Mechanical Components and Functions

Mechanical Components and Functions

Planetary Gearset

This transmission has 2 planetary gearsets (front and rear) to provide operation in reverse and 6 forward speeds.

The front planetary gearset is a single planetary gearset and has the following components:

- Front planetary No. 1 sun gear

- Front planetary carrier

- Front planetary ring gear (part of the input shaft assembly)

The input shaft rotates the front ring gear as a driving member. The front sun gear is connected to the fluid pump and is held stationary. The front ring gear rotates the front planetary carrier assembly with a reduction ratio of 1.52:1.

The front planetary carrier assembly is the only output member of the front planetary gearset in reverse, 1st, 2nd and 3rd gear. The front planetary gearset provides a 1.52:1 gear ratio to the rear planetary gearset.

In 4th and 5th gear, both the front ring gear and front planetary carrier assembly are output members of the front planetary gearset. The front planetary gearset provides both a 1:1 and 1.52:1 gear ratio to different members of the rear planetary gearset.

In 6th gear, the front ring gear is the only output member of the front planetary gearset. The front planetary gearset provides a 1:1 gear ratio to the rear planetary gearset.

The rear planetary gearset is a ravigneaux planetary gearset and has the following components:

- Rear planetary No. 2 sun gear

- Rear planetary No. 3 sun gear

- Rear planetary carrier assembly (2 sets of pinion gears)

- Rear planetary ring gear assembly

Power flow through the rear planetary gearset is as follows:

- In reverse, rear sun gear No. 2 is driven, the rear planetary carrier is held and the ring gear is the output (2.24:1 with reverse direction)

- In 1st gear, sun gear No. 3 is driven, the rear planetary carrier is held and the ring gear is the output (2.74:1)

- In 2nd gear, sun gear No. 3 is driven, sun gear No. 2 is held and the ring gear is the output (1.54:1)

- In 3rd gear, sun gear No. 3 and sun gear No. 2 are driven and the ring gear is the output (1:1)

- In 4th gear, sun gear No. 3 and the rear planetary carrier are driven and the ring gear is the output (1.14:1)

- In 5th gear, sun gear No. 2 and the rear planetary carrier are driven and the ring gear is the output (0.87:1)

- In 6th gear, the rear planetary carrier is driven, sun gear No. 2 is held and the ring gear is the output (0.69:1)

Planetary Gearset Exploded View










Forward Clutch (A)

The forward clutch (A) connects the front planetary carrier to the rear No. 3 sun gear. This provides a gear reduction ratio of 1.52:1 from the input shaft to rear sun gear No. 3. The forward clutch (A) is applied in 1st, 2nd, 3rd and 4th gears.

Regulated hydraulic pressure from the regulator valve in the valve body pushes the forward clutch (A) piston against the forward clutch (A) pack to apply the clutch. The front planetary carrier and the rear No. 3 sun gear are connected as a result of the clutch being applied.

Forward Clutch (A) Exploded View










Direct Clutch (B)

The direct clutch (B) connects the front planetary carrier to the rear No. 2 sun gear. This provides a gear reduction ratio of 1.52:1 from the input shaft to rear sun gear No. 2. The direct clutch (B) is applied in reverse, 3rd and 5th gears.

Regulated hydraulic pressure from the regulator valve in the valve body pushes the direct clutch (B) piston against the direct clutch (B) pack to apply the clutch. The front planetary carrier and the rear No. 2 sun gear are connected as a result of the clutch being applied.

Direct Clutch (B) Exploded View










Intermediate Clutch (C)

The intermediate clutch (C) holds the rear planetary No. 2 sun gear stationary to the transmission case. The intermediate clutch (C) is applied in 2nd and 6th gears.

Regulated hydraulic pressure from the regulator valve in the valve body pushes the intermediate clutch (C) piston against the intermediate clutch (C) pack to apply the clutch.

Intermediate Clutch (C) Exploded View










Low/Reverse Clutch (D) and Low/One-Way Clutch (OWC)

The low/reverse clutch (D) holds the rear planetary carrier stationary to the transmission case. The low/reverse clutch (D) is applied in park, reverse, neutral and 1st gear below 5 kph (3 mph).

Regulated hydraulic pressure from the regulator valve in the valve body pushes the low/reverse clutch (D) piston against the low/reverse clutch (D) pack to apply the clutch.

The low/One-Way Clutch (OWC) is a brake clutch that holds the rear planetary carrier in one direction and allows it to freewheel in the opposite direction eliminating engine braking in 1st gear when the transmission is in drive, above 5 kph (3 mph) only.

Low/Reverse Clutch (D) and Low/One-Way Clutch (OWC) Exploded View










Overdrive Clutch (E)

The overdrive clutch (E) connects the input shaft with the rear planetary carrier. The overdrive clutch (E) is applied in 4th, 5th and 6th gears.

Regulated hydraulic pressure from the regulator valve in the valve body pushes the overdrive clutch (E) piston against the overdrive clutch (E) pack to apply the clutch.

Overdrive Clutch (E) Exploded View










External Sealing

The pump assembly has a lip-type seal for the torque converter impeller hub. The pump assembly uses a large O-ring to seal the transmission case. The pump bolts also seal the pump to the transmission case.

The manual control lever shaft has a lip seal for its bore in the transmission case.

The transmission fluid pan uses a reusable gasket.

The output shaft flange has a lip-type seal that seals the flange to the transmission case.

The transmission case plug provides access to the park pawl shaft. The plug has a seal that is serviced as an assembly with the plug.

The main control leadframe connector sleeve has a seal for the transmission case bore. The seal is serviced as an assembly with the bulkhead connector sleeve.

The plug for the fluid level indicator uses an O-ring seal.

External Sealing (Gaskets, O-rings and Seals)














Bushings, Bearings and Thrust Washer Locations

This transmission supports the rotating components of the transmission with bushings, bearings and thrust washers.

The pump assembly support thrust washer controls the amount of end play for components between the pump assembly and the center support (forward/overdrive clutch assembly, direct clutch cylinder).

The T8 thrust bearing outer race controls the amount of end play for components between the center support and the rear of the transmission case (rear planetary gearset assembly, output shaft assembly).










Lubrication

This transmission provides lubrication for rotating mechanical components through one main hydraulic circuit. The general flow of lubrication moves from the front of the transmission, through the input and intermediate shafts, to the rear of the transmission.

Transmission fluid from the pump assembly and the torque converter exit the transmission case to go to the transmission fluid cooler through the bottom of the transmission fluid cooler tube and returns to the transmission through the top of the transmission fluid cooler tube.

With lower transmission fluid temperatures, the thermal bypass valve in the transmission case bypasses the transmission fluid cooler tubes and redirects the fluid to the lubrication circuit. As transmission fluid temperature increases, the thermal bypass valve directs the fluid to the transmission fluid cooler.

Transmission fluid from the transmission fluid cooler or the thermal bypass valve enters the main lubrication circuit from the top of the transmission fluid cooler tube port.

Transmission fluid in the lubrication circuit flows to each of the balance pistons for the forward (A), direct (B) and overdrive (E) clutches. The balance pistons prevent unwanted clutch application when the clutch cylinder rotates at high speeds and hydraulic controls have released the clutch.

Lubrication Passages










Park

The park gear is part of the output shaft assembly. The park gear has lugs on its overdrive surface that the park pawl engages to lock the output shaft.

The park lock prevents the vehicle wheels from rotating by allowing the transmission case to hold the output shaft stationary through the park pawl. When the park pawl is engaged in the park gear, the output shaft is held stationary.

When the manual control lever is rotated to the PARK position, the park lock works as follows:

- The detent assembly (connected to the manual control shaft) rotates and pushes the park pawl actuator rod into the park pawl. The actuator rod is spring loaded.

- The actuator rod is guided into the park pawl by the park pawl abutment.

- When the park pawl actuator rod is pushed into the park pawl, the park pawl pivots into the park gear and engages with the lugs.

- The park pawl holds the output shaft to the transmission case.