1973 OPEL GT-R weight

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.

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

6A. 41973 OPEL SERVICE MANUAL
hand side above crankshaft sprocket, has a plunger
head with oil- proof and wear-resistant synthetic
rubber pad, which is pressed against chain by both
spring and oil pressure.
Figure 6A-2 Sectional View. Timing System
The top end of the short, light-weight hydrauricvalve
liffers is provided with a cup in which tits the
ball end of a stud engaged in an elongated hole in
rocker arm, thus maintaining transverse alignment
of the rocker arm.
The rocker
xrn is a steel stamping and pivots on
a ball secured by a self-locking nut on a stud screwed
into the cylinder head. This arrangement permits
easy valve clearance adjustment. All valves have oil
seals installed between valve spring and cap.
The
fuelpump is located at bottom left-hand side
of timing case and operated by, a cam integral with
distributor drive gear riveted
‘to distributor drive
shaft.
The aluminum alloy cast intake manifold with
smooth walls provide better charge of cylinders,
especially at high engine RPM. It is a four-port
manifold, i.e. there are separating walls between all
arms, one for each cylinder. An adapter for crank-
case ventilation hose leading to rocker arm cover is
arranged on front portion of intake manifold.Hot exhaust gases are used for heating a vaporization
plate located at bend of intake manifold below carbu-
retor and communicating with its tinned underside
with the interior of the exhaust manifold to ensure
that only vaporized fuel reaches the cylinders.
LUBRICATION SYSTEM AND OIL PUMPThe engine is lubricated by a forced feed system
Figure
6A-3 Oil Pump Pressure Relief Valve
Figure 6A.4 Rear Cross Sectional View

ENGINE MECHANICAL AND MOUNTS6A- 11
a. Attach left chain to alternator support rear bolt.
b. Bolt right chain to existing threaded hole at lower
right front of engine.
2. Assemble loose ends of chain to support device J-bolts and adjust to remove engine weight from motor
mounts.
3. Remove the two motor mount bracket to motor
mount retaining nuts.
4. Remove the two front suspension to frame rail bolt
retaining nuts.
5. Remove nut and bolt at lower end of steering shaft
U-joint.
6. With a floor jack under the center of the front
suspension cross member, raise car high enough for
wheels and suspension assembly to be rolled from
under car.
7. Position jack stands under both front jack brackets
on underbody to support car in this position.
8. Remove both front cross member support to frame
attaching bolts.
9. Remove brake pipe to brake hose retaining clips
at frame rails and disconnect brake hose from brake
pipes. Use an absorbent material or suitable con-
tainer for the brake fluid that will drain out.
10. Lower the front suspension assembly and remove
from under car.
11. Drain engine oil and remove oil pan and gasket.
Installation (Opel 1900 and Manta)1. Apply a light bead of sealer to the clean sealing
surfaces of the oil pan and affix a new gasket.
2. Bolt oil pan and gasket assembly to engine block.
3. Roll front suspension and floor jack under car and
raise into position careful to pilot the cross member
to frame rail attaching bolts and steering shaft to
their respective locations.
4. Install cross member’support to frame attaching
bolts and torque to 22 lb.ft.
5. Connect brake hose to brake pipes and install
retaining clips.
6. Bleed front brake system. Maintain brake fluid1Wd.
7. Remove jack stands and lower car.8. Install suspension to frame rail bolt retaining nuts.
9. Release and remove engine supporting device.
10. Install motor mount bracket to motor mount
retaining nuts.
11. Install steering shaft U-joint lower bolt and nut.
12. Replace engine oil.
Removal (GT Series)1. Support engine in vehicle using Tool J-23375. See
Figure 6A- 15.
Figure 6A-15 Engine Holding Fixture
Install tool by removing upper engine mount nut and
installing fixture. Replace nut and tighten. The en-
gine will now be supported by the tool, between the
frame rails. The front suspension need not be
removed on GT Models.
2. Drain oil.
3. Remove oil pan bolts and remove oil.
Installation (GT Series)1. Replace oil pan and bolts.
2. Remove engine holding fixture and replace engine
mounts.
3. Replace engine oil.

ENGINE MECHANICAL AND MOUNTS6A- 17
seating and to prevent turning.The ends of she//s
must never be tiled flush with parting surface of
crankcase or bearing cap.Crankshaft bearings are the precision type which do
not require reaming to size. Shims are not provided
for adjustment since worn bearings are readily re-
placed with new bearings of proper size. Bearings for
service replacement are furnished in standard size
and undersizes. Under no circumstances should
crankshaft bearing caps be tiIed to adjust for wear in
old bearing.After removal of oil pan, pipe and screen assembly,
perform the following removal, inspection and in-
stallation operations on each crankshaft bearing in
turn so that the crankshaft will be well supported by
the other bearings.
If crankshaft has been removed to check straightness
the following procedure is suggested. Rest crank-
shaft on “V-blocks” at number one and number live
main bearing journals. Check indicator runout at
No. 3 main bearing journal. Total indicator reading
should not exceed
.C012”.1. Since any service condition which affects the
crankshaft bearings may also affect the connecting
rod bearings, it is advisable to inspect connecting rod
bearings
first. If crankpins are worn to the extent
that crankshaft should be replaced or reground, re-
placement of crankshaft bearings only will not be
satisfactory.
If replacement of cylinder block or crankshaft is re-
quired, always check main bearing clearance with
plastic-type gauge to obtain specified limits.
2. Remove one bearing cap, then clean and inspect
lower bearing shell and the crankshaft journal. If
journal surface is scored or ridged, the crankshaft
must be replaced or reground to insure satisfactory
operation with new bearings. Slight roughness may
be polished out with tine grit polishing cloth
thoroughly wetted with engine oil, and burrs may be
honed off with a tine stone.
3. If condition of lower bearing shell and crankshaft
journal is satisfactory, check the bearing clearance
with a plastic-type gauge.
4. When checking a crankshaft bearing with plastic-
type gauging material, turn crankshaft so that oil
hole is up to avoid dripping of oil on the gauge
material. Place paper shims in lower halves of adja-
cent bearings and tighten cap bolts to take the weight
of crankshaft
off the lower shell of beating being
checked.5. If bearing clearance exceeds
.C03”, it is advisable
to install a new bearing; however, if bearing is in
good condition and is not being checked because ofbearing noise, it is not necessary to replace the bear-
ing.6. Loosen all crankshaft bearing cap bolts
l/2 turn,
and remove cap of bearing to be replaced.
7. Remove upper bearing shell by inserting Bearing
Shell Remover and Installer J-8080 in oil hole in
crankshaft, then slowly turning crankshaft so that
the tool rotates the shell out of place by pushing
against the end without the tang. See Figure
6A-27.When turning crankshaft with rear bearing cap
removed hold oil seal to prevent it from rotating out
of position in crankcase.
8. The crankshaft journal cannot be measured with
an outside micrometer when shaft is in place; how-
ever, when upper bearing shell is removed the jour-
nal may be checked for out-of-round by using a
special crankshaft caliper and inside micrometer.
Figure 6A-27 Removing and Installing Crankshaft
Bearing Upper Shell
The caliper should not be applied to journal in line
with oil hole.
If crankshaft journal is more than
.M)12” out-of-
round, the crankshaft should be replaced since the
full mileage cannot be expected from bearings used
with an excessively out-of-round crankshaft.
9. Before installation of bearing shells make sure that
crankshaft journal and the bearing seats in crankcase
and cap are thoroughly cleaned.
10. Coat inside surface of upper bearing shell with
engine oil and place shell against crankshaft journal
so that tang on shell will engage notch in crankcase
when shell is rotated into place.
11. Rotate bearing shell into place as far as possible
by hand, then insert Installer J-8080 in crankshaft oil
hole and rotate crankshaft to push shell into place.
Bearing shell should move into place with very little

6A. 201973 OPEL SERVICE MANUAL
diameter at the right angle to the piston pin is greater
than the diameter parallel to the piston pin. When a
piston is checked for size, it must be measured with
micrometers applied to the skirt at ,points 90 degrees
to the piston pin. See Figure
6A-32. The piston
should be measured (for fitting p&poses) 2
l/2 in-
ches below the top of piston.
MEASURE AT
Figure 6A-32
Measuring,PistonInspect bearing surfaces of piston pins. Check for
wear by measuring worn and unworn surfaces with
micrometers. Rough or worn pins should be re-
placed. Check fit of piston pins in piston bosses.
Occasionally pins will be found tight due to gum or
varnish deposits. This may be corrected by removing
the deposit with a suitable solveni. If piston bosses
are worn out-of-round or oversize, the piston and pin
assembly must be replaced. Oversize pins are not
practical because the pin is a press fit in the connect-
ing rod. Piston pins must tit the piston with
0X4”to
.OCHl7” clearance.
Examine all piston rings for scores, chips or cracks.
Check compression rings for tension by comparing
with new rings. Check gap of compression rings by
placing rings in bore at bottom of ring travel. Meas-
ure gap with feeler gage. Gap should be between
,011” and .02.1”. If gaps are excessive (over .021”) it
indicates the rings have worn considerably and
should be replaced.
No attempt should be made to cut down oversize
pistons to fit cylinder bores. This practice
will de-
stroy the surface treatment and affect the weight.
The
sma/Jest possible oversize service pistons shouId
be used and the cylinder
bores should be honed to
size for proper clearance.1. Before installing piston, piston rings, or reboring
cylinders, observe the following:Cylinder bores may not be the same size. Standard
replacement piston sizes are in the midpoint of the
cylinder bore size range. Therefore, it may be neces-
sary to hone cylinders for correct piston tit. Out-of-
round on cylinder bore must not exceed
.ooO5”maximum with a taper of not over
.OilO5”.Before the honing or reboring operation is started,
measure all new pistons with micrometer contacting
at points exactly 90 degrees to piston pin (Figure6A-32) then select the smallest piston for the first
fitting. The slight variation usually found between
pistons in a set may provide for correction if the first
piston has excessive clearance.
If wear of cylinder does not exceed
.005” honing is
recommended for truing the bore. If wear or
out-of-round exceeds these limits, the bore should be trued
up with a fly cutter boring bar and then finish honed.
When reboring cylinders, all crankshaft bearing caps
must be in place and tightened to proper torque to
avoid distortion ofbores in final assembly. Always be
certain the crankshaft is out of the way of the boring
cutter when boring each cylinder. When making thefinal cut with boring bar, leave
,001 w on the diameter
for finish honing to give the required clearance speci-
fied.When honing cylinders, use clean sharp stones of
proper grade for the required amount of metal to be
removed, in accordance with instructions of the hone
manufacturer. Dull or dirty stones cut unevenly and
generate excessive heat. When using coarse or
medium grade stones use care to leave sufficient
metal so that all stone marks may be removed with
the fine stones used for finishing in order to maintain
proper clearance.
When finish honing, pass the hone through the entire
length of cylinder at the rate of approximately 60
cycles per minute. This should produce the desired
45 degree cross hatch pattern on cylinder walls
which will insure maximum ring life and minimum
oil consumption.
It is of the greatest importance that refinished cylin-
der bores have not over
.0005” out-of-round or ta-
pered. Each bore must be final honed to remove all
stone or cutter marks and provide a smooth surface.
During final honing, each piston must be fitted in-
dividually to the bore in which it will be installed and
should be marked to insure correct installation.
After final honing and before the piston is checked
for fit, each cylinder bore must be thoroughly
washed to remove all traces of abrasive and then
dried. The dry bore should then be brushed clean
with a power-driven iibre brush. If all traces of abra-
sive are not removed, rapid wear of new pistons and
rings will result. Fit new pistons in the following
manner:

78.221973 OPEL SERVICE MANUAL
3. Install new bellows. Adhere to distance A
- 8.07”.
See Figure 7B-I 1.
4. Heat up new gearshift lever knob in boiling water
to 176 degrees F. and push it onto gearshift lever
tube. Adhere to distance A .3”, see Figure
7B-15.The gearshift lever tube end is provided with trans-
verse grooves for which reason the old button cannot
be reused. Install gearshift lever.
REPLACING RUBBER DAMPENING PARTS IN
GEARSHIFT LEVER1. Remove gearshift lever.
2. Knock off gearshift lever button and loosen
threaded pin for Bowden control wire attachment.
3. Remove lower snap ring from gearshift lever tube
and pull tube off shift finger.
4. Take off and replace rubber dampening parts.
5. After installation of tube, tighten Bowden control
wire with threaded pin. Prior to tightening, pull ring
must rest on gearshift lever tube and clamping block
on pull ring. See Figure
7B-15.6. Heat up new gearshift lever knob in boiling water
to 176 degrees F. and push it onto gearshift lever
tube. Adhere to distance A
- .3”, see Figure 7B-15.The gearshift lever tube end is provided with trans-
verse grooves for which reason the old button cannot
be reused.
7. Install gearshift lever.
MAJOR REPAIR
TRANSMISSION REMOVAL1. Remove air cleaner. Remove throttle rod from
carburetor and rear support and disconnect battery.
2. Remove screws from fan shroud.
3. Remove gearshift lever (refer to paragraph on ser-
vicing gearshift lever).
4. Support car with frame or wheel stands in the
front or frame stands in the rear.
5. Loosen front exhaust pipe to manifold flange.
6. Remove clutch cable from fork by pushing fork to
disengage the clutch and unsnap cable from slot.
7. Disconnect both wires from backup lamp switch.8. Disconnect speedometer cable from transmission
case extension housing.
9. Unhook parking brake cable return spring and
remove cable adjusting nut, equalizer, and spacer.
See Figure
7B-16.PARKING BRAKE CABLE
PARKING BRAKE
Figure 78-16 Parking Brake Equalizer and Return
Spring
9. Disconnect drive shaft at central joint and remove
as follows: See Figure
7B-16.a. Disconnect parking brake cable equalizer from
rod.b. Mark the mating parts of U-Joint and the drive
pinion extension shaft flange.
c. Loosen bolt locks and remove bolts or nuts.
d. Work propeller shaft slightly forward, lower rear
end of shaft and slide assembly rearward. Remove
thrust spring.
e. Install a plug in the rear of the transmission to
prevent loss of lubricant.
10. Remove rear engine mount bolts and lower trans-
mission as far as possible.
11. Remove transmission case to clutch housing at-
taching bolts and remove transmission.
INSTALLATION OF TRANSMISSION WITH
ENGINE IN CAR1. Make certain main drive gear splines are clean and
dry. Also, make certain the transmission is in Neu-
tral so that the main drive gear splines may be in-
dexed when making the installation.
2. Install transmission and support weight while in-
stalling transmission case to clutch housing bolts.
3. Install rear engine mount.
4. Install propeller shaft, align, and tighten U-Joint
to pinion flange U-Bolt nuts and torque to 11 lb. ft.

7C- 521973 OPEL SERVICE MANUAL
CCUMULATOR
DRIVE:--7633
Figure 7C-33 1
- 2 Accumulator Valve
The ports and spools operate as previously described.
However, for increased engine torque, it is necessary
to increase the accumulator pressure. This is accom-
plished by introducing modulator pressure to the
small end of the 1-2 accumulator valve. As the
modulator pressure increases, it adds to the spring
force and increases the l-2 accumulator pressure.
The 1-2 accumulator pressure is fed to the bottom
(spring loaded side) of the 1-2 accumulator piston.
The Governor is mounted on the output shaft and
contains two interconnected regulating valves See
Figure
7C-34. Its purpose is to supply an oil pressure
5 8I. GOVERNOR SECONDARY VALVE6
SPRING RETAINER
2. GOVERNOR SECONDARY VALVE SPRING
3. GOVERNOR SECONDARY VALVE
4. GOVERNOR PRIMARY VALVE
5. GOVERNOR BODY6. ROLL PINIC~VFigure 7C-34 Governor Assemblythat is a function of output shaft or car speed. Line
pressure is supplied to the governor from the Manual
Valve (to be covered later). The governor operates on
the principle of centrifugal force. That is, as an object
spins off center at changing speeds, its outward force
is a function of the rotating speed.
Line pressure is directed to the outer-most port of the
secondary valve. The secondary spring holds the
valve in an outward position so that the outer spool
of the valve is open to “line”. As the line pressure
builds up between the spools, it exerts a force on the
larger diameter inner spool to start counteracting the
spring. When the hydraulic force is large enough, it
moves the valve inward against the spring force until
the outer spool closes the line port. If the pressure
between the spools still creates a force larger than the
spring force, the valve will continue to move inward
until the excess pressure opens to the exhaust port.
The valve then regulates between the line and ex-
haust port.
A fixed governor pressure in the secondary valve has
now been established with no rotation of the output
shaft. As the governor begins to rotate, the outward
force (due to the weight of the secondary valve) is
added to the force of the spring. Therefore, as the
speed increases, the outward force and in turn the
secondary valve pressure increases.
The secondary valve pressure is directed to the feed
port of the primary valve. With no rotation of the
governor, the pressure acts against the large inner
spool and forces it to open to the exhaust port. Since
there is no spring force on the primary valve, it will
continue to keep the feed port closed and the exhaust
port open. The final governor pressure is then zero.
As the governor begins to rotate, the weight of the
primary valve creates an outward force working
against the oil pressure. The pressure in the primary
valve port now increases as a function of speed. This
continues up to the speed where the outward force
finally holds the primary valve outward, keeping the
feed port open.
In summary, at zero speed, the governor pressure is
zero. As the speed increases, the governor pressure
will increase as dictated by the primary valve until
the speed is great enough to hold the primary valve
all the way out. At speeds above this point, the gover-
nor pressure is established by the secondary valve.
Governor pressure is then directed to:
Modulator Valve.
1 - Two Shift Valve.
2
- Three Shift Valve.
3 High Speed Downshift Timing Valve.