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13 Reasons a Cub Cadet Lawn Mower Has a Bad or Uneven Cut

You take time out of your busy week to make sure your yard is looking its best. Usually, your lawn looks good once you get done mower with your Cub Cadet, but this last time was different. The cut looks terrible and you’re not quite sure where to start to fix the problem.

A Cub Cadet mower can have a bad or uneven cut when the mower deck is plugged, not level, or the shell is damaged. Damaged spindles, bad bearings, bad pulleys, dull blades, and worn deck belts can affect your cut.

Many things can affect your cut and leave you with a bad-looking yard. I have put together a list of items so you can hopefully find out what is causing your bad cut.

Why Your Cub Cadet Lawn Mower Cuts Uneven

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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

Types of Cub Cadet Mower Cut Quality Problems

ScalpingClose cut in areas of the lawnLow tire, uneven lawn, unlevel deck, deck height too low
Step CutRidges in the lawnLow tire, unlevel deck, bent mower blade, spindle damage, wrong blade installation
StreakingStrips of uncut grassWorn blades, dull blades, clogged mower deck, incorrect mowing paths, mowing too fast, engine speed is too low.
StringersPatches of uncut grassWorn blades, dull blades, clogged mower deck, mowing too fast, engine speed is too low.
Cub Cadet Cut Quality Problems

13 Reasons Your Cub Cadet Cuts Uneven

1. Cub Cadet Mower Blade is Worn or Dull

Extremely worn blades can leave strips of grass on your lawn when. When the blades are very worn, they should be replaced.

If your blades are just dull, you may not be able to see any significant problems with the cut until a couple of days later. Dull blades beat up the grass and leave it bruised.

This bruising will slowly turn a brown color so you won’t notice it right away. Sharpen your blades if they are in good enough condition. Replace them if they are not. You can find more information on how to change and sharpen your Craftsman blades here.

2. Cub Cadet Mower Blade is Bent

A bent mower blade on your Cub Cadet can give your lawn an uneven cut. Take a look at your blade. Sometimes it is quite obvious your blade is bent, especially if you hit something solid.

Other times it is hard to tell. Even a slight bend can cause your cut to be uneven so you will want to take measurements to verify your blade is not bent.

Check for a Bent Cub Cadet Blade by Removing the Blade:

  • Park your mower on a flat-level surface.
  • Remove the ignition key and spark plug wires. Wait for all parts to stop moving.
  • Safely gain access to the underside of your mower deck.
  • Remove the blade and place it on top of a new mower blade.
  • Replace the mower blade if the old blade does not match up and there are gaps.

Check for a Bent Cub Cadet Blade Without Removing the Blade

  • Park your mower on a flat-level surface.
  • Remove the ignition key and spark plug wires. Wait for all parts to stop moving.
  • Measure one side of the blade from the ground to the blade tip and record the measurement.
  • Rotate the blade 180 degrees and measure the other side of the blade from the ground to the blade tip and record the measurement.
  • If the two measurements are greater than a 1/8” difference, you must replace your mower blade.

Never attempt to straighten your mower blade

It may be tempting to try to straighten your Cub Cadet blade to save a little money. The metal of the blade is compromised when you straighten it making it weak. This weak area is likely to crack and cause the metal to break off your blade.

This gets extremely dangerous when your blades are rotating at very high speeds. Straightening a blade will put people, pets, and structures in the area at risk of injury or damage.

3. Cub Cadet Mower Blades are Installed Incorrectly

The high side of the blade, known as the sail or fin, must point up when installed on your Cub Cadet deck. Installing your blades upside down will not only hit the ground and tear up your grass, it can also damage the blade spindle.

Make sure your blades are balanced before you install them. Unbalanced blades can cause an uneven cut and send a vibration through your mower. Read more about mower blade installation here.

4. Cub Cadet Mower Deck is Plugged with Grass

When your Cub Cadet deck gets plugged with a bunch of grass and dirt, your mower won’t give you a good cut. The design of the mower deck along with the air movement created when the blades spin forms a suction under the deck.

This suction lifts the grass to stand tall while the blades pass by and cut the grass. When the deck is plugged and it can’t create that suction so the grass doesn’t get cut evenly.

You must check and scrape your deck periodically. You’ll have to scrape it more often when cutting wet grass because wet grass tends to stick to the mower deck and leave clumps in your yard.

Some Cub Cadet owners choose to use a silicone spray meant for mower decks to prevent debris from sticking to your deck. This spray helps but will not prevent all of the grass from sticking. You will still need to scrape your deck, but hopefully, not as often.

5. Cub Cadet Tire Pressures are Not Correct

Owners often overlook their tires when they have an uneven cutting problem. It seems obvious to focus on your mower deck when looking for a cutting problem, but something as simple as a low tire can cause the deck to not sit level. Check your tire pressures are correct.

6. Cub Cadet Mower Deck is Not Level

If your lawn mower tires are set to manufacturer specification and it is not causing your deck to sit unevenly, then it is time to move on to checking the mower deck height.

With your mower parked on a level surface, measure the distance between the ground and the base of the mower deck on all four corners of the deck. If the measurements are not the same, follow your owner’s manual for instructions to level your deck.

7. Cub Cadet Blade Spindle is Bent

Check the blade spindles for a bent spindle or a damaged bearing. Again, make sure your spark plug boot is removed and the key is not in your ignition switch for safety.

With a pair of heavy gloves, grab a hold of each end of your mower blade. Rock the blade up and down and check for movement.

If you feel movement or hear a knock, you have a bad bearing in the spindle housing or a bent spindle. You will need to repair or replace the spindle housing.

8. Bad Cub Cadet Mower Deck Belt

A worn or stretched belt will fail to move around your pulleys at high speeds. This can slow down the blade revolutions and cause your mower to give you a bad cut.

Check your Cub Cadet belt for signs of wearing. This includes cracking, shredding, or a shiny glazed appearance.

A belt that sits deep into the grooves of your pulleys is also a sign of a worn belt. Replace with a new Cub Cadet belt when you find any of these conditions.

9. Bad Pulley or Pulley Bearing

Next, move on to checking your pulleys. A good pulley should be secure, sitting flat and parallel to your Cub Cadet deck.

When the bearing in a pulley goes bad, it can cause movement in the pulley and cause your pulley to shift from side to side when your deck is engaged.

How to check for a bad pulley:

  • Slowly rotate your pulley by hand. Feel for any resistance and listen for a noise coming from the bearing.
  • Grab ahold of both sides of the pulleys and rock it up and down. A good pulley should sit securely on the deck.
  • If you notice resistance, hear bearing noise, or feel excessive play in the pulley, the bearing or pulley assembly should be replaced.

Sometimes you can only replace the bearings and other times you must replace the pulley assembly. This varies by model.

10. Your Cub Cadet Engine Speed is Too Low or Ground Speed is Too Fast

You must run your engine at full throttle whenever you have your mower deck engaged. Your mower deck takes a lot of power to run and you need to make sure your engine speed is at full throttle.

You must also adjust your ground speed when mowing thick, tall, or wet grass. Cutting grass in these types of conditions puts extra work on your engine so slowing your groundspeed will reduce the load on the engine.

Making multiple cuts will help reduce the load on your mower too. Make the first cut at a higher deck setting followed by another cut at a lower setting.

When your engine and deck are unable to handle the load on the mower, it may not provide a good cut. Mowing too fast can also cause your mower to not be able to create a good suction and end up pushing over some grass.

11. Incorrect Overlapping Path with Your Cub Cadet

Sometimes the cutting problem is the fault of the operator. When mowing paths up and down your lawn, you need to overlap each pass so you don’t miss any sections of grass and leave strips of grass in the lawn.

12. Cub Cadet Mower Deck Shell is Damaged

A deck shell can get tweaked by running your mower into objects like trees, rocks, and other hard surfaces. The deck shell is formed to create a suction to give you a good cut. If the deck has been damaged, your cut could also be compromised.

13. Your Lawn is Uneven

When your lawn is uneven and bumpy, your mower deck can scalp the lawn. For a nice-looking cut, it will help to roll your lawn to smooth it out.

In Summary

Taking good care of your mower deck and inspecting it periodically for damage or failing parts will help prevent cutting future problems. Take extra care when operating around obstacles and ensure all toys, rocks, and other objects are removed from your yard before cutting.

Still Having Problems with Your Cub Cadet Mower?

If these tips haven’t solved your problem or if you are experiencing a different problem with your mower, check out my guide showing the most common issues and solutions: Common Cub Cadet Problems.

Here you’ll find the causes of issues like the mower not starting, a bad cut, a vibration, or a smoking problem. I include solutions along with links to more in-depth information.

George Wentzel

Thursday 11th of May 2023

Two year old LT46 Cub Cadet is leaving a single row of cut grass on the left side. I've used mulching blades with and without the plug from new and have just recently installed the original blades to see if that would make a difference but it hasn't.

Powered Equipment Team

Thursday 11th of May 2023

Since you mentioned you tried two sets of blades and have the same problem, I'm assuming the blades are not bent. I suggest making sure the deck is level from side-to-side. (Check the tire pressures first). Place the mower on a flat level surface and measure from the ground to the blade tip for both the left blade and right blade. Use the left adjustment rod to make the adjustment required to level the deck.

Then make sure the pitch (front-to-rear) is correct. Typically the front of the deck will sit 1/4"-3/8" lower in the front than the rear of the deck.

Another thing to check is damage to the blade spindle.

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