Why Does My Zero-turn Mower Cut Uneven?

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Are you frustrated that your zero-turn mower cuts uneven? You’re not alone. Every so often, a landscaper will experience this problem. Sometimes you may be partly to blame for the jagged cut, but mostly, there’s usually a problem with the ZTR. Below I’ll walk you through the main reasons why your z-turn leaves strips of uncut or uneven grass.

What Causes a Zero-turn Mower to Cut Uneven?

Here is a list of the common zero-turn mower problems and the possible solutions to ensure a clean and evenly cut lawn.

  • Dirty Deck

The deck of your ZTR accumulates dust, debris, and grass clippings over time. You need to inspect and clean your mower deck regularly. Otherwise, debris accumulation may affect your deck’s air circulation, resulting in an uneven cut.

  • Low Tire Pressure

If you are mowing during early spring, a drop in temperature may cause your z-turn’s tires to have low pressure. When this happens, the zero-turn mower’s deck may dip on one side, causing it to cut unevenly. Thus, always check the tire pressure before you begin mowing.

  • An Uneven Deck

Does your zero-turn mower cut unevenly? Is your deck clean and tire pressure perfect? Perhaps, your deck is the problem. From time to time, you may accidentally hit on an obstacle or unexpectedly run into something. Such incidences cause your z-turn mower to bounce and slope.

An uneven deck means that one side of the blades, too, will be higher than the other. Regularly inspect your deck’s levelness. And should you notice that it’s sloping, fix it before you can start mowing. Better yet, call a professional to level it for you.

  • Damaged Deck

Regardless of how much you try to level the z-turn mower’s deck, all your efforts are in vain if it is damaged. Inspect your ZTR regularly to identify any bent decks and replace them to achieve an evenly cut. 

  • Mowing Too Fast

If you’re driving your zero-turn mower too fast, the mower blades and deck may not keep up. It gets worse if you’re mowing an uneven lawn. Traveling too quickly on an uneven yard not only leads to a rough cut but also causes too much bouncing. This bouncing movement may end up causing more problems, as it may lead to an uneven deck.

As we have seen above, an uneven deck will cause your zero-turn mower to cut unevenly. Thus, always establish the optimum speed that allows the optimum performance of your mower blades.

  • Damaged or Blunt Blades

Do you want to achieve a clean, even, well-manicured lawn? Unfortunately, it will be impossible to accomplish this when using dull or damaged blades.

A nicked, blunt, or warped blade ends up tearing the grass instead of giving the golf lawn cut you need. To solve this, replace any damaged blades and sharpen your mower’s blades a minimum of three times per year.

Also, note that an incorrectly installed or unbalanced blade may leave a strip of uncut grass between rows. Ensure that all blades are installed correctly, balanced, and attached securely to your mower.

  • Blade Size

Have you recently replaced your mower blades, but your zero-turn mower now cuts even? Your new cutting blades are either too short or small for your specific machine. Unfortunately, you’ll have to purchase new blades for your z-turn, this time being keen to ensure that you’ve picked the right size for your mower.

  • Mowing in one Pattern

If you mow a lawn in a particular pattern and direction season after season, the grass eventually becomes accustomed. The grass will automatically fall in the direction it is trimmed and may never stand upright again.

When the grass is bent, the mower blades find it more challenging to lift the grass, which leads to uneven cut lawns. To prevent this from happening, ensure you mow lawns in a pattern that crisscrosses the previous one.

  • The Cutting Height is too Low

Every residential zero-turn model has a recommended maximum height. For most, it is usually at 4”. In case the grass on your lawn is overgrown, trim the overly tall grass before mowing. Also, ensure that you do not cut too much grass at once. Doing so can clog your mower deck, resulting in an uneven cut.

  • Inadequate Overlapping

If you make sharp turns or fail to overlap your paths enough, your ZTR leaves some of the grass untouched. To avoid this, try as much as possible to mow in straight lines. Plus, always overlap your mowing rows from 2- 4 inches to clear any strips of uncut grass.

  • Failing Deck Pulleys and Worn Drive Belt

The deck pulley and drive belt are designed to work hand in hand to rotate the mower’s cutting blades for a smooth, even cut. If either of the parts is worn or broken, the blades may spin unevenly or even fail to turn.

Damaged deck pulleys may also cause the blades to rotate during operation. The solution is to fix or replace worn belts and faulty pulleys.

  • Low Engine Speed

As a general rule of thumb, always aim to run your zero-turn mower’s engine at full throttle. That’s because if the engine speed is too low, the blades won’t spin quickly enough, resulting in uncut or unevenly cut grass.

But remember, as I pointed out earlier, running your engine at full speed has its downside. Grass clippings, dirt, and debris may clog your deck, resulting in an uneven cut. Be sure to clean your mower deck frequently to prevent this from happening.

In Conclusion

There are many reasons why your zero-turn mower cuts unevenly. The most common ones include a damaged or blunt blade, clogged or an uneven mower deck, low tire pressure, and inadequate overlapping.

Most of these causes are preventable by regularly inspecting your zero-turn mower and replacing any broken parts. Also, play your role as the operator. Ensure you’re driving the mower at its optimum speed, adequately overlap your mowing paths, and avoid making extremely sharp turns.