suspension OPEL GT-R 1973 User Guide
Page 176 of 625
FRONT SUSPENSION3A- 9
8. Press ball stud out of lower control arm.Removal Opel 1900 - MantaBefore raising vehicle, install Hooks J-23697 on re-
spective vehicle side to cross member and upper con-
trol arm. See Figure 3A-7.
1. Raise car and support at rear of front frame rails.
2. Remove front wheel.
3. At the lower control arm ball joint, remove castle
nut cotter pin and slacken back nut so that the thread
can no longer be damaged.
4. With a suitable drift, detach ball joint from steer-
ing knuckle. With jack, lift up lower control arm,
unscrew castle nut and remove Hooks J-23697.
5. Unscrew upper control arm ball joint and suspend
front wheel hub and brake caliper in wheel house. Do
not turn upper control arm ball joint flange, as this
would result in a change of camber.
6. Remove defective lower control arm ball joint
using Tools J-9519 and Receiver J-23754.
Installation GT
CAUTION:
Fasteners are important attachingparts in
that they could affect the performance of
vitaI com-
ponents and systems, and/or could result in
ma&r
repair expense. They must be replaced with one of
the same part
numer or with an equivalent part if
replacement becomes necessary. Do not use a
re-
placement part of lesser quality or substitute design.
Torque values must be used as specified during reas-
sembly to assure proper retention of these parts.1. When pressing the ball joint in place, make certain
the locating notch in the lower rim of the ball joint
matches the alignment reference mark placed on the
lower control arm prior to removal. The notch in the
ball joint bottom plate, identifying the direction of
the elongated slot, must point towards the brake
drum backing plate. See Figure
3A-17. Alignment
must be within 2 degrees of lower control arm center-
line. If proper positioning of the ball joint is not
accomplished, the result is a limitation of the neces-
sary ball stud movement. If ball stud movement is
limited, an interference between the ball stud and
housing is created, and binding or even fracture may
occur. Replacement ball joints may or may not have
marking notch as shown in Figure
3A-20. If it does
not have a marking notch, the joint is completelysymetrical and may be installed in any position.
When pressing in ball joint do not press on bottom
plate, but on ball joint housing only.2. Install dust cap on lower ball joint and fill with
chassis lubricant. Attach dust cap retainer.
3. Press ball joint into steering knuckle. Use
J-9519-3 as installer and J-21690 as a supporting
sleeve.4. Install castle nut on ball joint stud and torque to
40
Ib.ft. Install new cotter pin.
5. Reconnect shock absorber to lower control arm
and torque to 30 lb.ft.
6. Remove spring compressor.
7. Install front wheel, and lower the car.
8. Always check caster and camber after ball joint
replacement.
Installation Opel 1900 - Manta
CAUTION:
Fasteners are important attachingparts in
that they could
aff’ect the performance of vital com-
ponents and systems, and/or could result in
ma&r
repair expense. They must be
rep/aced with one of
the same part number or with equivalent parts, if
rep/acement becomes necessary. Do not use a re-
p/acement part of lesser quality or substitute design.
Torque valves must be used as
specitied during reas-
sembIy to assure proper retention of these parts.1. Drive new ball joint into lower control arm using
Tools J-9519 as installer and J-23755 as a supporting
sleeve. Do not strike onto ball joint bottom.
The ball joint is maintenance-free. It is supplied as an
assembly only and cannot be disassembled further.
2. On new lower control arm ball joint, make sure
that the marking groove in the housing bottom in
alignment with the axis of the lower control arm.
Permissible deviation: minus 2 degrees to plus 2 de-
grees.This is required, to obtain the maximum freedom of
movement of the ball stud in the housing. See Figure
3A-18.3. Attach steering knuckle together with front wheel
hub and brake caliper to lower control arm ball joint.
Torque castle nut to 54
ft.lbs.4. Attach ball joint to upper control arm and torque
to 29
ft.lbs. Always use new self-locking nuts.
5. Install wheel and tighten nuts to a torque of 65
ft.lbs.6. Lower car and check caster and camber.
Page 178 of 625
FRONT SUSPENSION3A- 11UPPER CONTROL ARM SHAFT
INNER SLEEVE
OUTER SLEEVE
RUBBER DAMPENIN
GUIDE SLEEVE
ABSORBER SUPPOR
SHOCK ABSORBER SUPPORT
ON FRONT SUSPENSION
CROSS MEMBER
-TOOTHED WASHER
l-UPPER CONTROL ARM
RUBBER BUSHINGS
PLATE WASHER
Figure
3A-19 Upper Control Arm Shaft and Bushings
placement part of lesser quality or substitute design.
Torque
valves must be used as specified during reas-
semb/y to assure proper retention of these parts.1. On installation of the upper control arm, make
sure that damper bushing with the rubber shoulder
on both sides is always located in the rear.
2. Attach upper control arm to cross member and
torque to
40 lb.ft. Always use new self-locking hex
nut. The upper control arm must be tightened in
horizontal position only. This applies also to all other
attaching joints in connection with rubber damper
bushings in the control arms of the front suspension
so that the rubber parts under load are in an almost
twist-free condition. This position exists, if the hooks
J-23697 are used.
3. Attach ball joint to upper control arm and torque
to 29
lb.ft.4. Install wheel and torque nuts to 65
lb.ft. Lowercar.LOWER CONTROL ARM REMOVAL AND
INSTALLATION
Removal GT
1. Raise car and support at rear of front frame rails.
2. Remove front wheel.
3. Remove cotter pin from castle nut on ball joint
stud and back off castle nut two (2) turns. Hit ball
stud a sharp blow to break it loose. DO NOT
REMOVE NUT.
4. Install spring compressor (J-21689) and compress
spring until a distance of
3-l/8 inches is achieved
between spring compressor and lower spring leaf.
5. Disconnect and compress shock absorber.
6. Support rail of spring compressor with a jack.
Remove lower control arm from frame cross mem-
ber. Nuts may have to be removed with a punch. See
Figure 3A-20. Discard the lock nuts.
7. Remove lower ball joint stud nut. Slightly lower
Page 180 of 625
FRONT SUSPENSION3A- 13
6. Reconnect shock absorber to lower control arm
and torque to 30
Ib.ft.7. Remove spring compressor.
8. Install front wheel, and lower the car.
9. Check front end alignment.
Installation Opel 1900 Manta
CAUTION: Fasteners are important attachingparts in
that they could aff&
the-performance of vitaI com-
ponents and systems, and/or could
resu/t in major
repair expenses. They must be
repraced with one of
the same part number or with an
equivaknt part, ifreplacement becomes necessary. Do not use a re-
placement part of ksser quality or substitute design.
Torque values must be used as specified
dmitig reas-
sembIy to assure proper retention of these parts.1. Loosely attach lower control arm to front cross
member.
2. Properly seat spring between lower control arm
and cross member.
3. Raise jack and place lower control into position.
4. Attach lower control ball joint to steering knuckle
and torque nut to 54
Ib.ft.5. Tighten lower control arm to cross member bolt
to 43
lb.ft.6. Attach stabilizer bar to lower control arm and
torque to 87
lb.ft.7. Attach stabilizer bar to cross member to body
support.
8. Install shock absorber and torque lower attaching
nut and bolt to 30
lb.ft.9. Install nuts on upper shock absorber attaching
studs. Tighten nuts until a distance from top of nut
to stud is approximately
l/2 inch.
10. Install front wheels and tighten nuts to 65
lb.ft.11. Remove stands and lower car.
STEERING KNUCKLE REMOVAL AND
INSTALLATION
Removal GT1. Raise car and support with stands.
2. Remove wheel nuts. Remove wheel assembly.
Figure 3A-2 1 Caliper Attachment4. Remove spindle grease cap. Remove cotter pin
and spindle nut. Remove wheel hub with disc.
5. Install J-21689 spring compressor and compress
spring until 3-l/8” clearance is obtained between
spring compressor and lower spring leaf.
6. Remove upper ball joint using tie rod remover,
J-
21687.7. Remove shock absorber at lower attachment only.
8. Remove lower ball joint using J-21687 remover
and remove steering knuckle. Remove dust shield
from steering knuckle.
Removal Opel 1900. Manta1. Raise car and support with stands.
2. Detach brake caliper and steering arm from steer-
ing knuckle.
3. Remove castle nut cotter pin, unscrew nut and
pull steering knuckle off upper control arm ball joint.
4. Unscrew brake caliper and suspend it in wheel
house.5. Remove front wheel hub.
6. Unscrew steering arm and brake cover plate from
Page 182 of 625
FRONT SUSPENSION3A- 15
SHOCK ABSORBER REMOVAL ANDINSTALLATION
Removal
Opel 1900. Manta1. Raise car and support with stands.
2. Remove upper attaching nuts from shock ab-
sorber.3. Remove lower attaching nut, lockwasher, and
bolt.
4. Compress shock absorber and remove from car.
Removal GT1. Remove air cleaner. See Figure 3A-24.
Figure 3A-24 Removal of Air Cleaner
2. Remove plastic cover over shock absorber upper
attachment.
3. Raise car and support with stands.
4. Remove upper attaching nuts from shock ab-
sorber.5. Remove lower attaching nut, lockwasher, and
bolt.
6. Compress shock absorber and remove from car.
Installation Opel 1900. Manta1. Inspect shock absorber for damage and seal leaks.Always replace the upper and lower rubber grom-
mets when replacing a shock absorber.
2. Install the lower grommet retainer and grommets
on shock absorber. Compress shock absorber and
place in position.
3. Install lower attaching bolt and nut. Torque to 30
lb.ft.4. Install nuts on upper attaching studs. Tighten nuts
until distance from top of nut to stud is approxi-
mately
l/2 inch. See Figure 3A-25.5. Install plastic cover.
Installation GT1. Inspect shock absorber for damage and seal leaks.
Always replace the upper and lower rubber grom-
mets when replacing a shock absorber.
2. Install the lower grommet retainer and grommets
on shock absorber. Compress shock absorber and
place in position.
3. Install lower attaching bolt and nut. Torque to 30
lb. ft.
4. Install nuts on upper attaching studs. Tighten nuts
until distance from top of nut to stud is approxi-
mately
l/2 inch. See Figure 3A-25.5. Install plastic cover.
6. Install air cleaner.
FRONT SPRING REMOVAL AND INSTALLATION
Removal (GT)1. Raise car and support at rear of front frame rails
with stands.
2. Remove front wheels.
3. Remove cotter pin from castle nut on lower ball
joint studs and back off castle nut two (2) turns. Hit
ball stud a sharp blow to break it loose. Do not
remove nut.4. Install J-21689 spring compressor and compress
the spring until 3-l/8” clearance is obtained between
spring and compressor.
5. Disconnect both shock absorbers at their lower
attachment. Compress both shock absorbers.
6. Support the rail of J-21689 Spring Compressor
with a jack. Remove lower control arm to cross
member attaching nuts and bolts.
Page 184 of 625
FRONT SUSPENSION3A- 17Torque values must be used as specified during reas-
sembly to assure proper retention of these parts.1. Attach lower control arm to front spring eye.
Torque bolts to 18
lb.ft.2. Install spring compressor on spring and compress
spring to appropriate length.
3. Raise jack with spring compressor, spring and
control arm assembly into position under the car.
4. Install lower ball joints and torque nuts to 54
Ib.ft.Install new cotter pin.
5. Attach lower control arms to frame cross member
using new lock nuts.
6. Attach both shock absorbers. Torque bolts to 30
lb.ft.7. Remove spring compressor.
8. Install front wheels.
On replacement of the damper bushings on the front
springs, only the one-part damper bushing is in-
stalled for either the two-leaf or three-leaf spring.
For proper location of the marking lugs, see Figure3A-26.
Installation (Opel 1900. Manta)
CAUTION: Fasteners are important attachingparts in
that they
co&d affect the performance of vital com-
ponents and systems, and/or could result in major
repair expense. They must be replaced with one of
the same part number or with an equivalent part, if
replacement becomes necessary. Do not use a re-
placement part of
lesser quality or substitute design.
Torque values must be used as specified
during reas-
sembly to assure proper retention of these parts.1. Properly seat spring between lower control arm
and cross member.
2. Raise jack and place lower control into position.CROSS SECTION
SA-26Fig. 3A-26 Front Spring Damper Bushing.
3. Attach lower control ball joint to steering knuckle
and torque nut to 54
lb.ft.4. Tighten lower control arm to cross member bolt
to 43 lb.ft.
5. Attach stabilizer bar to cross member to body
support.
6. Install shock absorber and torque lower attaching
nut and bolt to 30
lb.ft.7. Install nuts on upper shock absorber attaching
studs. Tighten nuts until a distance from top of nut
to stud is approximately
l/2 inch.
8. Install front wheels and tighten nuts to 65
lb.ft.9. Remove stands and lower car.
SPECIFICATIONSBOLT TORQUE AND FRONT END ALIGNMENT
Page 185 of 625
3A- 161973 OPEL SERVICE MANUAL
SPECIFICATIONS
Torque Specifications
Use a reliable torque wrench to tighten all parts listed to insure proper
tightness without straining or distorting parts. These specifications are for
clean and lightly-lubricated threads only; dry or dirty threads produce in-
creased friction which prevents accurate maasurement of tightness.
LocationFront Suspension Crossmember to Front Frame
Clamp, Steering Mast to Steering Mast Flange
(GT)
........................................................................................
Clamp, Steering Mast to Steering Mast Flange(1900
-Manta)..................................................................
Clamp,UpperUniversalJoint(GT)..................................Clamp, Lower Universal Joint (GT)
..................................
WheelNuts............................................................................Lower Control Arm Shaft to Lower Control Arm
..........Lower Control Arm Ball Joint to Steering Knuckle
......Upper Control Arm Ball Joint to Steering Knuckle
(GT)........................................................................................Upper Control Arm Ball Joint to Steering Knuckle
(1 900 Manta)
..................................................................Upper Control Arm Ball Joint to Upper Control Arm
ShockAbsorbertoLowerControlArm..........................Steering Arm to Steering Knuckle (1900
- Manta)......
Brake Backing Plate or Brake Disc Shield andSteering Arm to Steering Knuckle
(GTJ
Hex Head Bolt M 10......Hex Head Bolt M 8
......
Brake Backing Plate to Steering Knuckle(1900 Manta)
..................................................................
Brake Caliper to Steering Knuckle.................................
Lower Control Arm to Front Spring Eye (GT)................
Brake Disc to Front Wheel Hub........................................Upper Control Arm to Crossmember (1900
- MantajLower Control Arm to Crossmember (1900
- Manta)
Steering Gear Housing to Front Suspension
Crossmember (GT)
............................................................
Steering Gear Housing to Front SuspensionCrossmember (1900
- Manta)........................................Stabilizer Bar to Lower Control Arm
(Opel 1900
- Manta)........................................................Tie Rod Clamp Bolts
(GTJ....................................................
CastleNut,TieRodtoSteeringArm..............................Upper Control Arm Shaft to Shock Absorber Support
and Upper Control Arm (GT)
..........................................
CrossMember to
BodySupport Attachment................
FrontSuspensionAssemblytoFrame............................Front End Alignment Specifications
Torque
Lb.Ft.36
1522
14
22
6540
5429
ii30
5847
18
58
72
1836
40
43
1830
87
:i33
58
47ModelCaster’
Camber”1900‘3
l/2-6 l/2GT
3+1-:%+*Permissible deviation from left to right wheel
- Max. 1’.
Toe-In”Min.-Max.
l/8-3/ 16
l/32-1/8Outer Wheel
When Inner
Wheel at 20
19
l/418
l/2
Page 189 of 625
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-
Page 190 of 625
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
Page 193 of 625
3C-26 1973 OPEL SERVICE MANUAL
1. Loosen lock nut of left and right tie rod and
slacken back nut.
2. Remove hose clamp for rubber bellows attach-
ment from respective axial joint and adjust toe-in by
turning axial joint. When doing this, observe that the
rubber bellows, having a tight seat on thejoint, is not
twisted. If necessary, lubricate seat of bellows and
hold back bellows when turning. See Figure 3C-7.Figure
3C-7 Adjusting Toe-In Opel 1900 Manta
3. Toe-in should be l/S”
- 3/16”.
4. Torque lock nut of left and right tie rod to 47
ft.lbs.5. Attach respective rubber bellows with hose clamp,
making sure that clamp bolt points towards the
front. The rubber bellows must not be twisted, i.e.,
SpecificationsFRONT END ALIGNMENTthe individual grooves of bellows must be in vertical
position.
6. After adjustment, turn steering several times to the
left and right to determine if a proper attachment of
both rubber bellows to the steering gear housing is
warranted.
CHECKING THEORETICAL KING PIN
INCLINATION
When checking theoretical king pin inclination, car
must be on a level surface, both transversely and fore
and aft, must have trim heights within limits, and
must be at curb load.
With camber known to be within specitied limits,
theoretical king pin inclination should check to 8.5
degrees for Opel 1900
- Manta, and 6 degrees for GT.
If camber is incorrect beyond limits of adjustment
and theoretical king pin inclination is correct, or
nearly so, a bent steering knuckle is indicated.
There is no adjustment for theoretical king pin incli-
nation as this factor depends on the accuracy of the
fronts suspension parts. Distorted parts should be re-
placed with new parts.
The practice of heating and bending front suspension
parts to correct errors must be avoided as this may
produce soft spots in the metal in which fatigue and
breakage may develop in service.
MODELCASTER
’CAMBER ’TOE-INOUTER WHEEL
MIN.. MAX.WHEN INNER
WHEEL AT 20
’1900‘3
l/2-61/2-1?1/2I/% - 3/1619 l/4GT3+1
1+1/2l/32 - l/818 l/2* Permissable deviation from left to right wheel
- maximum 1”.
Page 196 of 625
STEERING GEAR ASSEMBLY30-292. Loosen clamp securing flexible coupling to steer-
ing shaft.
4. Remove stop bolt (see Figure 3D-4) from under-
side of steering column (secures steering shaft bush-
ing to mast jacket), and pull steering wheel rearward
approximately three inches.
Figure
3D-4 Stop Bolt
4. Remove cotter pin located on left and right tie rod
ends and unscrew nut.
5. Using remover J-21687, press ball studs out of
steering arms (see Figure
3D-5).
IJ-21 68’Figure 3D-5 Removing Ball Stud6. Remove four attaching bolts securing steering gear
to front suspension cross member (see Figure 3D-6)
and lift off steering gear assembly and tie rods.
Figure
3D-6 Steering Gear Assembly Attaching Bolts
Removal (Opel 1900. Manta)1. Remove splash shield from lower deflector pa:
and both side members. See Figure
3D-7.nel
Figure
3D-7 Removing Splash Shield
2. Remove clamp bolt securing flexible coupling to
steering shaft. See Figure
3D-8.