1973 OPEL GT-R differential

REAR AXLE
CONTENTS
SubjectPage No.
DESCRIPTION AND OPERATION:
Rear Axle Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4B- 7
DIAGNOSIS:
RearAxleTroubleDiagnosis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4B- 8
MAINTENANCE AND ADJUSTMENTS: (Not Applicale)
MAJOR REPAIR:
Removal and Installation of Rear Axle Assembly
Removal and Installation of Axle Shaft Assembly
Disassembly and Assembly of Differential
.* . . . . . . . . . . . .SPECIFICATIONS:
DifferentialSpecifications
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4B- 94B-10
48-l 1
4B-22
DESCRIPTION AND OPERATION
REAR AXLE DESCRIPTIONThe Opel rear axle is a semi-floating type that carries
car weight through the axle shafts by way of ball
bearings which are located on the outer ends of each
axle shaft. The rear axle assembly is attached to the
under body by way of the shock absorbers, track rod,
central joint support, and lower control arms. A sta-
bilizer rod is used on all Wagons, as well as Fast
Backs and Sedans. The GT is not equipped with a
stabilizer rod. The rear springs have a progressive
spring rate which is attained by a gradual reduction
of coil thickness. The springs are arranged between
the spring seats welded onto the rear axle tubes and
the under body side members. The upper and lower
ends are seated in profiled rubber dampening rings.
The differential housing is a malleable iron casting
with tubular axle housings pressed into the sides to
form a complete assembly. An oil feed passage to the
pinion bearings and an oil return hole are provided
to allow lubricant to circulate. A removable steel
cover is bolted on the rear of the differential housing
to permit service of the differential without removing
the rear axle assembly from the vehicle. A breather
fitting is located on top of the right axle tube.Within the differential carrier, the differential case is
supported by two tapered roller side bearings. These
side bearings are preloaded by shims located between
the bearing inner races and differential case. During
installation, varying the shim thickness from side to
side also determines the ring gear to pinion backlash.
The differential case houses two side gears meshed
with two pinions. The pinions and side gears are
backed by thrust washers. The pinion gears are held
in place by a pinion shaft which is anchored in the
differential case by a lock pin.
The inner end of the axle shafts engage and extend
through the splines of the side gears with a floating
tit.
The axle shafts have an enlarged diameter from mid-
shaft to the flange end.
A ball bearing and oil seal are used on all models, and
are pressed onto the outer end of the axle shaft as an
assembly.The drive pinion is mounted in two roller bearings in
the rear axle housing. Pinion setting is established by
shims located between the differential carrier and therear’pinion bearing outer race.

4S- 91973 OPEL SERVICE MANUAL
DIAGNOSIS
DIFFERENTIAL TROUBLE DIAGNOSISConditionPossible Cause
1. Noise is the same in1. a) Road noise.
“Drive” or “Coast”.b) Tire noise.
c) Front wheel bearing noise.
d) Front or rear U-joint angle
too great.
2. Noise changes on a2. a) Road noise.
different type of road.b) Tire noise.
3. Noise lowers tone as3. Tire noise.
car speed is lowered.
4. Similar noise is pro-4. a) Engine noise.duced with car standingb) Transmission noise.
and driving.c) Driveline angle.
5. Vibration5. a) Rough rear wheel bearing.
b) Tire unbalance.
c) Worn universal joint in
propeller shaft.
d) Front or rear U-joint angle
too great.
e) Mis-indexed, propeller shaft
at companion flange.
tJ Companion flange runout too
6. A knock or click6. A brinelled rear wheel bearing
approximately every two (2)
revolutions of rear wheel.
7. Noise most pronounced on7. Differential side gear and pin
turns.
8. A continuous low pitch8. Pinion bearing.
whirring or scraping noise
starting at relatively low
speed.9. Drive noise, coast9. Ring and pinion gear.
noise or float noise.
10. Clunk on accelera-
10. a) Worn differential cross sha
tion or deceleration.in case.
11. Groan in “Forward” or11. Wrong lube in differential.
“Reverse”.
12. Clunk or knock on12. a) Excessive end play of axle
rough road operation.to differential cross shaft
b) Excessive differential gear
clearance.

REAR AXLE48. 9
MAJOR REPAIRREMOVAL AND INSTALLATION OF REAR AXLE
ASSEMBLYRemoval
1. Raise rear of car with floor jack under differential
carrier and position jack stand under jack bracket on
each side of car. Remove rear wheel assemblies and
one brake drum.
2. Disconnect parking brake cable equalizer and re-
turn spring from brake rod.
3. Detach parking brake cable from actuator lever
and backing plate at wheel with brake drum
removed. Disconnect cable from lower control arm
brackets and pull loose end over exhaust system.
4. Disconnect shock absorbers at lower end.
5. Disconnect track rod at left end.
6. On cars equipped with a stabilizer rod, disconnect
the shackles at rear axle housing.7. Disconnect universal joint from pinion flange and
support or tie propeller shaft out of way after mark-
ing mating areas. If propeller shaft is removed, install
plug in rear of transmission to prevent loss of lubri-cant.8. Disconnect brake hose from brake pipe at differen-
tial and remove retaining clip.
9. Lower rear axle assembly far enough to remove
coil springs.
10. Remove central joint support bracket to under-
body retaining bolts.
11. Disconnect lower control arms at rear axle assem-
bly bracket and roll the assembly from under the car.
See Figure
4B-2.Installation
CAUTION: Fasteners in the following steps are impor-tant attaching parts in that they could affect the
performance of vital components and systems, and-
/or coo/d
resuJt in major repair expense. They must
be rep/aced with one of the same part number or withREAR SHOCK ABSORBERS
SPRING SEAT
4B-1Figure
4B-l Differential and Rear Suspension Assembly

REAR AXLE40- 11
Figure
48-3 Removing Axle Bearing Retaining Ring
seat and lateral runout of axle shaft flange near larg
est diameter.
Permissible radial runout is .002”, and permissible
“lateral runout is
.OO4”. An axle shaft which exceeds
these tolerances, or one which has been otherwise
damaged during removal, must be replaced.
2. Using installer ring J-21721-2, press on bearing so
that oil seal groove on bearing faces shaft splines.
3. Using installer ring J-21721-2, press on retainer
ring so that shoulder faces bearing.
Figure 48.4 Measuring for Axle Shaft Bearing Depth4. Check axle shafts end play as follows:
a. Using a depth gauge, measure depth of rear axle
bearing seat in axle housing (backing plate and gas-
kets in place). See Figure
4B-4.b. Measure width of bearing outer race. The differ-
ence between the two measurements indicates the
required thickness of the shims. The maximum per-
missible end play is .002”. If necessary to reduce end
play, add
,004” shims behind bearing as necessary. A
slight crush fit (up to ,006”) is desirable.
5. Coat rear axle shaft splines with hypoid gear lubri-
cant prior to installation.
6. Insert axle shaft into housing; using a mallet, drive
axle shaft completely into housing.
7. Install lock washers and nuts. Torque to 20
Ib.ft.8. Install brake drum and wheel assembly.
9. Remove supports and lower rear of car to floor.
DISASSEMBLY AND ASSEMBLY OF THE
DIFFERENTIALRemoval and installation of parts for service de-
scribed in the following sub-paragraph can be per-
formed with the rear axle assembly in the car. The
car must be raised and adequately supported to per-
mit access to the parts to be serviced.
Removal and Disassembly of Differential Case1. With car suitably supported at rear jack bracket
on each side, remove differential cover bolts and let
lubricant drain into suitable container.
2. Disconnect left end of track rod and wire to left
shock absorber.
3. Remove both rear wheels and brake drums.
4. Working through access holes in axle shaft flange,
remove four nuts and washers that retain the axle
shaft dust shield and brake backing plate to the axle
housing.
5. Unscrew rear axle shaft retaining plate.
6. Install axle shaft puller J-8805 coupled with slide
hammer J-2619 on axle shaft flange to remove rear
axle. In removing axle shaft, care should be exercised
to avoid damage to the oil seal. See Figure
4B-5.7. Remove differential cover and discard gasket.
8. Check and record ring gear backlash.

4S- 121973 OPEL SERVICE MANUAL
12. Insert adapter J-2241-1 1 in differential case bear-
ing hub and remove side bearings using puller J-22588 with adapter leg J-22939. See Figure
4B-6.13. Remove the differential case to ring gear bolts
and tap ring gear off case using a soft faced hammer.
14. Remove the differential pinion shaft retaining pin
using a
l/8” pin punch. See Figure 4B-7. Remove
pinion shaft, pinion gears, differential side gears and
thrust washers.
Figure 46.5 Removing Axle Shaft18
9. Mark differential side bearing caps and carrier
with a prick punch, so the caps can be reinstalled in
their original positions.
10. Remove differential side bearing cap bolts and
caps.11. Using two wooden hammer handles, pry differen-
tial case assembly from carrier. Do not drop or inter-
change differential side bearing outer races.
SIDE BEARING
PVLLER J-2258846.6
/NFigure
48-S Removing Differentiel Side BesrlngaPINION
SHAFTPINION
kSHAFT
LOCK PIN487
Figure 48-7 Removing Pinion Shaft Lock Pin
Removal and Disassembly of Drive Pinion
1. Remove torque tube assembly.
J-22932
SPLINE HOLDER4&8
Figure
48-E Removing Pinion Preload Nut

J-781 B INSTALLERiUNDERLINED
4B16Figure 46-16
- Pinion Gear Reference Number
NOTE: The digit “1’:when written in German, resembles
the digit
“7, However, the digit “7: when written in
German, always hasa horizontal line drawn rhrough it ,‘Z”).
4&17An example of how the above procedure should be
applied to calculate pinion depth using markings on
pinion is as follows:
1. Height block dimension
+ 1.4840.
2. Control figure (plus 10) converted to
f -.0039.
3. Difference between steps 1 and 2 it
1.4801.
4. Nominal figure
2 - 1.4680.
5. Shim thickness required
?r .0121.
6. Shim to closest thickness
+ .012.
4. Remove differential side bearing caps, gauging
arbor, gauge plate and pinion bearings.
5. Remove the rear pinion bearing outer race using
a brass drift.
6. Install pinion depth shims selected in Step
(f) in
the rear pinion bearing outer race bore and install the
rear pinion bearing outer race using installer J-78 18
and driver handle J-8092. See Figure 4B-18.
DRIVER.HANDLE
J-8092
48-12Figure 48.18 Installing Rear Pinion Bearing Outer
RaceI. Install rear pinion bearing onto the pinion using
installer J-21022. See Figure
4B-19.Figure 4B-19 Installing Rear Pinion Bearing
8. Lubricate pinion bearings and assemble the drive
pinion, collapsible spacer, front pinion bearing, oil
deflector plate and barrel spline sleeve in the differ-
ential carrier.
9. Thread barrel spline sleeve installer J-22938 onto
the drive pinion and draw the spline sleeve onto the
pinion until there are suflicient threads of the pinion

48. 16
1973 OPEL SERVICE MANUAL
protruding to install the pinion preload nut. Do
not use Installer J-22938 to adjust pinion preload.
See Figure 4B-20.
Assembly and Installation of Differential Case.
Opel 1900 and Manta1. Install side gears without thrust washers or shims.
BARREL SPLINE2. Lubricate and install pinion gears and thrust
washers between the side gears 180 degrees apart and
rotate the gears as an assembly until the pinion gear
bores are aligned with the pinion shaft bores in the
case.3. Install pinion shaft.
4. Install Special Tool J-24093 and, with the use of
a dial indicator, check end play clearance between
side gear and case as follows:
40-20a. Zero dial indicator on end of Tool J-24093. See
Figure 4B-22.
Figure 48.20 Installing Barrel Spline Sleeve
When the drive pinion end play is eliminated, the
preload specification is being approached. If this
specification is exceeded, replace the collapsible
spacer.10. Remove installer J-22938 and install washer and
pinion preload nut. Using Special Tool J-22932, hold
barrel spline and tighten preload nut until a preload
of 6-13
Ib.in. (9 Ibin. desired) with new bearings or
5-8
Ib.in. (6 lb.in. desired) with used bearings is re-
quired to rotate the drive pinion.
11. Use J-2293 1 to install a new pinion oil seal that
has been soaked in differential lubricant. See Figure4B-2
1.Figure 48.22 Zeroing Dial
lndicatotb. Using both hands, raise side gear until it bottoms
against case and record dial indicator reading. See
Figure 4B-23.
c. Measure the thickness of the concave thrust
washer by using a
0” to 1’ micrometer and subtract
this dimension from the dial indicator reading as
obtained in step b. Record dimension. See Figure
4B-24.
/INSTALLER J-22931d. After obtaining a dimension by subtracting con-48-21cave thrust washer thickness from dial indicator
reading, subtract an additional
,002 to obtain the
Figure 46.21 Installing Pinion Oil Sealcorrect shim thickness to be installed.

6. Before installing, shims must be measured to in-
sure that the proper thickness is being used. Install
shims of correct thickness to obtain desired clearance
and reassemble and install pinion shaft lock pin. In-
stall thrust washers with concave side towards differ-
ential case.
7. Using Special Tool J-24093, along with a foot-pound torque wrench, check torque to turn gears
using the following procedure:
a. Install axle shaft into a vise and position differen-
tial case onto axle shaft. See Figure
4B-25.Figure 48-23 Raising Side Gear Against Case
Figure 48.24 Measuring Concave Washer Thickness
AX,EXAMPLE:
1.Dial indicator reading * .095.
2. Subtract concave thrust washer thickness
+ -.oso.
3.Total + ,045.
4.Subtract an additional .002 *.002.
5. Shim thickness to be used
+ .043.
5. Turn case over and repeat the above procedure to
check other side gear to differential case clearance.Figure 48.25 Axle Shaft Installed in Vise
b. Insert Special Tool J-24093 into opposite side gear,
attach a torque wrench, and check torque to rotate
gear. S& Figure
4B-26. Permissible torque to turn
gears is 14
l/2 to 17 l/2 footpounds.
c. It is necessary to check rotating torque of both side
gears.8. If torque is not correct, it will be necessary to
reshim differential gears. Add first at one side one
shim of the next higher or lower thickness. If this is
not enough, reshim both sides completely.
9. Install ring gear on case making certain their mat-