1973 OPEL GT-R service

7C- 481973 OPEL SERVICE MANUAL
INPUT SUNRING
GEAR ASSY.GEARPLANETARY
CARRIERASSY.REACTION SUNtow
GEAR 8 DRUMBAND
Figure 7C-25Planetary Gears
The planetary pinion shafts which support the plane-
tary pinions are secured to the planetary carrier by
means of a lock plate at the rear of the planetary
carrier preventing the pinion shafts from rotating or
working loose. The lock plate is secured to the car-
rier by screws.
The planetary carrier is welded to the output shaft,
therefore, the directional movement of the carrier
delivers the transmission’s torque to the output shaft.
The governor hub is splined to, and driven by, the
output shaft. See Figure 7C-26. A governor body is
bolted to the governor hub. The speedometer drive
gear is also driven by the output shaft, and is secured
to the shaft by a retaining clip.
MECHANICAL OPERATIONThe following information describes how engine
torque is transmitted through the Opel Three Speed
automatic transmission for each selected position on
the quadrant. In every case, with the engine running,
torque is transmitted via the flex plate and converter7G25
cover to
tht? pump member of the converter. The
converter is always tilled with oil from the transmis-
sion’s oil pump, and the converter pump member
transmits the torque through oil to the driven mem-
ber of the converter. Power to the transmission is
then transmitted via the input shaft and third clutch
drum. See Figures
7C-48 through 7C-52.
HYDRAULIC CONTROL UNITS AND VALVESPreviously, the mechanical aspects of the transmis-
sion operation have been described, including refer-
ence to various clutches and the low band being
applied. The following describes, in detail, the hy-
draulic system that applies the clutches and band,
and which controls the manually selected and auto-
matic shifts.
A hydraulic pressure system requires a source of
clean hydraulic fluid and a pump to pressurize the
fluid. Opel Three Speed Automatic transmission uses
a gear type pump which draws oil through a screen
located in the sump. See Figure
7C-29. Since the
pump drive gear is keyed to the converter pump hub,
it turns whenever the engine is operating and turns
the driven gear, which causes the oil to be lifted from

712.501973 OPEL SERVICE MANUAL
3. Detent pressure regulator valve.
4. 1 - 2 Accumulator valve.
5. Governor.
B. Selector valves (manually and hydraulically con-
trolled).
I. Manual valve.
2. Detent valve.
3. 1
- 2 Shift valve.
4. 2
- 3 Shift valve.
5. 3
- 2 Downshift control valve.
6. Manual low and reverse control valve.
7. Boost control valve.
C. Timing Valves.
1. Low speed downshift timing valve.
2. High speed downshift timing valve.
3. Second clutch orifice valve.
D. Accumulators.
1. 1
- 2 Accumulator.
2. Low servo piston.
Main Pressure Regulator ValveOil pressure from the pump is delivered to the “line”
port of the main regulator valve. See Figure
7C-30.The port is connected through a damping orifice, to
the regulator port at the end of the regulator valve.
As the pressure in this port increases, it moves the
valve against the spring force until the second spool
of the. valve just opens to the “line” port. This per-
mits the pump pressure to be by- passed into the
pump suction passage. Therefore, the valve will regu-
late at
a’ fixed minimum pressure as determined by
the spring force, and all excess pump delivery will be
by-passed back into the pump suction passage.
In moving from the “bottomed” to the regulating
position, the valve also opens line pressure to the
converter feed passage. This oil is directed to and
through the
cow&x, through the oil cooler, to the
gear box lubrication system, then back to the sump.
In order to provide the required capacity in the band
and clutches, it is desirable to have a variable line
pressure that will increase with engine torque. This
PRESSURE’REGULATORY7c30Figure 7C-30 Pressure Regulator Valve
is accomplished by introducing a “modulator” pres-
sure on the end of the boost valve. The force of the
boost valve acts against the end of the regulator valve
and increases the line pressure above the base pres-
sure as established by the spring force. By introduc-
ing line pressure to the stepped area between the
spools of the boost valve, an additional pressure in-
crease over and above that described above is ob-
tained.
The regulated line pressure is then fed to:
Manual valve.
Modulator valve
Detent pressure regulator valve
Modulator Valve and Vacuum ModulatorLine pressure is directed to the second port of the
modulator valve. See Figure
7C-31. This pressure
passes between the spools of the valve and into the
modulator port. The modulator port is connected to
the regulating port at the end of the valve through a
damping orifice. As the pressure in the regulating
port incieases, it moves the valve outward against
the spring force of the modulator assembly until the
end spool just closes the line port. If excess pressure
has built up in the regulating port the valve will
continue to move till the second spool just opens to
the exhaust port. In other words, the valve tends to
regulate between the line and exhaust ports.
Even though the modulator spring force may be con-
stant, thereby causing the modulator valve to regu-
late at a fixed pressure, the pressure requirements

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.

7C- 541973 OPEL SERVICE MANUAL
Figure 7C-38 1 2 Shift Valve
To prevent a “hunting” condition of the shift valve,
modulator pressure supply to the second spool of
control valve is cut off as the shift valve opens line
pressure to the second clutch. The oil in this pocket
is exhausted out through the detent passage. An ad-
ditional force keeping the valve in an “upshifted”
position is obtained by line pressure acting on the
larger diameter second spool of the shift valve. Be-
cause of this, even though the governor pressure
might be maintained at a constant pressure after the
valve upshifts, a higher modulator pressure is re-
quired to cause the valve to downshift.
If the accelerator is depressed to the point where the
detent spring force is felt, the vacuum will drop and
the modulator pressure will increase. If the spring
force plus the modulator pressure acting against the
end spool of the shift control valve is great enough
to overcome the governor and line pressure acting on
the shift valve, a “part throttle” forced downshift
will occur. If not, the transmission will remain in the
higher gear.
If the accelerator is depressed through the detent, the
detent valve supplies detent regulator pressure to all
three spools of the shift control valve, a higher down-
shifting force is obtained as compared to the part
throttle condition. Because of this, a “through
detent” forced downshift can be obtained at a speed
higher than for the “part throttle” condition. How-
ever, there is still a limiting speed at which a
“through detent” forced downshift will occur.
If the selector lever is placed in “Manual Low”, line
pressure is supplied directly to the spring pocket
between the valves. Since line pressure can never be
less than governor pressure, the force established by
line pressure on the shift valve plus the spring forcewill move the shift valve to a downshifted position
regardless of car speed.
2 3
,Shift Valve and 3 - 2 Control Valve
The function and operation of the 2 3 Shift and
Shift Control Valves is the same as for the
I 2 valve
except as described below. See Figure
7C-39.The downshifted position establishes “second” gear,
and the upshifted position establishes “third” or
“high” gear.
~ZND CLUTCH*
-I.Figure
7C-39 2 3 Shift Valve and 3 2 Control Valve
Modulator pressure is supplied to the end spool of
the 2
- 3 control valve through the 3 - 2 control valve.
When the shift valve moves to the upshifted position,
line pressure is introduced to the third clutch circuit.
The third clutch circuit also directs pressure to the
end spool of the 3
- 2 control valve.
At light throttle conditions, third clutch pressure
acting on the end of the 3
- 2 control valve moves the
valve against the spring and the force established by
the modulator pressure. This exhausts the modulator
pressure from behind the end spool of the 2
- 3
control valve and the spring is the only remaining
force acting on the shift valve to produce a down-
shift. In this condition, it is not possible to obtain a
“part throttle” forced downshift.
If the accelerator is depressed far enough to cause a
substantial drop in vacuum, the increased modulator
pressure on the 3
- 2 control valve plus the spring will
overc,ome the force of the third clutch pressure. This
feeds modulator pressure back to the 2
- 3 control
valve and a “part throttle” forced downshift will
occur. As with the 1 2 shift valve, there is a limiting
speed at which this can occur.
When the selector lever is placed in “Second”, line
pressure is directed to the spring pocket between the
2
- 3 Shift and Shift Control Valves and the shift

7C- 561973 OPEL SERVICE MANUALMODULATORFigure
7C-42 Low Speed Downshift Timing Valve
During a “coast” condition, the vacuum is high and
the modulator pressure is zero. The spring holds the
timing valve in a bottomed position and the servo
release pressure is exhausted through a restricting
orifice, thus delaying the apply of the servo.
During a “power on” 3-2 downshift at lower car
speeds, the servo must be applied rapidly. During
such a shift, the vacuum will be somewhat lower and
the resulting modulator pressure will force the valve
over against the spring. This provides an unrestricted
passage for servo release, thus permitting rapid apply
of the servo.
High Speed Downshift Timing Valve
When a 3-2 downshift is “forced” at high car speeds,
the application of the band must be delayed. Servo
apply pressure is directed through the high speed
downshift timing valve. See Figure
7C-43.The timing valve is held in a bottomed position by
the spring at lower car speeds. This permits an unre-
stricted
flow for servo apply. At higher car speeds,
approximately 25 to 35 MPH, (depending on axle
ratio and engine), governor pressure forces the valve
over against the spring. This closes off the direct feed
to servo apply and the feed is controlled by a fixed
orifice.While it may outwardly appear that the functions of
the two downshift timing valves are contradictory,
whether or not the application of the band is delayed
during a 3-2 downshift is a combined function of car
speed and throttle position.
--Figure
7C-43 High Speed Downshift Timing Valve
Second Clutch Orifice Valve
For reasons of shift timing, it is necessary to have
different restricting orifice sizes for the feed and ex-
haust of the second clutch. This is accomplished by
introducing a “one way” ball check in the second
clutch circuit. See Figure
7C-44.2ND CLUTCH
I?C-44
Figure
7C-44 Second Clutch Orifice Valve
When the second clutch is being applied, the apply
pressure seats the ball and the feed is directed
through a single orifice. During the release of the
clutch, the ball is unseated and the clutch can ex-
haust at a faster rate through the two orifices.

7c. 581973 OPEL SERVICE MANUAL
a. NEUTRAL & PARK
- ENGINE RUNNING
Neutral
- Engine Running
Reverse Clutch. Released
Second Clutch. Released
Sprag
- LockedThird Clutch
- Released
Low Band .
.ReleasedIn neutral, the low band and all clutches are released. With this condition, no member of the planetary gear set is
held and there is no reaction member. All gears are free to rotate around their own axis and no torque is trans-
mitted to the planet carrier assembly and output shaft.
Park
- Engine Running
The same power flow conditions in the neutral position are in effect in the park position. Additionally, mechan-
ical linkage actuates a parking pawl which engages with the
splines in the periphery of the governor assembly.
Since the governor assembly is splinad to the output shaft, the parking pawl holds the output shaft locked to the
extension, preventing the vehicle from rolling.7ci48
Figure 7C-48 Neutral and Park Engine Running

7C- 601973 OPEL SERVICE MANUAL
c. DRIVE RANGE. SECONO GEAROrive Range . Second Gear
Reverse Clutch - Released
Second Clutch -Applied
Sprag
- Overrunning
In Drive Range. Second Gear, the low band and second clutch are applied.Third Clutch
- Released
Low Band -Applied
The input shaft drives the third clutch drum and the second clutch composition plates. When the second clutch
piston is applied, the rotating second clutch composition plates are locked
w the second clutch steel plates. Since
the second clutch drum is now rotating in a clockwise direction, the ring gear is driven clockwise. As described in
“Principles of Operation”, the carrier is driven in a clockwise direction. The long planet pinions also drive the
short planet pinions, which drive the input sun gear clockwise, causing the sprag assembly to overrun. The ratio
is 1.48:1.
second Range
In Second Range, the Power flow is exactly the seme as drive range - second gear.7c50
Figure
7C-50 Drive Range - Second Gear

712.641973 OPEL SERVICE MANUALHYDRAULIC OPERATION
‘Irn