Lawnflite 703 Autodrive deck belt replacement

The mower deck uses a pair of counter rotating blades designed to create a high volume airflow up through the middle of the deck into the collection chute. The routing of the deck belt is therefore not quite as obvious as it might be since it needs a crossover point to get each blade spinning in a different direction.

The belt used for the 36" cutting deck has a part number MTD 754-04075, the OEM is usually PIX, and their part number is A-75404075 - it is usually cheaper to buy the PIX part directly, rather than the MTD part.

Changing the belt

It is possible to change the belt without removing the deck from the mower - although it is slightly easier to see what is going on with the deck removed. There are two sprung idler wheels that keep the deck belt taught. These also allow enough slack to get the belt on or off if required.

Removing the belt

With the deck in place, the easiest place to get at the belt is where it goes round the main Power Take Off pulley on the bottom of the motor. With the engine off and the mower in neutral, with the blade clutch not engaged, pull a small section of belt to the underside of the PTO pulley over the rim. Now rotate the pulley manually to "derail" the belt off the edge of the pulley. Note there are a couple of narrow clearance gaps that you will need to tweak the belt through to get it clear of the pulley.

Installing the belt

Getting the new belt back on is slightly harder since the tensioner springs are quite strong. Methods that can work:

1. Approach one is the reverse of the removal process described above - using the nut on the bottom of the PTO pulley as a starting point, and then rotating the belt onto the pulley.
2. Another option is to work from the front of the mower, and reach under and grab both sides of the belt with gloved hands - that makes it easier to pull on the sprung idler wheels to get enough slack to hook the belt over the PTO pulley.
3. Using a length of timber as a leaver on one of the sprung idler wheels to free some slack

If none of the above work, then disconnect the deck from the mower - this will allow it to move forward and make it easy to get the belt on the pulley (although now you have to re-attach the deck with the tension on the belt making it a bit harder!)

Do the twist

One final complication is that the belt is a vee profile belt, and in all cases except one, needs to run with the point of the vee facing the centre of the pulley. The exception to this is the smaller sprung tensioner, which has a flat profile, and it is intended that the back of the belt will run against this pulley.

In the diagram the red edge of the belt indicates the direction of the narrow section of the vee. The blue sections indicate where a 180° twist needs to be included.

To allow the belt to face the right way, there are some 180° twists required, Moving anticlockwise, and starting from the PTO pulley, the belt goes straight to the small tensioner, and then round the left blade drive pulley. It then twists on its way to the right blade drive pulley. It continues straight through the larger tensioner pulley, and then twists once again on the return to the PTO pulley.

The deck belt routing (shown disconnected - the motor PTO pulley will go at the top)