The torque and engine speed are converted accord-
ing to the lever ratios and the ratio of the number of
teeth on the driven gears to that on the drive gears,
and is referred to as the gear ratio. The overall ratio
of a number of planetary gear sets connected in
series is obtained by multiplying the partial ratios.
DISASSEMBLY
(1) Remove upper two visible Teflon rings (1) (Fig.
201) from output shaft.
(2) Remove retaining ring (11), shim (10), thrust
needle bearing (9) and thrust washer (8) from output
shaft.
(3) Remove clutch K3 (7).
(4) Remove rear tubular shaft/freewheeling clutch
F2 (6) (Fig. 201) from output shaft.
(5) Remove rear gear set (5) with integrated tubu-
lar shaft of center gear set from output shaft.
(6) Remove thrust washer (4).
ASSEMBLY
(1) Mount thrust washer (4) (Fig. 202) with the
collar pointing towards the planet carrier.
(2) Mount rear gear set (5) with integrated tubular
shaft of the center gear set on output shaft.
(3) Using grease, install lower three Teflon rings
(1) (Fig. 202) in the groove so that the joint stays
together
(4) Put rear tubular shaft/freewheeling clutch F2
(6) onto output shaft.
(5) Install clutch K3 (7).
(6) Mount retaining ring, shim, thrust needle bear-
ing and thrust washer (8 - 11) (Fig. 202).
(7) Using grease, insert the upper two Teflon rings
(1) in the groove so that the joint remains together.
Fig. 201 Output Shaft with Center and Rear Planetary Geartrain
1 - TEFLON RINGS 7 - DRIVING CLUTCH K3
2 - OUTPUT SHAFT WITH CENTER PLANETARY CARRIER 8 - THRUST WASHER
3 - NEEDLE BEARING 9 - AXIAL NEEDLE BEARING
4 - THRUST WASHER 10 - SHIM
5 - REAR PLANETARY GEAR SET 11 - RETAINING RING
6 - REAR HOLLOW SHAFT/FREEWHEELING CLUTCH F2
VAAUTOMATIC TRANSMISSION - NAG1 21 - 131
PLANETARY GEARTRAIN (Continued)
(8) Inspect axial play (Fig. 203) between shim (10)
and retaining ring (11). Check axial play9S9between
shim (10) and retaining ring (1) using a feeler gauge.
Clearance should be 0.15-0.6 mm (0.006-0.024 in.).
Shims are available in thicknesses of 3.0 mm (0.118
in.), 3.4 mm (0.134 in.), and 3.7 mm (0.146 in.).
Adjust as necessary
NOTE: During the test, apply a contact force by
hand to K3 in the direction of the arrow.
SHIFT MECHANISM
DESCRIPTION
The automatic transmission is operated with the
help of a shift lever assembly (SLA) located in the
center console. There are four positions to which the
selection lever can be shifted: P, R, N, D. In addition,
the selector lever can be moved sideways (+/-) in posi-
tion9D9to adjust the shift range.
All selector lever positions, as well as selected shift
ranges in position9D9, are identified by the SLA. The
information is then sent to the transmission control
module (TCM) via a hardwire connection. At the
same time, the selector lever positions9P9,9R9,9N9
and9D9are transmitted by a shift cable to the selec-
tor shaft in the transmission.
The SLA is comprised of the following functions:²Key lock:Depending on the selector lever posi-
tion, the ignition lock is locked/unlocked, i.e., the
ignition key can be removed only if the selector lever
is in position9P9. A park lock cable is used to perform
this function.
²Park lock:The selector lever is not released
from postion9P9until the brake pedal has been
applied and the ignition key is in driving position.
Shift lock is controlled by the brake light switch in
conjunction with a locking solenoid in the SLA. As
soon as the brake pedal is applied firmly, the locking
solenoid is retracted to unlock the selector lever. If
the selector lever cannot be moved out of position9P9
due to a malfunction, the shift lock function can be
overriden (see operator's manual).
²Reverse inhibitor:As soon as the vehicle
speed exceeds approx. 4 mph, it is no longer possible
to move the selector lever from position9N9to posi-
tion9R9.
OPERATION
With the selector lever in position9D9, the trans-
mission control module (TCM) automatically shifts
the gears that are best-suited to the current operat-
ing situation. This means that shifting of gears is
continuously adjusted to current driving and operat-
ing conditions in line with the selected shift range
and the accelerator pedal position. Starting off is
always performed in 1st gear.
The selector lever positions are determined by the
slider position of a potentiometer in the shift lever
assembly (SLA). The shift pattern diagram (position
display) and the program selector are illuminated by
the LEDs.
The current selector lever position or, if the shift
range has been limited, the current shift range is
indicated in the LCD display in the instrument clus-
ter.
The permissible shifter positions and transmission
operating ranges are:
²P = Parking lock and engine starting.
²R = Reverse.
²N = Neutral and engine starting (no power is
transmitted to the axles).
²D = The shift range includes all forward gears.
²4= Shift range is limited to gears 1 to 4.
²3= Shift range is limited to gears 1 to 3.
²2= Shift range is limited to gears 1 to 2.
²1= Shift range is limited to the 1st gear.
The shift range can be adjusted to the current
operating conditions by tipping the selector lever to
the left-hand side (9-9) or the right-hand side (9+9)
when in position9D9. If the shift range is limited, the
display in the instrument cluster indicates the
selected shift range and not the currently engaged
gear.
Fig. 203 Check Center and Rear Planetary End-Play
1 - DRIVING CLUTCH K3
2 - THRUST WASHER
3 - SHIM
4 - AXIAL NEEDLE BEARING
5 - RETAINING RING
6 - OUTPUT SHAFT WITH CENTER PLANETARY CARRIER
VAAUTOMATIC TRANSMISSION - NAG1 21 - 133
PLANETARY GEARTRAIN (Continued)
Tipping the shift lever will have the following
results:
²Tipping the selector lever toward(-(one
time after another:The shift range is reduced in
descending sequence by one gear each time, i.e., from
D-4-3-2-1.Iftheselected limitation of the shift
range would result in a downshift causing excessive
engine speed, the shifting is not executed and the
engaged gear as well as the shift range remain
unchanged. This is to prevent the engine from over-
speeding. Engine retardation is low with the selector
lever in position9D9. To make use of the full braking
power of the engine,9manual9downshifting by tip-
ping the lever towards the left-hand side is recom-
mended. If this has been done, subsequent upshifting
must be carried out manually as well.
²Tipping the selector lever toward(-(and
holding it in this position:The currently engaged
gear in range9D9is indicated in the instrument clus-
ter display and the shift range is limited to this gear.
²Tipping the selector lever toward(+(one
time after another:The shift range is increased by
one gear each time and the increased shift range is
displayed in the instrument cluster; possibly, the
transmission upshifts to a faster gear.
²Tipping the selector lever toward(+(sev-
eral times:The shift range is increased by one gear
each time the lever is tipped until the shift range
ends up in9D9.
²Tipping the selector lever toward(+(and
holding it in this position:The shift range is
extended immediately to9D9, shift ranges are indi-
cated in ascending sequence; possibly, the transmis-
sion upshifts to a faster gear due to the extension of
the shift range.
REMOVAL
(1) Move selector lever to position9D9.
(2) Remove top section (3) (Fig. 204) of the center
section of instrument panel.
(3) Remove bottom section (2) (Fig. 205) of the cen-
ter section of instrument panel.
(4) Disconnect the park lock cable coupling (1)
(Fig. 206) from the shift lever assembly (SLA). Press
locking tab (2) together and push coupling (1) against
the spring force into the SLA, twist through 90É
(right or left) and pull off.
(5) Disconnect connector plug (5) from SLA. When
disconnecting plug, press together at points shown
(arrows).
(6) Pry ball socket (4) of transmission shift cable
off ball knob at the SLA. Use a suitable slotted
screwdriver.
Fig. 204 Remove Top Section Of Center Instrument
Panel
1 - SHIFT LEVER ASSEMBLY FRAME TRIM
2 - STORAGE COMPARTMENT
3 - TOP CENTER PART OF INSTRUMENT PANEL
4 - SCREW
5 - PLUG CONNECTIONS
6 - ASHTRAY
Fig. 205 Remove Bottom Section Of Center
Instrument Panel
1 - SCREW
2 - BOTTOM CENTER PART OF INSTRUMENT PANEL
21 - 134 AUTOMATIC TRANSMISSION - NAG1VA
SHIFT MECHANISM (Continued)
OPERATION - TRANSMISSION TEMPERATURE
SENSOR
The temperature of the transmission oil has a con-
siderable effect on the shifting time and therefore the
shift quality. By measuring the oil temperature, shift
operations can be optimized in all temperature
ranges. The transmission oil temperature sensor (1)
(Fig. 222) is switched in series with the park/neutral
contact. The temperature signal is transferred to the
TCM only when the dry-reed contact of the park/neu-
tral contact is closed in REVERSE or a forward gear
position.Refer to the Transmission Temperature Sensor
Specifications table (Fig. 223) for the relationship
between transmission temperature, sensor voltage,
and sensor resistance.
TORQUE CONVERTER
DESCRIPTION
The torque converter (Fig. 224) is a hydraulic
device that couples the engine crankshaft to the
transmission. The torque converter consists of an
outer shell with an internal turbine, a stator, an
overrunning clutch, an impeller and an electronically
applied converter clutch. The converter clutch pro-
vides reduced engine speed and greater fuel economy
when engaged. Clutch engagement also provides
reduced transmission fluid temperatures. The con-
verter clutch engages in third gear. The torque con-
verter hub drives the transmission oil (fluid) pump.
The torque converter is a sealed, welded unit that
is not repairable and is serviced as an assembly.
CAUTION: The torque converter must be replaced if
a transmission failure resulted in large amounts of
metal or fiber contamination in the fluid.
Fig. 220 Transmission Temperature Sensor
1 - TRANSMISSION TEMPERATURE SENSOR
Fig. 221 Park/Neutral Contact
1 - SHELL OF ELECTRIC CONTROL MODULE
2 - PLUNGER
3 - PERMANENT MAGNET
4 - DRY-REED CONTACT
Fig. 222 Transmission Temperature Sensor
1 - TRANSMISSION TEMPERATURE SENSOR
VAAUTOMATIC TRANSMISSION - NAG1 21 - 141
TEMPERATURE SENSOR/PARK-NEUTRAL CONTACT (Continued)
IMPELLER
The impeller (Fig. 225) is an integral part of the
converter housing. The impeller consists of curved
blades placed radially along the inside of the housing
on the transmission side of the converter. As the con-
verter housing is rotated by the engine, so is the
impeller, because they are one and the same and are
the driving members of the system.
TURBINE
The turbine (Fig. 226) is the output, or driven,
member of the converter. The turbine is mounted
within the housing opposite the impeller, but is not
attached to the housing. The input shaft is inserted
through the center of the impeller and splined into
the turbine. The design of the turbine is similar to
the impeller, except the blades of the turbine are
curved in the opposite direction.
STATOR
The stator assembly (Fig. 227) is mounted on a sta-
tionary shaft which is an integral part of the oil
pump. The stator is located between the impeller and
turbine within the torque converter case (Fig. 228).
The stator contains a freewheeling clutch, which
allows the stator to rotate only in a clockwise direc-
tion. When the stator is locked against the freewheel-
ing clutch, the torque multiplication feature of the
torque converter is operational.Fig. 223 Transmission Temperature Sensor
Specifications
Fig. 224 Torque Converter
1 - TURBINE
2 - IMPELLER
3-STATOR
4 - INPUT SHAFT
5 - STATOR SHAFT
21 - 142 AUTOMATIC TRANSMISSION - NAG1VA
TORQUE CONVERTER (Continued)
TORQUE CONVERTER CLUTCH (TCC)
The TCC (Fig. 229) was installed to improve the
efficiency of the torque converter that is lost to the
slippage of the fluid coupling. Although the fluid cou-
pling provides smooth, shock-free power transfer, it is
natural for all fluid couplings to slip. If the impeller
and turbine were mechanically locked together, a
zero slippage condition could be obtained. A hydraulic
piston with friction material was added to the tur-
bine assembly to provide this mechanical lock-up.
In order to reduce heat build-up in the transmis-
sion and buffer the powertrain against torsional
vibrations, the TCM can duty cycle the torque con-
verter lock-up solenoid to achieve a smooth applica-
tion of the torque converter clutch. This function,
referred to as Electronically Modulated Converter
Clutch (EMCC) can occur at various times depending
on the following variables:²Shift lever position
²Current gear range
²Transmission fluid temperature
²Engine coolant temperature
²Input speed
²Throttle angle
²Engine speed
OPERATION
The converter impeller (driving member), which is
integral to the converter housing and bolted to the
engine drive plate, rotates at engine speed. The con-
verter turbine (driven member), which reacts from
fluid pressure generated by the impeller, rotates and
turns the transmission input shaft.
Fig. 225 Impeller
1 - ENGINE FLEXPLATE 4 - ENGINE ROTATION
2 - OIL FLOW FROM IMPELLER SECTION INTO TURBINE
SECTION5 - ENGINE ROTATION
3 - IMPELLER VANES AND COVER ARE INTEGRAL
VAAUTOMATIC TRANSMISSION - NAG1 21 - 143
TORQUE CONVERTER (Continued)
TURBINE
As the fluid that was put into motion by the impel-
ler blades strikes the blades of the turbine, some of
the energy and rotational force is transferred into the
turbine and the input shaft. This causes both of them
(turbine and input shaft) to rotate in a clockwise
direction following the impeller. As the fluid is leav-
ing the trailing edges of the turbine's blades it con-
tinues in a ªhinderingº direction back toward the
impeller. If the fluid is not redirected before it strikes
the impeller, it will strike the impeller in such a
direction that it would tend to slow it down.
Fig. 226 Turbine
1 - TURBINE VANE 4 - PORTION OF TORQUE CONVERTER COVER
2 - ENGINE ROTATION 5 - ENGINE ROTATION
3 - INPUT SHAFT 6 - OIL FLOW WITHIN TURBINE SECTION
Fig. 227 Stator Components
1 - CAM (OUTER RACE)
2 - ROLLER
3 - SPRING
4 - INNER RACE
21 - 144 AUTOMATIC TRANSMISSION - NAG1VA
TORQUE CONVERTER (Continued)
STATOR
Torque multiplication is achieved by locking the
stator's over-running clutch to its shaft (Fig. 230).
Under stall conditions (the turbine is stationary), the
oil leaving the turbine blades strikes the face of the
stator blades and tries to rotate them in a counter-
clockwise direction. When this happens the over-run-
ning clutch of the stator locks and holds the stator
from rotating. With the stator locked, the oil strikes
the stator blades and is redirected into a ªhelpingº
direction before it enters the impeller. This circula-
tion of oil from impeller to turbine, turbine to stator,
and stator to impeller, can produce a maximum
torque multiplication of about 2.0:1. As the turbine
begins to match the speed of the impeller, the fluid
that was hitting the stator in such as way as to
cause it to lock-up is no longer doing so. In this con-
dition of operation, the stator begins to free wheel
and the converter acts as a fluid coupling.
Fig. 228 Stator Location
1-STATOR
2 - IMPELLER
3 - FLUID FLOW
4 - TURBINEFig. 229 Torque Converter Lock-up Clutch
1 - TURBINE
2 - IMPELLER
3-STATOR
4 - INPUT SHAFT
5 - STATOR SHAFT
6 - PISTON
7 - COVER SHELL
8 - INTERNALLY TOOTHED DISC CARRIER
9 - CLUTCH PLATE SET
10 - EXTERNALLY TOOTHED DISC CARRIER
Fig. 230 Stator Operation
1 - DIRECTION STATOR WILL FREE WHEEL DUE TO OIL
PUSHING ON BACKSIDE OF VANES
2 - FRONT OF ENGINE
3 - INCREASED ANGLE AS OIL STRIKES VANES
4 - DIRECTION STATOR IS LOCKED UP DUE TO OIL PUSHING
AGAINST STATOR VANES
VAAUTOMATIC TRANSMISSION - NAG1 21 - 145
TORQUE CONVERTER (Continued)