This video provides step-by-step repair instructions for replacing the transmission on a Troy-Bilt lawn mower (model 12AVB2RQ766). The most common reason for replacing this part is if the self-driving feature is not working properly.
All of the information for this replacement video is applicable to the following brands:
Troy-bilt Lawn Mower - Model 12AVB2RQ766
Lawn Mower Transmission Assembly Replacement
Tools & Assistance Needed
"You will need a 9/16th inch socket, a 3/8th inch socket, a weight, and needle-nose pliers for this procedure, and you may need assistance."
"Before you begin, confirm the engine has cooled."
Be sure there is little or no fuel in the tank.
"For safety, detach the ignition coil wire from the spark plug to prevent the engine from accidentally starting."
Now tip the lawn mower back and use a weight to hold the handle assembly down.
"Using the 9/16th inch socket, unthread the nuts securing the two front wheels."
"Slide off the two drive gears, along with the wheel guards."
Use the 3/8th inch socket to unthread the seven lower screws securing the front transmission cover.
Unthread the two upper screws securing the cover.
Pull the wheel adjustment lever outward so you can fully detach the cover.
Remove the two drive shaft bearings.
Slide the front axle assembly off.
"Detach the belt guard, and release the belt from the drive pulley."
Use the needle-nose pliers to depress the tabs to release the drive control cable from the transmission.
Detach the end of the cable from the support.
Use the needle-nose pliers to depress the tab to release the spring insert and you can remove the old transmission assembly.
"To prepare the new transmission assembly for installation, transfer the spring and insert from the old assembly to the new one."
Position the new assembly on the support and snap the spring insert into place.
Reattach the drive control cable to the support and snap the cable into place on the transmission.
"Realign the belt on the drive pulley, and replace the belt guard."
Align the front axle assembly on the transmission support.
Slide the two drive shaft bearings onto the axle and fully insert them into the axle plates.
Make sure the bearings are positioned in the notches in the support.
Hold the axle assembly in place as you reposition the front transmission cover by first inserting the tab under the belt slot in the deck.
Make sure the drive cable is positioned in the notch in the cover.
Pull the wheel adjustment lever outward to properly align the front of the cover.
"Replace the nine screws to secure the cover, starting with the lower middle screw."
Reposition the wheel guards followed by the two drive gears.
"Align the two front wheels, and thread the nuts to secure them."
Remove the weight and return the lawn mower to its upright position.
"Reattach the ignition coil wire to the spark plug, and refill the fuel tank if necessary."
Congrats! Your lawn mower is ready for use.