1973 OPEL GT-R tire pressure

IoC-91973 OPEL SERVICE MANUAL
Figure OC-5 Brake Master Cylinder
I
Figure OC-6 Tire Rotation Methods
when the clutch pedal has in excess of 1
l/4 inch fr&
travel. See Figure OC-7.
Rear Axle
Change lubricant every
12,ooO miies when vehicle is
used for pulling a trailer.
Cooling SystemCheck at 12-month or
12,000~mile intervals, wash
radiator cap and filler neck with clean water, pres-
sure test system and radiator cap for proper pressure
holding capacity (tighten hose clamps and inspect
condition of all cooling and heater hoses). Replace
hoses every 24 months or 24,000 ,miles or earlier :if
checked, swollen or otherwise deteriorated.
Also each 12 months or
12,ooO miles, clean exteribr
of radiator core. Every 24 months or
24,OCO miles,Floor-Pan
-Clutch Pedal
Figure OC-7 GT Clutch Lash
drain, flush, and refill the cooline svstem with a new
coolant so&ion of permanent
6~; anti-freeze and
water for protection-of -20°F.
D-6 NOT REMOVE
RADIATOR CAP WHEN SOLUTION IS HOT
AND UNDER PRESSURE.
Wheel BearingsClean and repack front wheel bearings with a lubri-
cant as specified on the lubrication chart, Figure
oc-1.
Automatic Transmission FluidUnder normal driving conditions, change the trans-
mission fluid every 24,000 miles. Under unusual con-
ditions such as constant driving in heavy city traffic
during hot weather, trailer pulling, etc., this service
should be performed at
12,COO mile intervals.
General Motors DEXRON Automatic Transmis-
sion Fluid, which has been especially formulated and
tested for use in your automatic transmission, is
recommended. Other automatic transmission fluids
identified with the mark DEXRON are also recom-
mended.
Check the fluid level at each engine oil change
period. To make an accurate fluid level check:
1. Drive car several miles, making frequent starts and
stops, to bring transmission up to normal operating
temperature (approximately
180-190’F.)2. Park car on a level surface.
3. Place selector lever in “Park” and leave engine
running.

LUBRICATION AND MAINTENANCE OC-9
4. Remove dipstick and wipe clean.
5. Reinsert dipstick untip cap seats.
6. Remove dipstick and note reading.
If fluid level is at, or below the ADD mark, add
sufficient fluid to rais the level to the FULL mark.
One pint raises the level from ADD to FULL. Do
not overfill.
3OC8Figure OC-8 Automatic Transmission Dipstick
SAFETY MAINTENANCE
Brake Lines and HosesCheck for proper attachment, leaks, cracks, chafing,
deterioration, etc. Any questionable parts noted
should be replaced or repaired immediately. When
abrasion or wear is evident on lines or hoses, the
cause must be corrected.
Tires and WheelsCheck tires for excessive wear, nails, glass, cuts or
other damage. Make certain wheels are not bent or
cracked and wheel nuts are tight. Uneven or abnor-
mal tire wear may indicate the need for alignment
service. Tire inflation pressure should be checked by
the owner at least monthly, or more often if daily
visual inspection indicates the need.
Exhaust SystemCheck complete exhaust system and nearby body
areas and trunk lid for broken, damaged, missing orm&positioned parts, open seams, holes loose connec-
tions or other deterioration wiuch could permit ex-haust fumes to seep into the trunk or passenger
compartment. Dust or water in the trunk may be an
indication of a problem in one of these areas. Any
defects should be corrected immediately. To help
insure continued integrity, exhaust system pipes and
resonators rearward of the muftler must be replaced
whenever a new mufIler is installed. Use genuine
GM parts specified for the vehicle.
Engine Drive BeltsAdjust belts driving fan, alternator and other acces-
sories at first 4 months or
6,ooO miles of vehicle
operation. At each subsequent 4 month/6,000 mile
interval, check belts for cracks, fraying, wear and
tension. Adjust or replace as necessary. It is recom-
mended that belts be replaced every 24 months or
24,C00 miles, whichever occurs first.
Suspension and SteeringCheck for damaged, loose or missing parts, or parts
showing visible signs of excessive wear or lack of
lubrication in front and rear suspension and steering
system. Questionable parts noted should be replaced
without delay.
Safety Checks to be Performed by OwnerListed below are the safety checks that should be
made by the owner (items a thru t). These checks
should be made at least every 4 months or
6,ooOmiles, whichever occurs first, or more often when the
need is indicated. Any deficiencies should be brought
to the attention of your dealer or another service
outlet, as soon as possible, so the advise of a qualified
mechanic is available regarding the need for repairs
or replacements.
A. Steering Column Lock
_ Check for proper operat-
ion by attempting to turn key to LOCK position and
turning steering wheel with car stationary. Steering
wheel should turn as long as key remains in lock.
When key is removed steering wheel should lock.
Key should be removable only in LOCK position.
B. Lap and Shoulder Belts
- Check belts, buckles,
retractors and anchors for cuts, fraying or weakened
portions, loose connections, damage, and for proper
operation. Check to make certain that anchor
mounting bolts are tight.
C. Steering
- Be alert to any changes in steering
action. The need for inspection or servicing may
beindicated by “hard” steering, excessive free play or
unusual sounds when turning or parking.
D. Windshield Wipers and Washers
- Check operat-
ion of wipers, as well as condition and alignment of

!
OC-12 1973 OPEL SERVICE MANUAL iExhaust Gas Recirculation Systep
Check system operation at 12 &onth/12,000 mile
intervals. Clean valve and EGR &usages if required;
A valve with a damaged diaphragm must be re-
placed.I
Engine CompressionTest engine cranking compressi& If a problem
exists, correct it Minimum compression recorded;
many one cylinder should not be less that 70% ‘of
highest cylinder. For example, if fhe highest presstire
in any one cylinder is 150 pounds, the lowest
alloka-ble pressure for any other cylinder would be
l-05pounds (150
x 70% = 105).~
Fuel Cap, Fuel Lines and Fuel TankInspect the fuel tank, cap and lines for damage which
could cause leakage. Inspect fuel cap for correct seal-
ing ability and indications of physical damage. Re-
place any damaged or malfunctionining parts.
Air Cleaner ElementReplace the engine air cleaner element under normal
operating conditions every 24,000 miles. Operation
of vehicle in dusty areas will necessitate more fre-
quent element replacement.
CAUTION: Do not operate the engine with-
out the air cleaner unless temporary re-
moval is necessary during repair or
maintenance of the vehicle. When the aircIeaner is removed, backfiring can cause
fire in the engine compartment.

1F. 46 1973 OPEL SERVICE MANUAL
’
/
Headlight High-Low Beam Control and Passing:
SignalI
When the headlights have been switched on, high
and low beam selection is made by raising the direc-
tional signal lever toward steering wheel. Each
ti&the lever is raised, beam position, will change.
When the headlights are not on, a flashing headlight
signal may be given by raising and lotiering the di-
rectional signal lever. With the headlights on and
inlow beam position, raising and lowering the direc-
tional signal lever will also cause the headlights to
flash.
Fog Light SwitchAll Rallye models are equipped with two white f?g
lights mounted below the front bumper.
The fog light toggle switch is located on the
insty-ment cluster to the left of the temperature and
fuelgauge cluster.
/
The fog lights can be turned off at any time by the
toggle switch, but can only be tyrned on when: :
1. The ignition switch on or the
?gine running.!
2. The fog light toggle switch lower half is pushed
in.3. The parking lights and/or low beam headlights
are
OKThe fog lights are automatically turned off if the
ignition switch is on and the headlights are switched
to high beam position.
Courtesy LightThe courtesy light illuminates the interior of the Car
when any door is opened. The courtesy light can also
be turned on with all doors closed by tilting the l&s.
GT Headlamp MechanismThe concealed headlamps are moved mechanically.
Pushing actuating lever on left side of console opens
headlamps and pulling lever closes headlamps. Two
(2) meshing gear segments convert the movement, of
the lever to a rotation of 180 degrees. The pivots of
the headlamps lie below the centerline so that with
headlamps in closed position, the headlamp housing
is flush with front sheet metal. Refer to Group 110,
Section “F”, for service procedures on the GT head-
lamp mechanism.
A white indicator lamp in the instrument panel lights
if the headlamps are not completely opened lorclosed The switches of the headlamp electrical sys-
tem are located behind the left headlamp operating,
mechanism.
MAINTENANCE AND ADJUSTMENTSHEADLAMP AIMING
The headlamps must be properly aimed in order to
obtain maximum road illumination and safety that
has been built into the headlighting equipment. With
the Guide T-3 type sealed beam units, proper aiming
is even more important because the increased range
and power of this lamp make even slight variations
from recommended aiming hazardous to approach-
ing motorists. The headlamps must be checked for
proper aim whenever a sealed beam unit is replaced
and after an adjustment or repairs of the front end
sheet metal assembly.
Regardless of method used for checking headlamp
aim, car must be at normal weight, that is, with gas,
oil, water, and spare tire. Tires must be uniformly
inflated to specified pressure. If car will regularly
carry an unusual load in rear compartment, or a
trailer, these loads should be on car when headlamps
are checked. Some States have special requirements
for headlamp aiming adjustment, and these require-
ments should be known and observed.
Horizontal and vertical aiming of each seal beam
unit is provided by two adjusting screws which move
the mounting ring in the body against the tension of
the coil spring. There is no adjustment for focus,
since the sealed beam unit is set for proper focus
during manufacturing assembly.
MAJOR REPAIRHEADLIGHT SWITCH
- OPEL 1900. MANTA
Removal1. Remove instrument cluster cover panel. See Sec-
tion H.
2. Compress retaining springs and pull switch out.
See Figure 1 F-
1.3. Pull multiple socket off switch.
Installation
1: Plug multiple socket in switch and push switch in
panel until clips lock in place.
2. Replace instrument cover and secure with two (2)
screws.

3C-22 1973 OPEL SERVICE MANUAL.
FRONT END ALIGNMENT
CONTENTS
SubjectPage No.
DESCRIPTION AND OPERATION:
FrontWheelAlignment
. . . . . . . . . . . . . . . . . . . . . . ..“...........................DIAGNOSIS: (Not Applicable)
MAINTENANCE AND ADJUSTMENTS:
Inspection Before Checking Front Wheel Alignment
AdjustingCaster
. . . . . . . . ...’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Adjusting Camber
. . . . . . . . . . . . . . . . . . . . . . . . . . * . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Adjusting Toe-In
. . . . . . . . . . . . . . * . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .King Pin Inclination
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MAJOR REPAIR: (Not Applicable)
SPECIFICATIONS:3C-223C-223C-233C-253C-253C-26
Wheel Alignment Specifications
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3C-26
DESCRIPTION AND OPERATIONFRONT WHEEL ALIGNMENT
Wheel alignment is the mechanics of adjusting the
position of the front wheels in order to attain the
least steering effort with a minimal amount of tire
wear.handling, but require only reasonable accuracy to
provide normal tire life. With the type of front sus-
pension used, the toe-in adjustment is much more
important than caster and camber are as far as tire
wear is concerned.
Correct alignment of the chassis is essential to proper
alignment of front and rear wheels. Briefly, the es-
sentials are that the frame must be square in plain
view within specified limits, that the top and bottom
surfaces of the front cross member must be parallel
fore and aft, and that the upper and lower control
arm must be at correct location in respect to shafts
and the front cross member. All bushings, ball joints
and bolts must be of proper torque and in usable
condition.Caster and camber adjustments need not be consid-
ered unless visual inspection shows these settings to
be out, or unless the car gives poor handling on the
road. In the majority of cases, services consisting of
inflating tires to specified pressure and interchanging
tires at recommended intervals, balancing all wheels
and tires, adjusting steering gear and setting toe-in
correctly will provide more improvement in car han-
dling and tire wear than will other front end align-
ment adjustments.
Wheel and tire balance has an important effect on
steering and tire wear. If wheels and tires are out of
balance, “shimmy” or “tramp” may develop or tires
may wear unevenly and give the erroneous impres-
sion that the wheels are not in proper alignment. For
this reason, the wheel and tire assemblies should be
known to be in proper balance before assuming that
wheels are out of alignment.The correct use of accurate front end alignment
equipment is essential to determine whether front
suspension parts have been damaged by shock or
accident, and to obtain correct alignment settings
after new parts have been installed.
MAINTENANCE AND ADJUSTMENTS
Inspection Before Checking Front Wheel AlignmentClose limits on caster, front wheel camber, andBefore making any adjustment affecting caster, cam-
theoretical king pin inclination are beneficial to carber, toe-in, theoretical king pin inclination, or
steer-

FRONT END ALIGNMENT 3C-23
ing geometry, the following checks and inspections
must be made to insure correctness of alignment
equipment readings and alignment adjustments.
1. The front tires should have approximately the
same wear and all tires must be inflated to specified
pressures (see Wheel and Tire Specifications
- Sec-
tion 3G).
2. Check front wheel bearings for looseness and ad-
just if necessary (see Front Suspension Adjustments
- Section 3A).
3. Check for run-out of wheels and tires, (see Section
3G).
4. Check wheels and tires for balance and correct if
out-of-balance (See Section 3G).
5. Check for looseness at ball joints and tie
rdd ends;
if found excessive, it must be
corxcted before align-
ment readings will have any value.
Figure SC-Z Spring Compressor J-2 1689 Installed
6. Check shock absorber action and correct if neces-
sary. Consideration must be given the optional
equipment on the car, undercoating, dirt, etc.
7. It is advisable to check the condition and accuracy
of any equipment being used to check front end
alignment and to make certain that instructions of
the manufacturer are thoroughly understood.
ADJUSTING CASTER (GT)
4. Remove upper control arm shaft,
5. Remove upper control arm from shock absorber
support, being careful not to lose toothed washers.
6. Adjust caster by installing selective toothed wash-
ers on both sides of control arm shaft, between con-
trol arm and shock absorber support. Never use
CAUTION: Front suspension fasteners are impor- more than one washer at any one location. The total
tant attaching parts in that they could
affectthickness, front and rear washer, must equal .48”.
the performance of uital components and sys-
tems, and/or could result in major repair expense.
There are only two possible caster changes that can
be made.
They must be replaced with one of the same
part
number or with an equiualentpart ifreplacement
becomes necessary. Do not use a replacement part
Of lesser quality or substitute design. Torque
values must be used as specified during reassem-
bly to mure proper retention of these parts.
7. Using a drift to align holes, replace control arm
shaft in the direction as shown in Figure
3C-3.
Torque hex nut to 33 lb.ft. Make certain that crown
of both plate washers shows outward.
To change caster, three washers are available
- one
with a
.12” thickness, one that is .36” thick, and one
.24” thick. Toincrease caster place one of the thin
washers at the front of the control arm shaft and one
of the thick washers at the rear.
To decrease caster
place one thick washer at the front of the control
arm shaft and one thin washer at the rear.
1. Position jack below front suspension cross mem-
ber and raise front end of car. 8. Remove spring compressor, and install front
wheel and torque wheel nuts to 72 ft. Ibs.
9. Recheck caster.ADJUSTING CASTER (OPEL
1900. MANTA)
2. Place jack stands below front frame side members
and remove front wheel on side which caster is to be
adjusted. 1. Jack up vehicle and remove front wheel on the side
on which caster is to be adjusted.
3. Install front spring compressor J-21689 and com-
press spring. See Figure
3C-2.
2. Support vehicle below both lower control arms.
See Figure
3C-4.
3. Unscrew hex nut from upper control arm shaft
and pull out shaft.
4. Adjust caster by replacing washers (A) (front) and

WHEELS AND TIRES3G- 55
WHEELS AND TIRES
CONTENTS
Subject
DESCRIPTION AND OPERATION: (Not Applicable)
DIAGNOSIS:
Car
RoughnessandVibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .AbnormalTireWear
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MAINTENANCE AND ADJUSTMENTS:
Demounting and Mounting Tubeless Tires
. . . . . . . . . . . . . .Wheel
andTireBalance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MAJOR REPAIR: (Not Applicable)
SPECIFICATIONS:
Specifications
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page No.
3G-55
3G-58
3G-6136-6236-62
DIAGNOSIS
CAR ROUGHNESS AND VIBRATIONinflation pressures and perform tire inspection, in-
cluding removal of any foreign material on tire tread
or wheel large enough to upset balance.
Possible Causes
To assist in the diagnosis and correction of some of
the more stubborn cases of tire vibration and rough-
ness conditions that may be encountered, the follow-
ing information is offered:Tire inflation pressure recommendations are very
important at all times and particularly so on all ride
complaints. Raising or lowering tire pressures to
“improve” mileage or traction should not be at-
tempted.
VIBRATION, or a quivering motion condition, no-
ticeable by feel through the steering column, steering
wheel, floor
p&n, or by hood and fender shake, usu-
ally originates from the front wheels and tires. Front
end vibration, when caused by unbalanced front
wheels, can be generally felt as steering wheel “nib-ble”.Next, road-test the car with the owner, if possible,
and have the owner explain the specific ride disturb-
ance.After road-testing, raise car on hoist and proceed to
isolate the offending tire/wheel assembly.
Reproducing the Disturbance
A vibration felt through the seats as a side-to-side
disturbance can usually be attributed to the rearIn an attempt to reproduce the disturbance ex-
wheels and tires.perienced in the ride, a wheel spinner can be used on
the front wheels of the car.
Both front and rear vibration can be noticed mainly
at highway speeds, usually over 60 mph.The rear wheels may be spun by placing car in
“Drive” with engine running.
ROUGHNESS, noticeable primarily at speeds be-
tween 40 and 65 mph, can be felt (and occasionally
heard), and is due to certain irregularities in the tire.
Roughness usually sets up a “trembling” feel or a
shuddering effect.When spinning rear wheels, never exceed a speedom-
eter speed of 35 mph with a standard rear axle assem-
bly, or 75 mph on one with a positive traction rear
axle. Excessive speeds may cause damage to the rear
axle assembly.
Road-Test With Owner
When a ride complaint is encountered, first checkJack up both rear wheels by placing the jack under
the differential housing. Spin one wheel and tire with
the opposite wheel held from rotating by holding the

3G- 581873 OPEL SERVICE MANUALTire Wear IrregularitiesAn additional cause of vibrations may sometimes be
tire wear irregularities. These can also produce noise
disturbances, and can be generally corrected by
rotating the tires, Figure
3G-6. Before proceeding
further, locate and correct the cause of the irregular
tire wear. See Figure
3G-7.Use the criss-cross method of rotation of tires only
when all four tires are equally worn. In some in-
stances, it may be necessary to put the truest running
assemblies (those with the lowest tolerances) on the
front of the car.
Wheel Nut Torque end Tightening SpecificationsDuring all wheel installations, it is important to use
the correct procedures for installing wheel nuts and
torquing them uniformly and in proper sequence.
This is important in order to avoid possible distor-
tion of the brake drum or disc, and to minimize
damage to lug and nut threads and wheel stud holes.
To assure uniform tightening of wheel lug nuts, the
following procedure is recommended:
1. Install wheel lug nuts in a criss-cross pattern and
tighten just enough to seat wheel against hub. This
assures proper piloting of the wheel on its hub.
2. Tighten lug nuts uniformly to proper torque of 65
Ib.ft. using criss-cross pattern.
An impact wrench should not be used, as uniform
torque control cannot be maintained.
Summary of Diagnosis end Correction of Tire and
Wheel Vibration1. Inflate all tires to recommended pressure and
road-test car with owner to define problem.
2. Spin front tire/wheel assemblies with wheel driv-
ing equipment. Rear wheels may be spun with tires
off the ground and with one wheel held at a time. The
offending tire may cause vibration that may be felt
by touching the bumper or fender. By process of
elimination, determine offending tire/wheel assem-
bly.
3. Check for tire/wheel unbalance. Balance, if neces-
sary.4. Check each tire/wheel assembly on the car for
radial runout on the tire tread. Wheel and tire assem-
blies exceeding
.050 inches may be considered as
offending assemblies. Offending tire/wheel assemblyshould be deflated and the tire repositioned (indexed)
180 degrees from original location.
5. After repositioning, rebalance tire/wheel assembly
(static and dynamic preferred).
6. Test drive and evaluate correction.
The following procedure should be used to determine
cause of roughness or vibration with car in operation
at various speeds:
I. Jack up all wheels having jack support rear end of
car at center of rear axle housing.
2. With transmission in “Drive”, run engine at vari-
ous car speeds to note speeds at which vibration or
roughness occurs.
3. Remove rear wheels and run engine again at the
critical speeds noted in step 2. If roughness is gone,
the condition is caused by unbalanced wheel and tire
assemblies.
4. If roughness still exists with rear wheels removed,
remove rear brake drums and repeat the running
test. Elimination of the roughness indicates out of
balance brake drums.
5. If roughness still exists with brake drums
removed, run engine with transmission in “Neutral”.
Elimination of the roughness indicates that propeller
shaft is out of balance. Continued roughness indi-
cates an out-of- balance engine.
ABNORMAL TIRE WEAR
General Operating ConditionsAssuming that there is no misalignment condition to
cause abnormal wear, the life of tires depends largely
upon car operation conditions and driving habits.
Tires wear at a much faster rate in some localities
than in others because of road and operating condi-
tions. Some types of roads are much more abrasive
than others. Tire wear is also dependent upon the
number of hills and mountains which the car must
go up and down, the severity of grades, the number
of starts and stops, driging speeds, the amount of rain
and snow, and prevailing temperatures. Tire
wear
increases rapidly with speed, temperature, and loadon tire. Tires used at low speeds, in cool climates, or
with light loads will have longer life than tires used
for high-speed driving in hot climates with heavy
loads.
Driving habits have a very important hearing on tire
life. A careful driver may obtain much greater mile-
age from a set of tires than would be obtained by a