted

Note. Overview of components and shims. Refer to Position of shims .

Drive pinion, adjusting

Special tools and workshop equipment required

Scheme 88

1. VW 385 Universal mandrel

1. VW 540 Engine and transmission holder

Note. Before adjusting drive pinion, adjust ring gear (determine total shim thickness "Stotal" for shims "S1" + "S2"). Refer to Ring gear, adjusting . The drive pinion only has to be readjusted if the final drive set (ring gear and drive pinion), the tapered roller bearings for the drive pinion or the final drive housing are replaced. Adjustment overview. Refer to Adjustment overview . Do not additionally oil new tapered roller bearings for frictional torque measurement. The bearings have already been treated with a special oil by the manufacturer.

Determine thickness of shim "S3"

(Setting preload of tapered roller bearing for drive pinion)

1. Mount final drive on engine/transmission support. Refer to «Rear final drive, securing to engine/transmission support»(ref-289216-S10817510752008062700000).
2. Insert both tapered roller bearing outer races without shims into housing. see scheme 115and see scheme 116.

1. Insert drive pinion without spacer sleeve.
2. Heat inner race for tapered roller bearing to approx. 100° C and fit onto drive pinion.

Note. Only install spacer sleeve for final frictional torque measurement (after determining shim "S3"). Install new tapered roller bearings as supplied and do not oil additionally.

1. Install driveshaft flange and tighten hex nut for flange. Refer to «Installing flange»(ref-289216-S14966714452009020500000) .

A- = Torque gauge, commercially available, 0 to 600 Ncm

B- = Socket attachment, 36 mm A/F

1. Tighten drive pinion nut until following friction torque is obtained.

1) run at least 50 km (30 miles)

Scheme 89

1. Set adjustment ring of universal mandrel VW 385/1.

1. Distance a = 60 mm

1. Set sliding adjustment ring.

1. Dimension b = 55 mm

Scheme 90

1. Assemble universal mandrel as illustrated

1. Dial gauge extension VW 385/15 = 9 mm long

1. Set universal master gauge VW 385/30.

1. Ro = 57.50 mm

1. Set dial gauge (3 mm measuring range) to "0" with 2 mm preload.
2. Turn drive pinion at least 8 turns in both directions so that tapered roller bearings settle.

Scheme 91

1. Place end measuring plate VW 385/33 onto drive pinion head.

Scheme 92

1. Remove master gauge and insert measuring mandrel in housing.

1. The centering disc VW 385/3 faces toward cover for final drive

1. Install cover for final drive and tighten 4 bolts.
2. Using adjustable ring, move 2nd centering disc out as far as possible so that mandrel can still just be turned by hand.

Determining measurement "e"

Scheme 93

1. Turn mandrel until dial gauge point touches end measuring plate on drive pinion head, then measure maximum deflection (return point). Measured value is dimension "e" (in red scale).

1. Measurement in following example: "e" = 1.60 mm

Note. Dimension "e" is required to determine thickness of shim "S3".

1. After removing universal mandrel, check once again whether dial gauge reads "0" with 2 mm preload when master gauge VW 385/30 is in place - otherwise repeat measurement.

Determining shim thickness "S3"

1. Determine shim(s) as accurately as possible from table. Part numbers

The following shims are available for "S3"

1) Using the shim tolerance variations it is possible to find the exact shim thickness required. Insert two shims if necessary.

1. Remove universal mandrel.
2. Remove drive pinion and outer race of large tapered roller bearing and install together with measured shims "S3" and spacer sleeve. Refer to --> «Removing nut for drive pinion»(ref-289216-S27721287392009020500000).
3. Insert small tapered roller bearing inner race and tighten nut for drive pinion until specified friction torque is obtained. (Scheme 88)

Note. Do not additionally oil new tapered roller bearings for frictional torque measurement. The bearings have already been treated with a special oil by the manufacturer. Increase tightening torque slowly and check friction torque at regular intervals. If the specified friction torque is exceeded the spacer sleeve must be replaced and the adjustment repeated. A spacer sleeve which has been compressed too much cannot be reused.

1. Set to following frictional torques

1) run at least 50 km (30 miles)

Performing check measurement

Checking dimension "r"

1. Turn drive pinion 8 turns in both directions so that tapered roller bearings settle.

1. Insert universal mandrel and perform check measurement.

1. If the correct shims have been selected, the dial gauge should now show the value of "r" as marked on the ring gear, reading counter-clockwise in the red scale, within a tolerance of ± 0.05 mm.

1. Peen drive pinion nut with a punch.
2. Measure and mark radial run-out at flange for driveshaft. Refer to «Measuring and marking radial run-out at driveshaft flange on rear final drive»(ref-289216-S17147693012008062700000) .

Ring gear, adjusting

(Adjusting differential)

Special tools and equipment required

Scheme 94

1. VW 385/17 End measuring plate
2. VW 387 Universal dial gauge bracket
3. VW 388 Adjustable measuring lever
4. VW 521 Ring gear adjusting device

1. V.A.G 1331 Torque wrench or equivalent

It is necessary to readjust the ring gear when

Rear axle housing

Final drive cover

Differential tapered roller bearings

Differential housing or

Drive pinion set

are replaced.

Adjustment overview. Refer to Adjustment overview

Note. Differential tapered roller bearings are low-friction bearings. Therefore the frictional torque only has a limited use as a check. Correct adjustment is only possible by determining the total shim thickness "Stotal". Do not additionally oil new tapered roller bearings for frictional torque measurement. The bearings have already been treated with a special oil by the manufacturer.

Determining total shim thickness "Stotal" for shims "S1" + "S2"

(Setting preload of tapered roller bearing for differential)

1. Drive pinion removed!

Note. When the tapered roller bearing for the differential requires replacing the ring gear can be removed from the differential housing. The drive pinion need not be removed.

1. Pull out flange shaft oil seal with lever.
2. Remove differential tapered roller bearing outer races and take out shims. Refer to «Differential, disassembling and assembling»(ref-289216-S07177048242008062700000) .
3. Press outer race of left-hand tapered roller bearing for differential (housing side) with shim "S2*" (1.00 mm thick) into housing. Refer to «Differential, disassembling and assembling»(ref-289216-S07177048242008062700000) .

Note. For measurement purposes a shim "S2" of 1.00 mm is initially inserted which will be designated "S2*" in the following. After determining the backlash "S2*" will be replaced by the correct "S2".

1. Drive in outer race of right-hand tapered roller bearing for differential (final drive cover side) without shims. Refer to «Differential, disassembling and assembling»(ref-289216-S07177048242008062700000) (install as far as it will go).
2. Insert differential into housing. Ring gear is positioned on right side (cover side).
3. Install cover and tighten bolts to 25 Nm.

Scheme 95

1. Install special tools VW 521/4 and 521/8 onto housing side in differential housing.
2. Turn cover side of differential housing upward.
3. Turn differential 8 turns in both directions so that tapered roller bearings settle.
4. Place measuring plate VW 385/17 onto differential.

Scheme 96

1. Install measuring tools.

A- = Dial gauge extension approx. 30 mm long

B- = Hex bolt M8 x 45

1. Place dial gauge extension on center of measuring plate VW 385/17.
2. Set dial gauge (3 mm measuring range) to "0" with 2 mm preload.

Scheme 97

1. Lift differential without turning; read play on dial gauge and note.

1. Measurement in following example: 0.50 mm

1. If it is required to repeat measuring sequence turn differential 8 turns in both directions, so that tapered roller bearings settle.

Determining "Stotal" (S1 + S2)

Determining thickness of shim "S1*"

Note. The preliminary adjustment shim "S1*" will be replaced with the final shim "S1" after determining the backlash. The total shim thickness "Stotal" remains unchanged.

1. Determine shim(s) as accurately as possible from table. Refer to «The following shims are available for "S1"»(ref-289216-S20809980372009020500000) .

Adjusting backlash

1. Drive pinion with shim "S3" installed
2. Differential with shims "S1*" + "S2*" installed

1. Insert differential in final drive housing, install cover and tighten all bolts to 25 Nm.
2. Turn differential 5 turns in both directions to settle tapered roller bearings.

Scheme 98

1. Assemble measuring equipment.
2. Use dial gauge extension VW 382/10 (6 mm flat).
3. Set measuring lever VW 388 to dimension "a" = 60 mm.
4. Determine play between teeth flanks as follows

1. Turn ring gear until it makes contact with a tooth flank (end of backlash travel).
2. Set dial gauge to "0" with 1 mm preload.
3. Turn ring gear back until it lies against an opposite tooth flank (backlash).
4. Read backlash and note value.

1. Turn ring gear through 90° and repeat measurements a further 3 times.

Determining average backlash

1. Result: The average backlash is 1.16 ÷ 4 = 0.29 mm

Note. If the individual measurements differ by more than 0.06 mm from each other, the installation of the ring gear or the final drive set itself is not correct. Check installation, replace final drive set if necessary.

Determining thickness of shim "S2"

1. Determine shim(s) as accurately as possible from table. Part numbers

The following shims are available for "S2"

1) Using the shim tolerance variations it is possible to find the exact shim thickness required. Insert two shims if necessary.

Determining thickness of shim "S1"

1. Determine shim(s) as accurately as possible from table. Part numbers

The following shims are available for "S1"

1) Using the shim tolerance variations it is possible to find the exact shim thickness required. Insert two shims if necessary.

Performing check measurement

1. Drive pinion with shim "S3" installed
2. Differential with shims "S1" (cover side) + "S2" (housing side) installed

1. Turn differential 5 turns in both directions so that tapered roller bearings settle.
2. Measure backlash four times on circumference.

1. Specifications: 0.12 to 0.22 mm

Note. If the backlash is outside the tolerance, the adjustments must be repeated. Refer to Determining thickness of shim "S2" . However, the total shim thickness "Stotal" must not be changed. The individual measurements must not differ by more than 0.06 mm from each other.