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My CC mower is a 2012 Z-force-S 48 model. I recently replaced the drive belt, idler pulleys, and fans after the old drive belt slipped off the crank pulley and I discovered the belt guard on the right drive unit was bent down, all the blades on that side fan were gone, the left idler pulley had bad bearings, and the belt was missing some chunks of the V. I also replaced the blades and the blade belt.

After all the new stuff was on, I mowed down our grassy hill/road and at the bottom the mower would not come back up the hill. It spun the left tire digging into the dirt but the right tire did not seem to move. It didn't matter whether the steering was turned or straight ahead - only the left wheel dug in, so I figured the new belt must have come off the right side driven pulley so I pulled out the transmission by-pass rods at the back, and pulled it slowly back up to the house. Once there I removed the cover plate at the front of the engine and discovered that the drive belt was still on all the pulleys correctly. I checked the parking brake lever and it seemed to move things underneath as it should, so I released the transmission by-pass rods, started it again, released the parking brake, and it seemed to drive OK again - it would zero turn both directions and go backward and forward.

Jacking up the back and crawling under, the parking brake levers seem to work OK clamping the little disk brakes in park and letting them loose when released, and the only odd thing I found was that the levers on the drive units that are pulled by the transmission by-pass rods to let you roll it by hand do not have any return springs and are just left loose when the rods are released. The rods have compression springs on the forward ends to pull the by-pass levers toward the rear, but there is no positive connection or spring to return the levers when the rods are released - Should there be?

I am pretty sure I didn't have a brake locked up, so I am at a loss to figure out why just the left wheel was driving and whether the right wheel was simply not driving or may have been locked somehow. The transmission by-pass lever seems the only logical cause, but I've never had it do that before and I sure don't want to get stuck at the bottom of the hill again.

And BTW, I remember several posts where folks said their dealers removed the rod from the parking brake that moves the idler pulley arm and slackens the drive belt and told them the drive belt should always be tight - even in park. Anyone care to comment on that pro or con?

No, bypass valves do not have return springs.

Drive pumps should be running all the time or it will cause premature pump failure.

BlazNT said:

No, bypass valves do not have return springs.

Drive pumps should be running all the time or it will cause premature pump failure.

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I didn't quite understand about drive pumps running all the time. I figured whether or not to relieve the drive belt tension with the parking brake lever had more to do with the belt possibly coming off a pulley. So you are saying the pumps should be running even when the machine is stationary with the parking brakes on? Would that be because the fans need to keep turning?


BTW, I reset the parking brake pad clearance to .030" (even thought they seemed to be set OK as in disk tight with the brake on and loose with the brake off) and tried the mower again and all seemed normal again. I am pretty sure a brake was not locked up when only one wheel was driving, and the only change I made was to pull the transmission by-pass rods and slowly pull the machine up the hill to the driveway and then re-engage the transmission drives again. I can only guess that one had somehow disengaged at the bottom of the hill and moving the rod got it back engaged. In any case I mowed for two hours and it zero-turned both ways and pulled back up hill OK.

I had left the fan/pulley cover off to observe drive belt, and I think I may leave it off permanently so I can blow all the dirt out that collects in the center of the fans when I clean after mowing. I am surprised Cub did not have a cover on the individual fans to avoid dirt building up in those deep, cupped centers.

philwarner said:

I didn't quite understand about drive pumps running all the time. I figured whether or not to relieve the drive belt tension with the parking brake lever had more to do with the belt possibly coming off a pulley. So you are saying the pumps should be running even when the machine is stationary with the parking brakes on? Would that be because the fans need to keep turning?


BTW, I reset the parking brake pad clearance to .030" (even thought they seemed to be set OK as in disk tight with the brake on and loose with the brake off) and tried the mower again and all seemed normal again. I am pretty sure a brake was not locked up when only one wheel was driving, and the only change I made was to pull the transmission by-pass rods and slowly pull the machine up the hill to the driveway and then re-engage the transmission drives again. I can only guess that one had somehow disengaged at the bottom of the hill and moving the rod got it back engaged. In any case I mowed for two hours and it zero-turned both ways and pulled back up hill OK.

I had left the fan/pulley cover off to observe drive belt, and I think I may leave it off permanently so I can blow all the dirt out that collects in the center of the fans when I clean after mowing. I am surprised Cub did not have a cover on the individual fans to avoid dirt building up in those deep, cupped centers.

Click to expand...

Heat kills. Keep it a cool as possible.