Automatic Transaxle - Overhaul (FN4A-EL): Overview Mazda 3 BL

Component description

POWER FLOW OPERATION COMPONENT DESCRIPTION

Note. All directions of rotation are viewed from the torque converter.

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FORWARD CLUTCH, 3-4 CLUTCH, REVERSE CLUTCH, LOW AND REVERSE BRAKE OPERATION

1. The basic structure is as shown in the figure below. In figure A, the fluid is in the clutch plates (drive plates, driven plates) and the power is not transmitted because of the fluid slippage on each plate. Figure B shows the clutch condition with the hydraulic pressure acted on the piston; the drive plates and the driven plates are pressed tightly together to transmit the clutch drum rotation speed to the hub. When the hydraulic pressure in the piston is drained, the clutches are separated because of the return spring and return to the condition in figure A.

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1. The dished plates used for the reverse clutch and the low and reverse brake reduce the shock caused by the sudden clutch engagement. The piston check ball built in the 2-4 brake drum (reverse clutch) drains the ATF only during freewheel to prevent the hydraulic pressure from increasing to half-engage the clutches because of the residual ATF. In the forward clutch and the 3-4 clutch, the centrifugal balance chamber is installed opposite the general clutch chamber. The centrifugal balance chamber is always filled with the ATF from the exclusive lubrication passage of the turbine shaft.

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2-4 BRAKE BAND OPERATION

1. When the hydraulic pressure acts between the servo retainer and the servo piston (2-4 brake band engagement side), the servo piston acts on the 2-4 brake band to lock the 2-4 brake drum. At the same time, the servo return spring also works as resistance to obtain the optimal 2-4 brake band engagement force. When the hydraulic pressure acts between the servo piston and the transaxle case (2-4 brake band release side), the servo piston is pushed to the servo retainer side. This causes the 2-4 brake band to extend by its own spring force and unlock the 2-4 brake drum. When the hydraulic pressure acts between the servo retainer and the servo piston and between the servo piston and the transaxle case simultaneously, the servo piston is pushed to the servo retainer side and the 2-4 brake drum is unlocked because of the difference in the two areas and spring force.

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ONE-WAY CLUTCH OPERATION

1. The one-way clutch outer race (front internal gear) rotates clockwise (seen from the torque converter side) freely, but the sprags rise to lock the rotation when the outer race tries to rotate counterclockwise.
2. The one-way clutch locks the counterclockwise rotation of the front internal gear, and also locks the counterclockwise revolution of the rear planetary gear via the rear planetary carrier.

Note. All direction of rotation are viewed from the torque converter.

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PARKING MECHANISM OPERATION

1. When the selector lever is moved to P position, the manual shaft and the manual plate move in the direction of the arrow A to the position as shown in the figure below. Then the parking rod component moves in the direction of the arrow B, the parking rod component cam pushes up the parking pawl, and the parking pawl engages the parking gear. If the parking pawl hits the tooth of the parking gear, the parking pawl cannot be pushed up, so only the parking rod component is able to move. The cam presses the spring onto the parking pawl and the actuator. If the vehicle runs even a little under this condition, the wheels rotate and parking gear also rotates slightly. As a result, the parking pawl slides into the groove, and engages the parking gear. Thus, the parking mechanism prevents the vehicle from moving in P position.

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OIL PUMP OPERATION

1. When the inner rotor in the oil pump rotates, the ATF is drawn to the oil pump and then discharged from the oil pump. The discharge amount is proportional to the rotating speed of the torque converter. The ATF discharge amount is controlled by the pressure regulator valve and the pressure control solenoid.

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SHIFT SOLENOID A, B AND C (DUTY-CYCLE TYPE) OPERATION

OPEN: When the electrical current does not flow, the supply port (line pressure) in the solenoid opens and is engaged with the output port (clutch pressure). As a result, hydraulic pressure is supplied to the hydraulic passage for the clutch pressure.

CLOSE: When the electrical current flows, the supply port (line pressure) in the solenoid closes and the output port (clutch pressure) and the drain port are engaged to drain the clutch pressure.

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SHIFT SOLENOID D AND E (ON/OFF TYPE) OPERATION

ON: When the electrical current flows, the output port and the supply port (solenoid reducing pressure) are engaged in the solenoid, and the output pressure becomes equivalent to the solenoid reducing pressure.

OFF: When the electrical current does not flow, the output port and the drain port are engaged in the solenoid, and the output pressure is drained.

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PRESSURE CONTROL SOLENOID (LINEAR TYPE) OPERATION

1. By changing the electrical current value (0 A-1 A) inside the solenoid, the pressure control solenoid adjusts the hold power of the hold pressure valve, controlling the pressure control solenoid pressure to the prescribed hydraulic pressure.

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Clutch operation

1. Set the forward clutch onto the oil pump. CAUTION: Applying compressed air to the assembled clutch pack for longer than 3 s at a time will damage the seal. Do not apply compressed air for more than the aforementioned time when testing the system.
2. Inspect the clutch operation by applying compressed air through the fluid passages shown. Air pressure 392 kPa {4.0 kgf/cm 2 , 57 psi} max.
3. If not as specified, replace parts as necessary.

(See FORWARD CLUTCH DISASSEMBLY/ASSEMBLY ).

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1. Measure the forward clutch clearance. Install the forward clutch in the oil pump, and set the dial gauge. Secure the forward clutch by lightly pressing down with a press, etc. Apply compressed air to the part indicated in the figure and let the forward clutch piston stroke three times. Air pressure 392-441 kPa {4.0-4.5 kgf/cm 2 , 57-63 psi} Apply compressed air and operate the forward clutch piston. Read the value when the indicator of the dial gauge stops. Release the compressed air and read the dial gauge when the forward clutch piston is not operating. Calculate the forward clutch clearance according to the following formula: Step ( 4 ) value - Step ( 5 ) value = Forward clutch clearance. Measure the clearances at four locations (90° apart) by following the steps from ( 3 ) to ( 6 ). Verify that the average value is within the specification below. Forward clutch clearance 1.50-1.80 mm {0.059-0.071 in}
2. If not as specified, replace parts as necessary.

(See FORWARD CLUTCH DISASSEMBLY/ASSEMBLY ).

1. Set the clutch component onto the end cover. CAUTION: Applying compressed air to the assembled clutch pack for longer than 3 s at a time will damage the seal. Do not apply compressed air for more than the aforementioned time when testing the system.
2. Inspect the clutch operation by applying compressed air as shown. Air Pressure 392 kPa {4.0 kgf/cm 2 , 57 psi} max.
3. If not as specified, replace parts as necessary.

(See CLUTCH COMPONENT DISASSEMBLY/ASSEMBLY ).

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1. Measure the reverse clutch clearance. Install the reverse clutch into the end cover, and set the dial gauge. Secure the reverse clutch by lightly pressing down with a press, etc. Apply compressed air to the part indicated in the figure and let the reverse clutch piston stroke three times. Air Pressure 392-441 kPa {4.0-4.5 kgf/cm 2 , 57-63 psi} Apply compressed air and operate the reverse clutch piston. Read the value when the indicator of the dial gauge stops. Release the compressed air and read the dial gauge when the reverse clutch piston is not operating. Calculate the reverse clutch clearance according to the following formula: Step ( 4 ) value - Step ( 5 ) value = Reverse clutch clearance. Measure the clearances at four locations (90° apart) by following the steps from ( 3 ) to ( 6 ). Verify that the average value is within the specification below. Reverse clutch clearance 1.00-1.30 mm {0.039-0.051 in}
2. If not as specified, replace parts as necessary.

(See CLUTCH COMPONENT DISASSEMBLY/ASSEMBLY ).

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1. Measure the 3-4 clutch clearance. Install the 3-4 clutch in the end cover and set the dial gauge. Secure the 3-4 clutch by lightly pressing down with a press, etc. Apply compressed air to the part indicated in the figure and let the 3-4 clutch piston stroke three times. Air pressure 392-441 kPa {4.0-4.5 kgf/cm 2 , 57-63 psi} Apply compressed air and operate the 3-4 clutch piston. Read the value when the indicator of the dial gauge stops. Release the compressed air and read the dial gauge when the 3-4 clutch piston is not operating. Calculate the 3-4 clutch clearance according to the following formula: Step ( 4 ) value - Step ( 5 ) value = 3-4 clutch clearance. Measure the clearances at four locations (90° apart) by following the steps from ( 3 ) to ( 6 ). Verify that the average value is within the specification below. 3-4 clutch clearance Drive plate part number: FN11 19 370 1.00-1.30 mm {0.039-0.051 in} Drive plate part number: FNE1 19 370 1.10-1.40 mm {0.043-0.055 in}
2. If not as specified, replace parts as necessary.

(See CLUTCH COMPONENT DISASSEMBLY/ASSEMBLY ).

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1. Measure the bushing of the 3-4 clutch hub. Bushing inner diameter Standard: 18.000-18.018 mm {0.70866-0.70936 in} Maximum: 18.038 mm {0.71016 in}
2. If not as specified, replace the 3-4 clutch hub. (See «CLUTCH COMPONENT DISASSEMBLY/ASSEMBLY»(ref-345201-S05150076772009102000000) ).
3. Measure the bushing of the 2-4 brake drum. Bushing inner diameter Standard: 55.005-55.030 mm {2.16555-2.16653 in} Maximum: 55.050 mm {2.16732 in}
4. If not as specified, replace the 2-4 brake drum. (See «CLUTCH COMPONENT DISASSEMBLY/ASSEMBLY»(ref-345201-S05150076772009102000000) ).

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1. Set the front internal gear and one-way clutch component to the one-way clutch inner race. Verify that the one-way clutch rotates smoothly when turned counterclockwise and locks when turned clockwise.
2. If not as specified, replace parts as necessary. (See «FRONT INTERNAL GEAR ONE-WAY CLUTCH COMPONENT DISASSEMBLY/ASSEMBLY»(ref-345201-S12997740402009102000000) ).

1. Inspect the clutch operation by applying compressed air as shown. Air pressure 392 kPa {4.0 kgf/cm 2 , 57 psi} max.
2. If not as specified, replace parts as necessary. (See «LOW AND REVERSE BRAKE AND ONE-WAY CLUTCH INNER RACE DISASSEMBLY/ASSEMBLY»(ref-345201-S26841177032009102000000) ).

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1. Measure the low and reverse brake clearance. Set the dial gauge to the low and reverse brake. Set the measuring point of the dial gauge to the low and reverse brake piston. Apply compressed air to the part indicated in the figure and let the low and reverse brake piston stroke three times. Air pressure 98.1 kPa {1.0 kgf/cm 2 ,14 psi} Apply compressed air and operate the low and reverse brake piston. Read the value when the indicator of the dial gauge stops. Release the compressed air and read the dial gauge when the low and reverse brake piston is not operating. Calculate the low and reverse brake clearance according to the following formula: Step ( 4 ) value - Step ( 5 ) value = low and reverse brake clearance. Measure the clearances at four locations (90° apart) by following the steps from ( 3 ) to ( 6 ). Verify that the average value is within the specification below: Low and reverse brake clearance 2.20-2.50 mm {0.087-0.098 in}
2. If not as specified, replace parts as necessary. (See «LOW AND REVERSE BRAKE AND ONE-WAY CLUTCH INNER RACE DISASSEMBLY/ASSEMBLY»(ref-345201-S26841177032009102000000) ).

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