Fixed: One Side of a Zero-Turn Mower Not Working (Reasons & Solutions)

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I’ve had the pleasure of operating countless of zero-turn mower units, and these are truly a game-changer when it comes to achieving that perfect lawn. But, I’ve been there when one side of the mower just stops working, and it’s downright puzzling.

Drawing from my firsthand experiences and expertise, let me guide you through the potential reasons for this hiccup and share some tried-and-true solutions to get it back on track.

Overview of Possible Reasons and Corresponding Fixes

Possible ReasonsSolutions
Unmatched Tire CompressionCheck the tire gauge
Freewheeling Rod OverridesInspect the rod displacement and hydraulic status
Dragging BrakeAdjust the brake cable tension or release and rebuild the brake 
Stripped SplineReplacing the spindles 
Adjustment of the TractionAdjust the traction accordingly or get expert help
Bad or Old DampersReplacing the dampers and springs 
Air Pressure in the Hydrostatic MotorReleasing excess air pressure from the motor 
Deck Belt IssuesTighten the deck belt
Dull or Broken BladeReplace the blade with a new one

9 Reasons Why One Side of Your Mower Isn’t Functioning

Reason #1: Unmatched Tire Compression on Either Side

Most mowers have a single-cylinder engine, so the right side of your machine has more weight and resistance.

mower tire

In most cases, this may lead to your mower’s tires or wheels having unmatched compression. As you know, it’s important that your machine is well-balanced to function properly and avoid risks while mowing and for you to avoid untoward lawnmower injuries.

How to Fix

If the tire pressures are different on each side, it can cause one side of the mower to engage less than the other. To fix this problem, you must inspect if both tires have the same pressure using a tire gauge.

Once you verify that they’re unmatched, you must inflate the tires with the necessary pressure.

But what if your riding lawn mower blades won’t engage? Read this article guide for troubleshooting tips!

Reason #2: The Freewheeling Rod Overrides

The freewheeling rod is located near the blade control lever. It allows you to disengage the blade without shutting off the engine and works seamlessly when the rod is properly inserted. 

mower freewheeling rod

When this rod is damaged or bent, it can cause issues with the function of your mower. 

How to Fix

Always look at the freewheeling rod on either side of your lawn mower. It could be bent or damaged. And don’t forget about the hydraulic motors.

Start by checking the fluid level and then the filter, especially on the weaker side of the mower. If you spot any problems, it’s best to replace those parts right away. Alternatively, a simple adjustment might prevent any overriding.

Reason #3: Dragging Brake

The brake holds the blade in place when starting your mower. If this brake is not working properly, it can cause your blade to drag on one side. 

fixing mower dragging brake

Also, if the piston gets stuck inside the brake pads, it could cause them to seize or get misaligned. Single-piston calipers may also seize due to this issue.

How to Fix

This can be done by removing the tire. Use a single-C clamp [1] to exert force and release the pad for either sliding pins or seized caliper pistons. 

Even if you can free a stuck brake, it’s still possible that it will seize again. The reason why it became stuck in the first place is due to corrosion. But it will take a long time before it can be dislodged.

Alternatively, you can fix a dragging brake by adjusting the brake cable tension. You can find instructions on how to do this in your mower’s instructions manual. 

Reason #4: Stripped Spline

The spline is a small piece of metal connecting the blade to your mower’s shaft. If this spline is stripped, it can cause your blade to wobble on one side. 

mower stripped spline

The torque and speed of the zero-turn mower can affect the condition of the pulley. Eventually, these little components will get stripped away. So a weak or worn-out spline can prevent the zero-turn one side from working properly.

How to Fix

Change the spindles by loosening the three-bolt assembly cover. Then, use a ½-inch wrench to remove the covering from the socket.

Remove the belt using the same wrench. Then loosen the pulley and lower the belt using a cheater bar and socket wrench. Lastly, use a 1 ⅛-inches wrench to detach the nut on top of the spline within the spindles. 

Reason #5: Adjustment of the Traction

The traction adjustment is off on one side, causing the blade to stop spinning when engaged. When both of the throttles are pushed forward at the same time, one of the wheels can transfer more power than the other. This leads to the mower pushing toward the weaker side.

lawn mower tire

How to Fix

If one side of a mower starts to slip, it might be due to the traction needing adjustment. I’d recommend checking the user’s manual specific to your model for the nitty-gritty. It can get a bit complex, so seek advice from an expert when unsure.

A little tip from my experience: Lowering the tire pressure can sometimes enhance traction. And if you’re dealing with hilly terrains, consider using larger tires; they’ll help you avoid those sharp turns and sudden stops.

Reason #6: Bad or Old Dampers

These dampeners are designed to prevent excessive loads on the pumps and improve the efficiency of the mower drive system. When the units return to a neutral state, the control arms are pulled back by springs.

mower bad damper

As a result, your lawn mower will pull to one side when accelerating. 

How To Fix

You will need to replace the dampers with new ones as the easiest fix to this problem. And I recommend changing the springs, too. This is because the steering arms might not be pushed back properly after the new ones have been installed.

Reason #7: Air Pressure in the Hydrostatic Motor

When you’re using your lawn mower, you might experience cavitation in the hydrostatic system. This is caused by the buildup of air forming a fluid, allowing an air pocket within the hydro system. As a result, your mower will be weaker on one side. 

mower hydrostatic transmission

How To Fix

Follow these steps if there’s air pressure in your mower’s motor:

  1. Free the hydro. To disengage the drives, pull or push the rods on both drives.
  2. Take a seat on the mower and increase the throttle to maximum speed. 
  3. Make sure that the hydros are properly disengaged. You can switch off the mower once you’re ready to do so.
  4. After engaging the forward drive, hold for a couple of seconds. Then, reverse and repeat the reverse and forward movements several times to remove the air from the motors and bleed the hydrostatic drive. After that, turn off the engine.
  5. After lowering the jack, apply the brake and get the mower back on the ground. Then, engage the hydros and remove the chocks.
  6. Check your hydro fluid levels. If the level is low, add hydro fluid to it.
  7. Finally, do a test run to see if it now works properly.

Reason #8: Deck Belt Issues

Another issue that can cause your lawn mower not to work correctly is the deck belt. It helps to rotate the blades, so if it’s not working properly, your mower may stall or yield to one side. 

cub cadet deck belt

How To Fix

A common problem with deck belts is that they become loose over time. To fix this problem, you will need to tighten the deck belt. Depending on your mower model, you can do this by adjusting the idler pulley or drive belt tension.

But if the drive belt is already old and it already wears out, you may need to replace it for better results. 

Also Read: Lawn Mower Cord Cannot Be Pulled: How to Fix

Reason #9: Dull or Broken Blade

One last issue that can cause your lawn mower to have problems is a dull or broken blade. Blade issues will prevent your lawn mower from functioning correctly. If all one side of the blade is already dull, chances are, the grass you mow will pile on one side of the mower. 

mower blade replacement

How To Fix

A dull or broken blade is one of the most common problems with lawnmowers. To fix this problem, you can sharpen your lawn mower blade without removing it or replace the blade with a new one.

Are Zero-Turn Mowers Beneficial?

From my time spent caring for lawns, zero-turn mowers are truly a cut above when it comes to handling grass and leaves. They mulch remarkably faster than your average riding mower. What sets these mowers apart is their design for speed; you’ll be wrapping up your mowing chores in no time.

And, speaking from experience, the ergonomic design and the comfort of the seat are game changers. They significantly reduce fatigue and make the mowing experience a whole lot more comfortable.


Now, you won’t have any problems fixing or identifying the issue when one side of your zero-turn mower is not working. 

Remember, there can be a myriad of reasons causing the issue. I’ve always found that regular checks on your mower play a crucial role in staving off such problems. These machines are truly exceptional in making lawn care a breeze, so it’s only right that we give them the maintenance they deserve.

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Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You’ve probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.

Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.

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