Description and operating principle of automatic transmission

Description of the gearbox in the block with the driving axle

The automatic transmission used in this car is a new development.

It is a fully automatic, electronically controlled, four-speed transmission designed for use in front-wheel drive vehicles.

The short designation of the gearbox is 4F27E, which stands for:

• 4 - 4-speed gearbox,
• F - front wheel drive,
• 27 - Maximum input torque after torque converter: 365 Nm (270 lb-ft)
• E - fully electronic control.

Individual gear ratio values are achieved using a two-stage planetary gear, the stages of which are arranged one after the other.

The individual elements of the planetary gear stages are driven or held by means of three multi-disc clutches, multi-disc brakes, band brakes and a single-acting roller clutch.

Torque is transmitted to the final drive via an intermediate gear.

The working fluid is replaced in accordance with the Scheduled Maintenance Guide supplied with the vehicle. Electrical and hydraulic functions are controlled by the EEC V powertrain control module with a 104-pin connector. The manual gear selector lever gives the driver a choice between "P", "R", "N", "1", "2" and "D" gears.


In the "D" driving range, the O/D switch located on the gear selector lever can also be used to prevent the transmission from shifting to 4th gear or to shift the transmission from 4th to 3rd gear.

To reduce fuel consumption, the torque converter locking clutch in 3rd and 4th gears is locked by the PCM depending on the position of the throttle valve and the vehicle speed.

The transmission features Electronic Shift Control (ESSC), which ensures smooth gear shifting throughout the life of the transmission.

The hydraulic emergency operating program maintains limited transmission operation in the event of failure of important electrical components.

The transmission can be tested using the FDS 2000 or WDS via the data link connector (DLC) located in the passenger compartment.

• 1st gear: 2.816:1
• 2nd gear: 1.498:1
• 3rd gear: 1.000:1
• 4th gear: 0.726:1
• Reverse Gear Ratio: 2.649:1

Torque converter housing with torque converter and working fluid pump

Pos.	Spare Part No	Name
1	-	Torque converter assembly
2	-	Differential seal assembly
3	-	Secondary Shaft Speed Sensor (OSS)
4	-	Torque converter housing
5	-	Working fluid pump seal assembly
6	-	Working fluid pump seal
7	-	Working fluid pump assembly
8	-	Forward Clutch Cylinder Seal
9	-	Thrust washer of the working fluid pump support

Forward clutch

Pos.	Spare Part No	Name
1	-	Turbine shaft assembly
2	-	Forward Clutch Piston Assembly
3	-	Forward Clutch Piston Return Spring Assembly
4	-	Forward Clutch Balancing Piston
5	-	Forward Clutch Balancing Piston Retaining Ring
6	-	Forward clutch steel separator disc (4 pcs.)
7	-	Forward Clutch Friction Disc Assembly (Forward, 4 pcs.)
8	-	Forward/Direct Drive Clutch Pressure Plate (1 pc. for each clutch)
9	-	Retaining ring (selective selection)
10	-	Forward Clutch Cylinder Hub

Differential assembly and final drive input - vehicles manufactured up to 06.2000.

Pos.	Spare Part No	Name
1	-	Differential Bearing Adjusting Shim (Shim)
2	-	Differential bearing outer ring
3	-	Inner ring of bearing with rollers
4	-	Bearing assembly
5	-	OSS Sensor Wheel
6	-	Differential and pinion assembly of the gearbox in block with the driving axle
7	-	Thrust washer of differential satellite (2 pcs.)
8	-	Differential satellite (2 pcs.)
9	-	Differential axle gear (2 pcs.)
10	-	Thrust washer of half-axle gear (2 pcs.)
11	-	Pin
12	-	Differential satellite axle
13	-	Adjusting shim (shim) of the roller bearing of the transmission shaft
14	-	Outer ring of the roller bearing of the transmission shaft
15	-	Inner ring of bearing with rollers
16	-	Bearing assembly of the transmission shaft (2 pcs.)
17	-	Secondary gear of the transmission shaft
18	-	Parking gear pinion
19	-	Primary gear of the transmission shaft
20	-	Transfer shaft funnel
21	-	Primary gear of the main transmission
22	-	Inner ring of bearing with rollers
23	-	Outer bearing ring
24	-	Bearing assembly (2 pcs.)
25	-	Remote element
26	-	Retaining ring
27		Screw

Differential assembly and final drive input - vehicles manufactured from 06.2000 onwards.

Pos.	Spare Part No	Name
1	-	Differential Bearing Adjusting Shim (Shim)
2	-	Differential bearing outer ring
3	-	Inner ring of bearing with rollers
4	-	Bearing assembly
5	-	OSS Sensor Wheel
6	-	Differential and pinion assembly of the gearbox in block with the driving axle
7	-	Thrust washer of differential satellite (2 pcs.)
8	-	Differential satellite (2 pcs.)
9	-	Differential axle gear (2 pcs.)
10	-	Thrust washer of half-axle gear (2 pcs.)
11	-	Pin
12	-	Differential satellite axle
13	-	Adjusting shim (shim) of the roller bearing of the transmission shaft
14	-	Outer ring of the roller bearing of the transmission shaft
15	-	Inner ring of bearing with rollers
16	-	Bearing assembly of the transmission shaft (2 pcs.)
17	-	Transfer shaft gear assembly
18	-	Transfer shaft funnel
19	-	Primary gear of the main transmission
20	-	Inner ring of bearing with rollers
21	-	Outer bearing ring
22	-	Bearing assembly (2 pcs.)
23	-	Remote element
24	-	Retaining ring
25	-	Screw

Clutches and planetary gear

Pos.	Spare Part No	Name
1	-	Low/Reverse Clutch Piston
2	-	Low/Reverse Clutch Return Spring
3	-	OWC Low Gear Inner Ring
4	-	OWC Low Gear Retaining Ring
5	-	Low/Reverse Clutch Diaphragm Spring
6	-	Low/Reverse Clutch Steel Spacer Ring (5 pcs.)
7	-	Low/Reverse Clutch Friction Disc Assy (5 pcs.)
8	-	Low/Reverse Clutch Pressure Plate
9	-	Low/Intermediate Clutch Disc Retaining Ring (Selective Selection)
10	-	Low range single acting clutch lock
11	-	OWC low gear single acting clutch assembly
12	-	Retaining ring
13	-	Front crown gear
14	-	Front planetary gear assembly
15	-	Thrust bearing assembly of front planetary gear carrier
16	-	Retaining ring
17	-	Front Planetary Sun Gear Assembly
18	-	Front Planetary Sun Gear Thrust Bearing Assembly
19	-	Rear planetary gear assembly
20	-	Retaining ring

Clutches and band brake

Pos.	Spare Part No	Name
1	-	Reverse clutch retaining ring
2	-	Rear Planetary Sun Gear Assembly
3	-	Rear Planetary Sun Gear Thrust Bearing Assembly
4	-	Direct Drive Clutch Hub Assembly
5	-	Retaining ring
6	-	Forward/Direct Drive Clutch Pressure Plate (1 each)
7	-	Friction disc assembly for forward/direct drive clutches (for forward clutch - 4 pcs., for direct drive clutch - 3 pcs.)
8	-	Direct Drive Clutch Steel Disc (3 pcs.)
9	-	Direct Drive Clutch Balancing Piston Retaining Ring
10	-	Balancing piston of direct drive clutch
11	-	Return Spring Assembly Piston Forward/Direct Clutch
12	-	Direct Drive Clutch Piston Assembly
13	-	Thrust bearing assembly direct drive clutch
14	-	Direct Drive Clutch Cylinder Assembly
15	-	Reverse clutch retaining ring (selective selection)
16	-	Reverse clutch pressure plate
17	-	Steel disc of reverse gear clutch (2 pcs.)
18	-	Friction disc assembly for reverse clutch (2 pcs.)
19	-	Reverse clutch retaining ring
20	-	Reverse clutch stopper
21	-	Reverse clutch piston return spring
22	-	Reverse clutch piston assembly
23	-	Intermediate/overdrive drum assembly
24	-	Band brake assembly intermediate/overdrive

Main control unit assembly

Pos.	Spare Part No	Name
1	-	Manual control valve assembly
2	-	Spring retainer plate (7 pcs.)
3	-	Control spring for bypass clutch control valve (4 pcs.)
4	-	Bypass valve for clutch control (2 pcs.)
5	-	Modulating valve spring)
6	-	Line pressure modulation valve (and torque converter release) (2 pcs.)
7	-	Bolt M6x40 (3 pcs.)
8	-	Bolt M6x30 (5 pcs.)
9	-	Valve block seal
10	-	Bolt M6x60 (5 pcs.)
11	-	Upper control valve block
12	-	Valve Body Gasket/Disc Assembly
13	-	Valve Block Separator Gasket
14	-	Lower control valve block
15	-	Main control valve stopper
16	-	Main control valve retaining plate
17	-	Main line pressure regulating valve spring
18	-	Main line pressure regulating valve
19	-	Solenoid control valve spring
20	-	Solenoid control valve
21	-	Intermediate gear servo unit accumulator spring
22	-	Intermediate gear servo unit storage piston
23	-	Torque converter control valve spring
24	-	3-4 lock and switch control valve (2 pcs.)
25	-	Solenoid valve block gasket
26	-	Shift control solenoid valve (2 pcs.)
27	-	Pressure control solenoid valve assembly
28	-	Screw M6x15 (7 pcs.)
29	-	Screw M6x72 (2 pcs.)
30	-	Electromagnetic throttle valve block
31	-	Solenoid valve assembly for switching control (3 pcs.)
32	-	Bracket for electromagnetic valves for switching control H/DWN

Crankcase assembly

Pos.	Spare Part No	Name
1	–	Parking latch axle
2	–	Parking brake pawl
3	–	Pawl return spring
4	–	Pin
5	–	Carter
6	–	Crankcase jet plug
7	–	Service identification plate
8	–	TSS sensor
9	–	Bolt M6-1 x 20
10	–	O-ring
11	–	Crankcase stud
12	–	Rubber vent cover
13	–	Breather tube
14	–	Accelerator band brake anchor stud
15	–	Differential seal
16	–	Hexagon socket head 1/8-27
17	–	Connector? x 5/8 x 22.9
18	–	Crankcase dowel pin
19	–	Servo piston return spring
20	–	Servo block piston assembly with intermediate and accelerating gear seal
21	–	Screw M6-1 x 20
22	–	Cover of the servo block of the intermediate and accelerating transmission band brake
23	–	Intermediate and overdrive servo unit cover seal
24	–	Neutral/Drive Accumulator Piston
25	–	Neutral/Drive Shift Accumulator Outer Spring
26	–	Neutral/Drive Shift Inner Accumulator Spring
27	–	Shift Accumulator Piston 1-2
28	–	1-2 shift accumulator outer spring
29	–	1-2 shift accumulator internal spring
30	–	Line pressure test plug
31	–	Transfer oil line
32	–	Parking Latch Adjustment Actuator
33	–	Parking Latch Actuator Plate

Seals, O-rings and gaskets

Pos.	Spare Part No	Name
1	-	Reverse clutch piston assembly
2	-	Direct Drive Clutch Piston Assembly
3	-	Balancing piston of direct drive clutch
4	-	Low/Reverse Clutch Piston
5	-	O-ring for turbine speed sensor
6	-	Balancing piston of direct drive clutch
7	-	Direct Drive Clutch Piston Assembly
8	-	Forward and direct drive clutch cylinder seals (4 pcs.)
9	-	Seal in the working fluid pump assembly
10	-	Working fluid pump seal
11	-	Differential seal assembly
12	-	Secondary Shaft Speed Sensor O-Ring
13	-	Valve block seal (2 pcs.)
14	-	Hand shaft seal (2 pcs.)
15	-	Working fluid filter seal
16	-	Overdrive Servo Cover Seal
17	-	Piston and seal assembly of intermediate and overdrive servo unit
18	-	Solenoid valve block gasket
19	-	Control valve block gasket (2 pcs.)
20	-	Crankcase cover seal (2 pcs.)
21	-	Reverse clutch cylinder seal (2 pcs.)

Retaining rings

Pos.	Spare Part No	Name
1	-	Reverse clutch retaining ring
2	-	Low/Reverse Clutch Disc Retaining Ring (SEL)
3	-	Main gear retaining ring
4	-	Forward Clutch Balancing Piston Ring
5	-	Forward/Direct Drive Clutch Disc Retaining Ring (Selec. Select)
6	-	Front Planetary Sun Gear Retaining Ring
7	-	OWC Low Gear Retaining Ring
8	-	Reverse clutch retaining ring (selective selection)
9	-	DC balancing piston retaining ring
10	-	Forward/Direct Drive Clutch Planetary Gear Retaining Ring
11	-	Reverse clutch spring retaining ring
12	-	Forward/Direct Drive Clutch Disc Retaining Ring (Selec. Select)
13	-	Rear Planetary Gear Retaining Ring Assembly

Rolling and plain bearings (bushings) and thrust washers

Pos.	Spare Part No	Name
1	-	Thrust bearing No.3 in the rear planetary gear sun gear assembly
2	-	Thrust Bearing Assy No.5 Front Planetary Sun Gear
3	-	Thrust bearing assembly No.6 front planetary gear carrier
4	-	Inner ring of primary shaft bearing complete with rollers (2 pcs.)
5	-	Primary shaft bearing outer ring (2 pcs.)
6	-	Thrust washer of the working fluid pump support
7	-	Inner ring of differential bearing with rollers (2 pcs.)
8	-	Differential bearing outer ring (2 pcs.)
9	-	Side washer of front axle differential (2 pcs.)
10	-	Front axle differential bearing thrust washer (2 pcs.)
11	-	Outer ring of roller bearing of transmission shaft (2 pcs.)
12	-	Inner ring of the transmission shaft bearing with rollers (2 pcs.)
13	-	Thrust bearing No.4 in the rear planetary gear carrier assembly
14	-	Thrust Bearing No.2 Assy Sun Gear Rear Planetary Gear
15	-	Thrust bearing No.1 in direct drive clutch cylinder assembly

Range selection

The gearbox range selection mechanism in the block with the driving axle has six positions: "P", "R", "N", "D", "2" and "1".

Position "P" of the manual gear selector lever

When the manual gear selector lever is in the "P" position, no gear is selected. The parking pawl is engaged manually using the manual gear selector lever cable and the shift shaft.

For safety reasons, the parking brake must be applied whenever the vehicle is parked.

Position "R" of the manual gear selector lever

When the manual gear selector lever is in the "R" position, reverse gear is selected. Reverse gear allows the vehicle to move in the opposite direction with a low gear ratio.

Position "N" of the manual gear selector lever

When the manual gear selector lever is in the "N" position, no gear is selected. The transmission is not locked, so the wheels can rotate.

The car should be started in neutral gear.

Position "D" of the manual gear selector lever

With the manual gear selector in the "D" position and the O/D switch not pressed, the transmission control allows selection of all gears. When the O/D switch is pressed, shifting to 4th gear is blocked or the transmission downshifts to 3rd gear.

Position "1" of the manual gear selector lever

When the manual gear selector lever is in position "1", only first gear is selected. In addition to the one-way clutch of 1st gear, the gearbox control locks the reverse brake to activate the engine braking effect when coasting.

If the manual gear selector lever is moved to position "1" when the vehicle speed is too high for 1st gear, the gearbox control will allow downshifting only after the corresponding vehicle speed has been reached.

Position "2" of the manual gear selector lever

When the manual gear selector lever is in position "2", only the second gear is selected. The gearbox control does not allow switching to the first gear.

If the manual gear selector lever is moved to position "2" when the vehicle speed is too high for 2nd gear, the transmission control will not allow downshifting until the corresponding vehicle speed has been reached.

General overview of design and functions

Pos.	Spare Part No	Name
1	-	Intermediate/overdrive band brake
2	-	Front planetary gear ring gear
3	-	Low gear/Reverse gear coupling
4	-	Forward clutch
5	-	Working fluid pump and torque converter stator support
6	-	Torque converter
7	-	Primary shaft of the gearbox
8	-	Differential
9	-	Transfer shaft assembly
10	-	Main gear pinion
11	-	Low gear single acting clutch
12	-	Reverse gear clutch
13	-	Direct drive clutch

Torque converter and torque converter lock-up clutch

Pos.	Spare Part No	Name
1	-	Torque converter housing and impeller
2	-	Turbine
3	-	Stator
4	-	Torque converter locking clutch
5	-	Primary shaft of the gearbox

The torque converter hydraulically transmits torque from the engine to the input shaft of the transmission.

The stator amplifies the torque delivered to the input shaft (approximately 85% of the speed difference between the impeller and the turbine).

The stator is made of synthetic resin to reduce weight.

To increase the efficiency of the automatic transmission, the torque converter has a clutch. When the locking clutch of the torque converter is locked, torque is transmitted directly from the crankshaft through the housing of the torque converter to the input shaft of the transmission.

In 3rd and 4th gear, the torque converter clutch is hydraulically engaged by the PCM via the solenoid valves in the valve block. Clutch engagement depends on the throttle position, vehicle speed, and manual gear selector lever position.

Oil pump and stator support

Pos.	Spare Part No	Name
1	-	Stator support
2	-	Working fluid pump
3	-	Impeller of the torque converter
4	-	Stator

The working fluid pump is a sickle-shaped gear pump that is directly driven from the crankshaft by means of drive elements located on the impeller hub of the torque converter. The working fluid pump is bolted to the torque converter housing.

The stator support is part of the working fluid pump. The splines on the support locate and hold the torque converter stator.

Planetary gear

The specific gears of the gearbox are shifted by means of the operation of two planetary gear stages located one behind the other.

Clutches and band brakes

Individual gear ratios are selected via four multi-plate clutches, a band brake and a single-acting roller clutch.

The elements are controlled by the PCM using pulse width modulated (PWM) solenoid valves

Valve block

Pos.	Spare Part No	Name
1	-	PWM solenoid valves
2	-	Electromagnetic switching valves (on/off)
3	-	Main Control Valve (Variable Force Solenoid - VFC)

The valve block contains six electromagnetic valves:

• three PWM solenoid valves (pulse width modulated solenoid valves),
• two electromagnetic switching valves (on/off),
• one main control valve (variable force solenoid valve).

Individual clutches and band brakes receive pressure from PWM solenoids and shift solenoids (on/off), and thus gear shifting occurs.

PWM solenoid valves allow direct actuation of clutches and brakes to ensure very smooth gear shifting by performing precise pressure adjustment.

On/off shift solenoids switch hydraulic flow to the clutches and band brakes, thus reducing the number of modulating valves required. The main control valve (variable force solenoid valve) ensures that sufficient hydraulic pressure is available under all operating conditions.

PWM Solenoid Valves No.1-3

Solenoid valves PWM 1, 2 and 3 control the pressure supplied to the band brakes and clutches.

On/Off Switching Solenoid Valves No.1 and 2

The shift solenoid valves (on/off) switch various oil passages in the valve block to supply pressure to individual clutches and band brakes.

The use of electromagnetic gearshift valves is necessary for direct actuation of individual clutches and band brakes.

Main control valve

The main control valve (variable force solenoid valve) controls the main line pressure required for the individual transmission ranges.

The pressure in the main line is regulated depending on the current engine load.

Internal switching mechanism

Pos.	Spare Part No	Name
1	-	Lever on the hand shaft
2	-	Manual shaft
3	-	Parking Latch Activation Lever
4	-	Manually operated valve actuator lever
5	-	Manually operated valve (in valve block not shown)

The shift lever is fixed to a section of the hand shaft that has a square cross-section. The axial movement of the selector lever cable is converted into rotation of the hand shaft.

In the gearbox, the hand shaft operates the parking pawl release lever and the manual valve actuator lever. A manually operated valve is a valve that is operated entirely manually; it is moved by means of a manually operated valve actuator lever located in the valve block.

The manually operated valve ensures operation when the hydraulic emergency program is active.

External gear shift mechanism

Pos.	Spare Part No	Name
1	-	Selector lever assembly
2	-	Selection lever
3	-	Selector lever cable
4	-	Guide
5	-	Clamp
6	-	Lever on the shift shaft

The manual selector lever cable on the gearbox side is connected to a ball on the lever located on the hand shaft.

The cable supports are secured to the gearbox housing and then attached to the manual selector lever bracket.

The manual selector lever cable adjuster is located on the cable housing on the gearbox side.

On the side of the manual selection lever, the cable is clamped in the ball.

Intermediate gear and final drive assembly

Pos.	Spare Part No	Name
1	-	Main gear pinion
2	-	Drive gear of the transmission shaft
3	-	Driven gear of the transmission shaft
4	-	Differential

The main gear drive pinion has a splined connection with the planetary gear front stage carrier and drives the intermediate gear drive pinion.

The driven gear of the transmission shaft drives the main gear assembly. The torque is transmitted to the axle shafts via the main gear. The differential compensates for the difference in the rotation speed of the axle shafts.

The intermediate gear is designed so that the final drive ratio can be adapted to the specific needs of using the automatic transmission with different engines.

Gearbox Control Overview

Pos.	Spare Part No	Name
1	-	PCM EEC V
2	-	Data Link Connector (DLC)
3	-	Throttle Position Sensor (TP)
4	-	Mass Air Flow (MAF) and Intake Air Temperature (IAT) Sensors
5	-	Crankshaft Position Sensor (CKP)
6	-	Secondary Shaft Speed Sensor (OSS)
7	-	Turbine Shaft Speed Sensor (TSS)
8	-	Transmission Range (TR) Sensor
9	-	Transmission Fluid Temperature (TFT) Sensor
10	-	Overdrive (O/D) switch
11	-	Brake light switch
12	-	Shift Lock Solenoid Valve for Selector Lever
13	-	Ignition Key Lock Electromagnet
14	-	Air conditioning relay
15	-	Solenoid valves in the valve block
16	-	Powertrain indicator light on the instrument panel
17	-	O/D indicator light on instrument cluster

Powertrain Control Module (PCM)

Pos.	Spare Part No	Name
1	-	RCM EEC V
2	-	Inertial Fuel Shutoff (IFS)

The PCM is located under the trim panel on the right A-pillar. On vehicles with an automatic transmission, the PCM EEC V controls the transmission as well as the engine management system. In this case, a module with a 104-pin connector is used.

The PCM evaluates input signals from individual sensors and operates the solenoids in the transmission valve block precisely according to the operating condition.

Transmission diagnostic tests can be performed via the data link connector (DLC) located above the central junction box (CJB).

Emergency work program

If, due to incorrect signals, correct gear shifting cannot be guaranteed, the PCM starts operating in the emergency operating program mode.

The driver will be aware of the emergency operating program by the powertrain indicator lamp lighting up on the instrument panel. Continuous monitoring is guaranteed in the following limited conditions:

• maximum pressure in the main line;
• 3rd gear with the manual gear selector lever in positions "D", "2" and "1" without engaging the torque converter locking clutch;
• reverse gear when the manual gear selector lever is in the "R" position.