How to Replace Riding Mower Blades

Park on a flat surface, engage the parking brake, and remove the key. Disconnect the spark plug wire(s).

Lower the deck to its lowest setting. For easier access, you can also drive the front wheels up onto ramps or use a floor jack.

Locate the blade bolt(s) underneath the deck — one per blade. Most riding mowers have 2 or 3 blades.

Wedge a block of wood between the blade and the deck housing to prevent rotation while loosening.

Remove the blade bolt by turning counterclockwise. These are typically very tight (50+ ft-lbs). A breaker bar or impact wrench helps significantly.

Remove the blade and any washers or spacers. Note the order of hardware and blade orientation (cutting edge and discharge side).

Install the new blade with the cutting edge oriented correctly — the lift wing (the bent-up portion) should point toward the deck (up).

Reinstall all hardware in the correct order. Torque the blade bolt to manufacturer spec — typically 35-55 ft-lbs.

Remove the wood block. Reconnect the spark plug wires. Raise the deck to your desired height.

Start the mower and listen for any unusual vibration — which would indicate a blade is unbalanced or improperly installed.