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Service Transmission


Checking Transmission (Z225)

The Z225 transmission is a sealed component. No maintenance is required on this transmission. If you suspect any transmission problems, please contact your authorized dealer.

Transmission Oil (Z425 and Z445)

NOTE: Machine is filled with John Deere Low Viscosity HY-GARD® (J20D) transmission oil at the factory. Do not mix oils.

Use only Low Viscosity HY-GARD® (J20D) transmission oil. DO NOT use type “F” automatic transmission fluid.

IMPORTANT: Avoid damage! Use John Deere Low Viscosity HY-GARD® (J20D) transmission oil to reduce transmission noise and to increase response time for the hydraulics and power steering.

• Do not drain or change hydrostatic transmission fluid.

• See your John Deere dealer for service.


John Deere Low Viscosity HY-GARD® (J20D) transmission oil is specially formulated to provide maximum protection against mechanical wear, corrosion, and foaming. It may be used in all operating temperatures.

Checking Transaxle Oil Level (Z425 and Z445)

NOTE: On Z225 models, the transaxle is a sealed component. No maintenance is required on this transaxle. If you suspect any transmission problems, please contact your authorized dealer.

1. Park machine safely on a level surface. (See Parking Safely in the SAFETY section.)

IMPORTANT: Avoid damage! Hot hydraulic oil will expand and show incorrect oil level. Check oil level:

• When oil is cold.

• With engine not running.


2. Allow machine to cool.

3. Raise operator’s seat.


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4. Locate transaxle oil reservoir (A) at rear of machine. Reservoir is marked FULL (B).

IMPORTANT: Avoid damage! Contamination can damage the hydraulic system. Clean thoroughly around reservoir fill cap before opening.


5. If oil level is low, clean area around reservoir cap (C).

6. Remove cap.

7. Add John Deere Low Viscosity HY-GARD™ (J20D) until oil level is at FULL mark on reservoir.

8. Install cap.

9. Start engine.

10. Operate machine forward and in reverse several times.

11. Park machine safely on a level surface. (See Parking Safely in the SAFETY section.)

12. Wait at least 3 minutes for hydraulic oil to cool.

13. Check oil level again. Add oil if necessary.

Changing Transaxle Oil and Filter (Z425 and Z445)

NOTE: Z225 model: The transaxle is a sealed component. No maintenance is required on this transaxle. If you suspect any transmission problems, please contact your authorized dealer.

Z425 and Z445 models: Changing transaxle oil and filter is not required as a regular service interval and should not be changed unless servicing other components.

1. Park machine safely on a level surface. (See Parking Safely in the SAFETY section.)

IMPORTANT: Avoid damage! Contamination can damage the hydraulic system. Clean thoroughly around reservoir fill cap before opening.



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2. Raise operator’s seat, and clean area around reservoir cap (A). Remove cap.


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Picture Note: View from rear of machine.

3. Clean area around hydraulic oil filter (B).

4. Place drain pan with at least a 9.9 L (10.5 qt) capacity under hydraulic oil filter, turn filter counterclockwise to remove and allow oil to drain completely.

5. Apply a film of clean oil on gasket of new filter.

6. Install filter. Turn filter clockwise until gasket makes contact with the mounting surface. Tighten 1/2 to 3/4 turn after gasket contact.

NOTE: Reservoir capacity is approximately 8.5 L (9 qt). Total system capacity with filter is approximately 9.9 L (10.5 qt).

7. Fill oil reservoir with approximately 8.5 L (9 qt) of oil.

8. Install reservoir cap.

9. Start engine.

10. Move throttle lever to the 3/4 fast idle position.

11. Unlock park brake.

12. Run engine in full forward position for five minutes and then cycle motion control levers forward and rearward several times. Check for leaks around filter.

13. Stop the engine. Check oil level in reservoir. Add oil as necessary.

Checking and Adjusting Neutral Creep

Check neutral creep with with engine running, motion control levers in the start/shutdown position, park brake off, and machine on level ground.

If the machine creeps forward or reverse while motion control levers are in the start/shutdown position, adjust the motion control lever linkages:

1. Park machine safely. (See Parking Safely in the SAFETY section.)

2. Raise seat.


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Picture Note: Z225 shown.


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Picture Note: Z425 shown. Z445 similar.


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Picture Note: Closeup of Z445 shown.

3. Remove locking pin (A) on black yoke end (B), then remove yoke end from arm (C). Turn black yoke end on rod (D) in (clockwise) to decrease forward creep and out (counterclockwise) to decrease reverse creep. Repeat procedure, as necessary, on opposite side (E). Install yoke ends back onto arms and secure with locking pin.

Adjusting Tracking

If the machine does not track in a straight line while going in full forward position, adjust the tracking:

1. Park machine safely. (See Parking Safely in the SAFETY section.)


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2. Adjust tracking:

NOTE: Tracking bolts limit top forward speed. If both levers hit against the tracking bolts, turn both bolts counterclockwise equal amounts until only one bolt contacts the lever. This will achieve maximum forward speed.

• If machine tracks to the left, turn tracking bolt (A) clockwise.

• If machine tracks to the right, turn tracking bolt (B) clockwise.

Cleaning Transaxle Cooling Fans (Z225)

c CAUTION: Avoid injury! Compressed air can cause debris to fly a long distance.

• Clear work area of bystanders.

• Wear eye protection when using compressed air for cleaning purposes.

• Reduce compressed air pressure to 210 kPa (30 psi).

IMPORTANT: Avoid damage! To ensure proper cooling, keep the transaxle cooling fins and surrounding area clean at all times. Operating the transaxle with obstructed cooling fins could cause damage due to overheating.


1. Park machine safely. (See Parking Safely in the SAFETY section.)


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Picture Note: View from rear of machine.

2. Clean transaxle fan fins (A) and around exterior of each fan with a rag, brush, or compressed air.

Checking and Replacing Transaxle Drive Belt (Z225)

c CAUTION: Avoid injury! Entanglement in a belt or sheave can cause serious injury. Stop engine and wait for all moving parts to stop.

NOTE: The transmission drive belt is self-adjusted using a spring tensioner and does not require a tension adjustment.

Checking Belt:

1. Park machine safely. (See Parking Safely in the SAFETY section.)


MX37947

Picture Note: View from rear of machine.


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2. Inspect drive belt (A) for excessive wear, damage or stretching while in position on the engine sheave, transmission sheaves, and drive belt tensioner sheave.

Replacing Belt:

1. Disconnect electric clutch wiring connector (B) from main wiring harness connector (C).

2. Remove clutch wiring harness from retaining clip (D), and lower harness and connector (C) through hole (E).

c CAUTION: Avoid injury! Components are installed under spring tension. Wear eye protection and use proper tools when installing and removing components with spring tension.

3. Remove mower deck drive belt (F). (See Replacing Mower Deck Drive Belt in the SERVICE MOWER section.)

4. Remove drive belt (A) from engine sheave (G), transmission sheaves and idler sheave (H).

• To make removal and installation of the belt easier, carefully rotate the spring loaded idler (I) counterclockwise (J), and remove belt.

5. Install belt onto engine sheave, transmission sheaves and idler sheave as shown by arrows.

6. Install mower deck drive belt.

7. Install electric clutch wiring harness back through frame hole and connect to main wiring harness. Secure harness onto frame with retaining clip.

Checking and Replacing Pump Drive Belt (Z425 and Z445)

c CAUTION: Avoid injury! Entanglement in a belt or sheave can cause serious injury. Stop engine and wait for all moving parts to stop.

NOTE: The transmission drive belt is self-adjusted using a spring tensioner and does not require a tension adjustment.

Checking Belt:

1. Park machine safely. (See Parking Safely in the SAFETY section.)


MX37946

Picture Note: View from rear of machine.


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2. Inspect belt (A) for excessive wear, damage or stretching while in position on the transmission sheave and drive belt tensioner sheave.

Replacing Belt:

1. Disconnect electric clutch wiring connector (B) from main wiring harness connector (C).

2. Remove clutch wiring harness from retaining clip (D), and lower harness end through hole (E).

c CAUTION: Avoid injury! Components are installed under spring tension. Wear eye protection and use proper tools when installing and removing components with spring tension.

3. Remove mower deck drive belt (F). (See Replacing Mower Deck Drive Belt in the SERVICE MOWER section.)

4. Remove drive belt (A) from drive sheaves and idler sheave.

• To make removal and installation of the belt easier, carefully rotate the spring loaded idler (G) clockwise (H), and remove belt.

5. Install drive belt onto drive sheaves and idler sheave as shown.

6. Install mower deck drive belt.

7. Install electric clutch wiring harness back through frame hole and connect to main wiring harness. Secure harness onto frame with retaining clip.