A Bobcat zero-turn has an uneven cut due to low tire pressure, worn mower deck belt, dull, mower blade, bent mower blade, unbalanced mower blade, bad spindle bearing, bad pulley bearing, or damaged deck shell.
Operating your Bobcat mower with a low engine speed or fast ground speed can also cause an uneven or bad cut.
Take safety precautions to reduce the likelihood of injury. This includes removing the ignition key and spark plug wires. Wait for all items to stop moving and wear appropriate safety gear.
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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 Bobcat Mower Cut Quality Problems
| Problem | Result | Solution |
|---|---|---|
| Scalping | Close cut in areas of the lawn | Low tire, uneven lawn, unlevel deck, deck height too low |
| Step Cut | Ridges in the lawn | Unlevel deck, bent mower blade, low tire, spindle damage, wrong blade installation |
| Streaking | Strips of uncut grass | Worn blades, dull blades, clogged mower deck, incorrect mowing paths, mowing too fast, engine speed is too low. |
| Stringers | Patches of uncut grass | Worn blades, dull blades, clogged mower deck, mowing too fast, engine speed is too low. |
Bobcat Mower Uneven Cut: Problems & Solutions
| Causes | Solutions |
| Worn mower blade | Sharpen or replace blade |
| Low tire pressure | Add air to correct levels |
| Bent mower blade | Replace mower blade |
| The blade is incorrectly installed | Install blade and hardware correctly |
| Clogged mower deck | Scrape the deck |
| The deck is not level | Level the deck |
| Damage to the spindle or spindle housing | Replace damaged spindle or housing |
| Bad deck belt | Replace worn belts |
| Bad pulley | Replace a bad pulley |
| Engine speed is too low | Run mower at full throttle |
| Ground speed is too fast | Adjust speed for mowing conditions |
| Incorrect mowing paths | Overlap paths |
| The deck shell is damaged | Repair or replace mower deck shell |
| Unlevel Yard / High Spots | Use a smaller deck mower / Roll your lawn |
Bobcat Zero Turn Mower Has an Uneven Cut (12 Reasons)
1. Low Tire Pressure
When you encounter a cut problem, you may immediately assume the problem lies in your mower deck. Before you begin adjustments to your Bobcat mower deck, look at your tire pressures first.
A low tire can throw off the level of your mower deck causing it to give you an uneven cut. Don’t skip checking the tire pressure before checking your deck’s level and making adjustments.
Steps to check and correct the tire pressure:
- It’s best to check the tire pressure when the tires are cold.
- Remove the valve stem cap.
- Place a tire pressure gauge on the stem to check tire pressure.
- Check Bobcat’s recommended tire pressure PSI.
- Add air using an air compressor to match the PSI recommended.
- Place the cap back on the stem.
2. Worn or Dull Mower Blade
A Bobcat mower blade can become so worn that strips of uncut grass are left in your yard. This is caused by dirt and debris being sucked into the mower deck and wearing down the metal of the blade.
There isn’t any way to prevent wearing. It is a normal occurrence.
Inspect the mower blade for:
- Wearing of the blade sail
- The blade sail is the high side of the blade. The part that helps create air movement as the blade rotates under the deck.
- The air movement and area under the deck create a suction that stands the grass tall for an even cut.
- The blade must be replaced when the sail is thinner than the center of the blade.
- Worn blade ends
- May leave strips of grass between the blades.
- Replace a blade that has rounded ends.
- Dull blade edge
- Will not precisely cut the grass.
- May end up just beating up and tearing the grass. The tips of the grass may turn brown a day or two after mowing.
- Sharpen a dull blade if it is still in good overall condition.
- Replace a blade in bad condition or has gouges in the blade edge that cannot be fixed during the sharpening process.
3. Mower Blade is Bent
A slightly bent or severely bent blade can cause a bad and uneven cut. A blade can bend when you impact a hard object with your Bobcat mower.
Sometimes the impact is so great you can feel the jolt and hear the grinding of metal. You know something went wrong and you need to check your deck for a bent blade and other damage.
Other times, the impact isn’t as significant so you don’t even think about checking for a bent Bobcat blade. When you are experiencing a bad cut, it is important to not only check your blades’ wearing condition, but you must also check for blade damage.
There are a couple of methods you can use to check for a bent mower blade. One method requires the removal of your mower blade while the other does not.
When checking for a bent blade, it’s a good time to check for spindle housing damage before removing a blade. For that, read the instructions in the next section.
Check for a Bent 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 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 Bobcat 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 Bobcat blade will put people, pets, and structures in the area at risk of injury or damage.
4. Mower Blades Are Not Balanced or Installed Correctly
Mower blades that are not correctly balanced and installed can cause your Bobcat mower to cut unevenly. It’s important to follow the procedures in your operating manual to correctly install your blade with the correct hardware.
Before installing your mower blade, it must be balanced. What this means is the blade needs to weigh the same on one end of the blade as it does on the other.
A blade can become unbalanced by uneven wearing from normal use. It can also become unbalanced during the blade sharpening process. This happens when more metal is shaved off one side than the other.
How to balance the mower blades:
- Use a blade balancer to check the balance of your blade.
- Place the blade on the balancer.
- Shave a little metal off the heavier side of the blade.
- Use a nail mounted on the wall to check blade balance. The nail head should be sticking out of the wall about 3/4″ to 1″.
- Place the center of the blade into the nail head.
- Remove metal from the side of the blade that is hanging lower until the blade sits level.
5. Spindle is Damaged or the Spindle Bearing is Bad
When a component in your spindle housing is bad, there will be an extra movement where your blade will begin to wobble when turning. At high speeds, this can cause a significant vibration and cause a bad cut.
How to check for spindle housing damage:
- Wear heavy gloves to protect your hands from sharp blade edges.
- Grab both ends of a blade and rock them up and down. You are checking for any extra play or movement.
- Listen for a knocking noise as you may hear a noise when your blade is moving up and down.
- If you feel or hear either of these, remove the spindle housing and check the spindle and bearing for wearing or damage.
6. Mower Deck is Plugged with Grass Clippings
You can’t avoid it. Every mower deck gets plugged with grass clippings, dirt, and other debris. When this happens, the area under the deck that is needed to create good airflow and suction is minimized.
This will give you a bad cut when there isn’t good suction to lift your grass tall for cutting.
In addition to a bad cut, the collection of dirt and grass clippings can put extra strain on your engine causing it to work harder and possibly shut down.
To avoid this, scrape your mower deck regularly. Wet grass tends to clump and clog your mower deck faster than dry grass.
Tire tracks also show mower prominently in wet grass. Avoid mowing wet grass if possible. If you must, make sure you scrape your deck following your mowing.
You can try using silicone or Teflon spray to prevent the amount of debris that collects under the deck.
While there is nothing on the market today that will prevent all grass clippings and dirt from sticking to the underside of a Bobcat deck, this product can help minimize the amount of sticking.
7. Mower Deck is Not Level
When your mower deck sits higher on one side of the deck than the other, you will get an uneven cut. To correct this, follow your Bobcat operator’s manual to measure and make the necessary adjustment to level the deck from side-to-side.
You will also need to follow the manual to determine the correct rake and make any adjustments necessary. The rake is the pitch of the deck from front to rear.
Adjustments and measurements vary on the model of your Bobcat deck. This is the reason you must consult your manual for correct procedures.
8. Worn 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 Bobcat 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 Bobcat 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 Bobcat 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.
9. Running Your Mower with a Low Engine Speed
The blade tip speed affects the quality of the cut. Your Bobcat lawn mower needs to be running the engine at full power to give your deck enough power to rotate your blades at high speeds.
Always run your mower at full throttle when using the mower deck.
If you are running at full throttle, but your mower isn’t giving you the power you once had, bring your mower to your local Bobcat dealership or small engine repair shop to be looked at.
10. Running Your Mower at Fast Speeds
Mowing conditions must be factored in when running your Bobcat mower. Your engine will experience heavier loads when you use your Bobcat to cut thick, tall, or wet grass.
When operating in these conditions, slow down so your mower is better able to handle the load and provide you with better-cut quality.
Moving too fast through your lawn can cause your mower to push over grass and not allow it the time to sufficiently stand grass tall under the deck for a precise cut.
11. Incorrect Overlapping
I know what it is like to be short on time and try to space out your paths as wide as possible to reduce the number of paths you need to create to get the job done.
I also know that when I try to do this, I always find areas where I didn’t overlap my cuts enough leaving strips of uncut grass.
If your mower is new to you, it may take a few mowing to be able to gauge how much overlap you need to get a good cut.
12. Mower Deck Shell is Damaged
The deck shell can become damaged when you accidentally hit an obstruction like a post, tree, or building.
A tweaked or damaged Bobcat deck shell can cause a bad cut. You must repair your deck shell or replace it if it can’t be repaired.
When replacing the deck shell is your only option to repair your mower deck, it is a good idea to get a price on a full mower deck replacement.
Sometimes the difference in price between replacing a deck shell and replacing the full deck isn’t that significant.
This is especially true when you add the cost of labor involved in swapping deck components from one deck to a new deck shell. It’s always good to be informed and consider the cost of the repair with the age of your mower to make a good decision.
13. Lawn is Uneven
An uneven yard with high spots from molehills or other reasons can cause your mower to scalp those areas. Mowers work best on leveled lawns. While this may be the case, many people don’t have the luxury of having a completely flat lawn.
Sometimes a lawn roller will help even out your lawn and get rid of some high and bumpy areas. A lawn roller is a weighted roller.
When mowing areas with steep declines and ditches, a Bobcat mower with a wide format deck will scalp the yard. These wide decks are unable to flex and bend with the dips in the yard.
You just end up with an uneven cut. It is best to use a small format mower in these areas like a small push mower.