Lincoln Corsair: Automatic Transmission - 8-Speed Automatic Transmission – 8F35/8F40 / Description and Operation - Transmission Description - System Operation and Component Description

System Diagram

System Operation

The PCM and its input/output network controls shift timing and line pressure (shift feel).

The transmission control strategy is separate from the engine control strategy in the PCM , although some of the input signals are shared. When determining the best operating strategy for transmission operation, the PCM uses input information from engine and driver related sensors and switches.

In addition, the PCM receives input signals from transmission related sensors and switches and uses these signals to determine transmission operating strategy.

Using all of these input signals, the PCM can determine when the time and conditions are right for a shift or when to apply or release the TCC . It also determines the best line pressure to optimize shift engagement feel. To accomplish this, the PCM uses output solenoids to control transmission operation.

Component Description

Sensors and Switches

The PCM controls the transmission electronic functions through input signals received from the engine and transmission sensors. The PCM uses these inputs to control line pressure, shift time, TCC and shift solenoids.

Typical TR Sensors PWM Output

System Diagram

8F35 Hydraulic Schematic View

Solenoid Body

Solenoids

Solenoid Body

This transmission uses 2 types of solenoids: CIDAS and variable force solenoids.

The solenoid body contains 8 solenoids: 6 shift solenoids SSA , SSB , SSC , SSD , SSE and SSF , 1 TCC solenoid and 1 LPC solenoid. The TCC solenoid is identified by the green electrical connector. The LPC solenoid is identified by the blue electrical connector. The TFT sensor is located in the main control.

The solenoid body has a unique strategy data file that must be downloaded to the PCM . There is a 12-digit solenoid body identification and a 13-digit solenoid body strategy for each solenoid body. When a new solenoid body or transmission is installed, the scan tool must be used to get the solenoid body strategy data file and download it into the PCM .

If the PCM is replaced and the PCM data cannot be inhaled or exhaled, the solenoid body identification and solenoid body strategy must be downloaded into the PCM .

Shift Solenoids

This transmission utilizes six shift solenoids (A-F) that are normally low CIDAS . Unlike previous shift solenoids they are mechanical in nature in that no transmission fluid passes through them. CIDAS s use an armature/pin assembly that moves a control valve in the main control valve body to control and apply hydraulic fluid pressure. Each clutch (A-F) has a corresponding shift solenoid (A-F) that is directly proportional in that zero current equals zero pressure and maximum current equals maximum pressure. Since there is no pressure with zero current if the power is interrupted to the shift solenoids none of the clutch packs are able to engage.

Torque Converter Clutch (TCC) Line Pressure Control (LPC)

The TCC solenoid is a normally low variable force solenoid. The TCC solenoid uses proportional operation. As the current from the TCM decreases, the pressure from the solenoid decreases. As the current from the TCM increases, the pressure from the solenoid increases. The LPC solenoid is a normally high variable force solenoid. When current is high, no fluid pressure passes through the solenoid into the control circuits. When current applied to the solenoid is low, full pressure is passed through to the LPC control circuit and the main regulator valve.

Secondary Fluid Filter

This transmission is equipped with a secondary fluid filter. This 30-micron filter is located at the cooler return passage in the case and filters out any debris that would have otherwise entered the transmission from the cooling system or during service when the lines are disconnected. The fluid passing through this filter goes directly into the lube circuits and then drains back down to the sump. The filter includes a bypass valve that allows fluid to continue to supply the lube circuit in the event the filter becomes blocked or restricted.

Park

  Park Clutch Application Chart

H = Holding

  Park Position Solenoid Operation Chart

Powerflow

Park Position

• With the vehicle in PARK, the hydraulic SOWC holds the overdrive/reaction carrier stationary in anticipation of Reverse or 1st gear engagement.
• All gear element speeds can be predicted and a consistent engagement feel can be achieved.

Reverse

  Reverse Clutch Application Chart

H = Holding

D = Driving

  Reverse Position Solenoid Operation Chart

Powerflow

Reverse Position

• With the selector lever in REVERSE, the hydraulic SOWC holds the overdrive/reaction carrier stationary.
• The B (4, 6, R) clutch drives the reaction sun gear at turbine shaft speed (1000 rpm).
• The reaction ring and output carrier rotates at -337 rpm or a 2.96:1 reserve ratio.

Neutral

  Neutral Clutch Application Chart

H = Holding

  Neutral Position Solenoid Operation Chart

Powerflow

Neutral Position

• With the selector lever in NEUTRAL, the hydraulic SOWC holds the overdrive/reaction planetary carrier stationary.
• The turbine shaft drives the center sun gear.

1st Gear

  1st Gear Clutch Application Chart

H = Holding

  1st Gear Solenoid Operation Chart

Powerflow

1st Gear Position

• In first gear, the A (1, 2, 3, 4, 5) clutch holds the output sun gear stationary.
• The one-way clutch holds the input ring gear stationary.
• The turbine shaft and the input sun gear rotate at 1000 rpm.
• The input carrier and the output ring rotate at 308 rpm.
• The output carrier rotates at 213 rpm or a 4.689:1 ratio.

2nd Gear

  2nd Gear Clutch Application Chart

H = Holding

O/R = Over Running

  2nd Gear Solenoid Operation Chart

Powerflow

2nd Gear Position

• In second gear, the A (1, 2, 3, 4, 5) clutch holds the output sun gear stationary.
• The F (2, 8) clutch holds the overdrive sun gear stationary.
• The turbine shaft and input sun rotate at 1000 rpm.
• The input ring rotates at 186 rpm.
• The input carrier and the output ring rotate at 437 rpm.
• The output carrier rotates at 302 rpm or a 3.306:1 ratio.

3rd Gear

  3rd Gear Clutch Application Chart

H = Holding

O/R = Over Running

  3rd Gear Solenoid Operation Chart

Powerflow

3rd Gear Position

• In third gear, the A (1, 2, 3, 4, 5) clutch holds the output sun gear stationary.
• The C (3, 7) clutch holds the reaction sun gear stationary.
• The turbine shaft and the input sun rotate at 1000 rpm.
• The input ring rotates at 458 rpm.
• The input carrier and the output ring rotate at 480 rpm.
• The output carrier rotates at 332 rpm or a 3.012:1 ratio.

4th Gear

  4th Gear Clutch Application Chart

H = Holding

O/R = Over Running

  4th Gear Solenoid Operation Chart

Powerflow

4th Gear Position

• In fourth gear, the A (1, 2, 3, 4, 5) clutch holds the output sun gear stationary.
• The B (4, 6, R) clutch holds the reaction sun gear at turbine shaft speed (1000 rpm).
• The turbine shaft and input sun rotate at 1000 rpm.
• The input ring rotates at 525 rpm.
• The input carrier and output ring rotate at 751 rpm.
• The output carrier rotates at 520 rpm or a 1.923:1 ratio.

5th Gear

  5th Gear Clutch Application Chart

H = Holding

O/R = Over Running

  5th Gear Solenoid Operation Chart

Powerflow

5th Gear Position

• In fifth gear, the A (1, 2, 3, 4, 5) clutch holds the output sun gear stationary.
• The E clutch holds the input ring gear at turbine shaft speed (1000 rpm).
• The turbine shaft and the input sun rotate at 1000 rpm.
• The input carrier and the output ring rotate at 1000 rpm.
• The output carrier rotates at 692 rpm or a 1.446:1 ratio.

6th Gear

  6th Gear Clutch Application Chart

D = Driving

O/R = Over Running

  6th Gear Solenoid Operation Chart

Powerflow

6th Gear Position

• In sixth gear, the B (4, 6, R) clutch drives the reaction sun gear at turbine shaft speed (1000 rpm).
• The E (5, 6, 7, 8) clutch drives the input ring gear and the reaction sun gear at turbine shaft speed (1000 rpm).
• The turbine shaft and the input sun rotate at 1000 rpm.
• The input carrier and the output ring rotate at 1000 rpm.
• The output carrier rotates at 1000 rpm or a 1:1 ratio.

7th Gear

  7th Gear Clutch Application Chart

H = Holding

D = Driving

O/R = Over Running

  7th Gear Solenoid Operation Chart

Powerflow

7th Gear Position

• In seventh gear, the C (3, 7) clutch holds the reaction sun gear stationary.
• The E (5, 6, 7, 8) clutch drives the reaction planetary carrier at turbine shaft speed (1000 rpm).
• The reaction ring and the output carrier rotates at 1338 rpm or a 0.747:1 ratio

8th Gear

  8th Gear Clutch Application Chart

H = Holding

D = Driving

O/R = Over Running

  8th Gear Solenoid Operation Chart

Powerflow

8th Gear Position

• In eighth gear, the F (2, 8) clutch holds the overdrive sun gear stationary.
• The E (5, 6, 7, 8) clutch drives the reaction planetary carrier at turbine shaft speed (1000 rpm).
• The reaction ring and the output carrier rotates at 1621 rpm or a 0.617:1 ratio.

Transmission External Sealing

The transmission external sealing consists of the following:

• Reusable transmission main control cover gasket.

• Two rubber seals with backing rings to seal transmission cooler tubes to the transmission case.

• Unitized LH halfshaft seal that is pressed into the transmission case.

• Unitized RH halfshaft seal that is pressed into the torque converter housing.

• Selector shaft lip seal that is pressed into the transmission case.

• One rubber seal and two O-rings that seal the Auto-start-stop accumulator to the transmission case.

• One O-ring to seal the TSS/ISSA (Turbine Shaft Speed /Intermediate Shaft Speed) sensor assembly to the transmission case.

• Six pressure test tap plugs in the transmission case.

• Transmission fluid fill plug near the LH halfshaft seal.

• Transmission fluid drain plug at the bottom of the transmission case.

• Torque converter hub lip seal that is pressed into the torque converter housing.

• One plug at the rear of the torque converter housing.

Park by Wire

Park by Wire

• Uses a GSM with a rotary dial or push buttons in place of a mechanical shifter as the customer interface for selecting (P, R, N, D, M).
• The transmission hydraulic controls are modified using a park lock pawl valve connected to the park rod which unlocks and locks the parking pawl from the carrier.
  • Uses clutch C and F hydraulic pressure to push the system out of Park.
  • Once out of Park, line pressure can continue to hold the system out of Park.
• A park lock pawl solenoid is used to allow the system to remain out of Park when the engine is not running.
• The dual TR sensors indicate the state of the Park system and are not used to determine customer selected range, which is now provided by the GSM .