Lawnflite 703 Autodrive blade clutch replacement

This article gives an overview of the replacement process for the blade / power take off clutch on a MTD / Lawnflite mower. Note that the mbasic process will be the same for many models of mower from the MTD stable of products.

The particular mower here is a 2007 model with an overall part number of 13AH483E611

Description of problem

The clutch was slipping - so that when engaging the blades, they wither failed to spin up at all, or spun up after a long delay or took a long time to achieve full speed. Sometimes when mowing they would spin down if they hit a patch of grass that was more difficult to cut.

Layout

The clutch mechanism attaches directly to the output shaft of the B&S motor. It has a long spindle and two vee belt pulleys. The top smaller pulley is a fixed pulley that is used to propel the mower. The "hydrostatic" drive is basically a belt drive system where the main drive belt is fitted slackly round the motor and intermediate drive pulleys. It passed through a pair of idler pulleys, that rotate on a platform controlled by the accelerator. With the accelerator in the idle position the two tensioning wheels are almost inline, and the belt is able to slip. As you press the peddle, the idlers counter shit in position pulling the drive belt ever tighter, reducing the amount of slip allowed.

The lower larger pulley features a clutch mechanism, and is used to provide a power take off to the cutting deck. A driver operated leaver will apply pressure to a control arm on the side of the clutch, via a spring. Pulling the arm progressively tighter.

Preparation

Remove the rear grass collector bin, and remove the grass discharge tunnel.

Drop the cutting deck to its lowest position, and disconnect the rear of the deck from the cable operated lifters.

Raise the lift mechanism to full height.

Shift the deck forward a little and disengage from the front hanger bracket.

Slide the deck out to the side.

You now need access under the mower. I drove the front of mine onto a couple of car ramps: