How to Replace the Key on a Drive Shaft of a Toro Mower

The driveshaft key is a piece of metal that slips into a groove cut into the side of the driveshaft. The key acts as a lock to keep the blade and driveshaft pulley from spinning on the driveshaft. If the key strips because of excessive force applied to the blade, such as hitting a tree stump, you must replace the broken key with a new one. New Toro lawnmowers eliminate the driveshaft key and use a star shaped hole in the blade that slips over a star shaped shaft. Older Toro lawnmowers utilized the driveshaft key to hold the mower blade in place.

Wrench set
Pliers

Instructions

- 1
  Turn the Toro mower on its side so the air cleaner faces upward. This prevents gas from siphoning into the air cleaner.
- 2
  Remove the bolt that holds the mower blade onto the driveshaft on the bottom of the mower; use a wrench.
- 3
  Pull the mower blade off the drive shaft.
- 4
  Pull the key, which is a rectangular piece of metal approximately 1-inch long from the groove cut into the side of the driveshaft. Use pliers to remove the key if the key sticks inside the shaft. If the key stripped, it is common for it to stick to the shaft.
- 5
  Place the new key into the slot on the drive shaft, then slide the mower blade over the shaft. The hole in the center of the blade has a square notch cut into it to accept the key. Rotate the blade until the notch lines up with the key. Slide the blade over the key.
- 6
  Secure the bolt to the driveshaft to lock the blade onto the shaft.

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