1973 OPEL GT-R service

4A- 21973 OPEL SERVICE MANUAL
PROPELLER SHAFT AND CENTRAL JOINT
CONTENTS
Subject
DESCRIPTION AND OPERATION:
PropellerShaftandCentralJoint. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DIAGNOSIS: (Not Applicable)
MAINTENANCE AND ADJUSTMENTS: (Not
Applicable)
MAJOR REPAIR:
’Propeller Shaft Removal andInstallation
. . . . . . . ..-....Disassembly andAssembly of CentralJoint
. . . . . . . . . . . .SPECIFICATIONS:
Propeller Shaft and Central Joint Specifications . .
DESCRIPTION AND OPEqATlON
PROPELLER SHAFT AND CENTRAL JOINTDue to the use of both automatic and manual trans-
missions, propeller shafts of various lengths are re-
quired depending upon vehicle, engine, and
transmission (manual or automatic) application. The
propeller shaft is of a strong design due to increased
engine torque. It is also a one piece tubular shaft, but
it has two universal joints. See Figure 4A-1. The
front universal joint attaches to the transmission out-
put shaft by a splined slip joint. The rear universal
joint attaches to the pinion extension shaft flange by
Page No.
4A-2
4A-3
4A-3
4A-6two U-bolts. The splines of both propeller shafts are
lubricated internally with transmission lubricant. An
oil seal in the rear of the transmission extension pre-
vents loss of lubricant and entrance of harmful for-
eign material.
The torque tube which houses the drive pinion exten-
sion shaft is bolted to the differential housing. The
torque tube is pivoted in rubber elements of the cen-
tral joint support bracket which is bolted to the floor
panel. The support bracket and rubber parts of the
torque tube
arc termed the central joint. The front
end of the drive pinion extension shaft rides in a ball
bearing mounted in rubber in the central joint.
CENTRAL JOINT\REAR U-JOINT
FRONT U-JOINT
4A-1Figure 4R1 Propeller Shaft

4A- 41973 OPEL SERVICE MANUAL
Figure 4A-3 Removing Pinion Flange
bracket to support cushion bolts and pull central
joint support from torque tube. See Figure 4A-5;
Assembly of Central Joint
CAUTION: Fasteners in the following steps are impor-
tant attaching parts in that they could
ah&t the
performance of vital components and systems, and-
/or could result in major
repair expense.They must
be replaced with one of the samepartnumber or with
an
equivalentpart ifreplacement becomes necessary.
Do not use a replacement part of lesser quality or
substitutk design. Torque vah~es must be used as
specitied dun’ng reassembly to assure proper reten-
. lion of these parts.TORQUE TUB;
Figure
4A-5 Disassembling Central Joint
Figure
4A-6 Support Cushions Installed on Torque
.TubeTORQUE TUBE
Figure 4A-4 Removing Drive Pinion Extension Shah

4A- 61973 OPEL SERVICE MANUAL
SPECIFICATIONSPROPELLER SHAFT AND CENTRAL JOINT
SPECIFICATIONS
Tightening Specifications ~
Use a reliable to’rque wrench. Specifications are for clean and lightly-oiled
threads.
Part
Bolt
Bolt
BoltTorque
BoltLocation
Drive Pinion Extension Shaft Flange to Universal
Joint
.._.....................................................................Central Joint Support to Underbody
_.._....._........._..........CentralJointSupport toRubber Cushion
Tube Rubber Cushion to Torque Tube
._.........._...............Support
CushionTorque
Lb.Ft.
1136
15

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.

4B- 101973 OPEL SERVICE MANUAL
Figure 48-Z Removing Rear Axle Assemblyan equiva/entpart ifreplacement becomes necessary.
Do not use a replacement
part of lesser quality or
substitute design. Torque
values must be used as
specified
during reassembly to assure proper reten-
tion of these parts.1. Roll rear axle assembly under car on floor jack and
loosely attach lower control arms to rear axle hous-
ing.
2. Attach central joint support, to underbody with
bolts only finger tight.
3. Lower rear axle assembly, install lower damper
rings in spring seats, coil springs and upper damper
rings on springs. Make certain the damper rings and
springs are properly positioned.
4. Install track rod on axle housing.
5. On Opel 1900 and Manta, place a load of approxi-
mately 350
Ibs. in luggage conipartment or on the
GT, place a load of approximately 150 lbs. on drivers
seat and raise rear axle far enough for underbody to
clear jack stands.
6. Torque central joint support t$ underbody bolts to
36 lb.ft.
7. Torque lower control arm to
Axle housing bolts to
18
Ib.ft. on the GT and 22 lb.ft. dn the Opel 1900 and
Manta.
8. Torque track rod to rear axle attaching nut to
40lb.ft. on the GT and to 76
lb.ft. on the Opel 1900 and
Manta and remove added weight.
9. Install shock abosrbers and tighten nuts to 15
Ib.ft.on the GT and to 47
Ib.ft. on the Opel 1900 and
Manta.10. If car is equipped with stabilizer rod, connect
shackles to axle housing. Tighten to 25 lb. ft.
11. Connect brake hose to brake pipe and install
retaining clip.
12. Thread parking brake cable over exhaust system
and connect to lower control arm brackets, parking
brake actuating lever and brake backing plate. Install
brake drum.
13. Align mating marks and connect propeller shaft
to pinion flange. Tighten universal joint attaching
bolts to 11
Ib.ft. Bend respective lock plate tabs to
secure nuts or bolts.
14. Connect parking brake cable equalizer and return
spring to brake rod and adjust to specifications.
15. Bleed rear brake system and fill master cylinder.
16. Install wheel assemblies and tighten lug nuts to
65
lb.ft.17. Remove jack stands and lower car to the floor.
REMOVAL AND INSTALLATION OF AXLE SHAFT
ASSEMBLY
Removal1. Raise and support rear of car at jack brackets.
2. Remove wheel and brake drum as necessary.
3. Unscrew rear axle shaft retaining plate and with
axle shaft puller J-8805 coupled with slide hammer
J- 2619 on axle shaft flange, remove axle shaft.
4. For replacement of the bearing parts, first remove
retaining ring by cutting off with a chisel. See Figure4B-3.
5. Press off bearing, using rear pinion bearing
remover J-22912.
Installation
CAUTION: Fasteners in the following steps b are im-
portant attaching parts in that they could at&t
tee
performance of vital components and systems, and-
/or could result in major
repair expense.They must
be replaced with one of the same part number or with
an equivalentpart ifreplacement becomes necessary.
Do not use a replacement part of lesser quality or
substitute design Torque values must be used as
specified
during reassembly to assure proper reten-
tion of these parts.1. Check radial runout of axle shaft at ball bearing

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