How To Tell If A Mower Deck Spindle Is Bad (4 Telltale Signs)

Upgraded Home Team
by Upgraded Home Team
Mowing your lawn and it does’t seem to be working effectively? There are four telltale signs that your mower deck spindle is bad. Whether it be vibration or squealing sounds, let’s take a look at the key signs that your spindle is bad.

There are different components to a lawnmower that make up its ever-changing technology. Some parts, however, remain the same and have never changed. One of those parts is the spindle which a significant part that turns the blades.

The blades on the deck are designed to give an even cut to make the yard look spectacular. If a spindle is going out, you will be able to spot the difference and even tell where it went bad. There are different ways to know if the spindle is going out.

You can tell if a mower deck spindle is bad by noticing uneven cuts, squealing, and vibration. Having bent or broken parts is another way to know if the spindle is going out. As soon as you notice these signs, it is critical to discontinue use and change the spindle immediately.

Do You Need a Mower Repair Service?

Get free, zero-commitment quotes from pro contractors near you.

What Is a Lawn Mower Deck Spindle?

Mechanics and those familiar with the parts of a mower know what a spindle is. They also know what happens when it goes bad. It is the part responsible for spinning the blades while the PTO clutch is running.

It is a part that needs to be on the maintenance list when it comes to greasing and checking. To best describe, the spindle is a part that is an axis that motions the spinning of the blade shaft. It is located on the mower’s deck and connected to each of the blades.

Mowers have one to three spindles, depending on how many blades the mower has. It connects directly to the pulleys and spins with the force of the belts turning the pulleys. If there is a problem with the spindle, then the blades will malfunction.

The Four Signs the Spindles are Malfunctioning

Most mechanical parts will give off warning signs before they break entirely. If any of these signs are present, it is critical to change the spindles immediately to prevent further damage. Damages may occur to the deck, blades, or the lawn.

1. The Lawn Will Have Uneven Cuts

The first and most noticeable problem when the spindles go out is the yard is cut uneven. If the spindle goes of the axis, the blade will not move even with the others. When this happens, the lawn can become damaged and uneven.

It can take months before the damage is repaired, especially if the blade cuts into the ground. The grass can get burned or killed by being uprooted during the cut. The common causes are the bearings loosened or the spindle shifted.

2. There Will Be a Squealing Noise

The spindles on riding mowers are larger than other mowers. Mowers with two or more blades may experience the squealing when the spindles are fixing to give. The common cause is wear and tear on the bearings, or the spindle is broken and needs to be replaced.

3. If There is Vibration and Buzzing Noises

Buzzing noises are expected when the spindle is going bad. This happens right before the vibration occurs. When the vibration happens, it is usually the deck, but it is with such force, the entire mower will shake.

The common issues are the same as the squealing noises. In troubleshooting, try to change a frozen wheel first. If the vibration or buzzing sound is ongoing, continue to change the spindle.

4. Broken or Bent Parts Can Mean the Spindle is Worn

It can sometimes become visible when the spindle is broken or bent. When it reaches this depth, the blade may stop or hit the other blades. It can even hit the deck and cut through it if it is hit enough times.

There will be loud cracking noises that are impossible not to notice. When the grass is cut uneven, and the other parts begin to fail, it is time to replace the spindle.

Do You Need a Mower Repair Service?

Get free, zero-commitment quotes from pro contractors near you.

How To Replace a Mower Spindle Step By Step

Now that the signs have been established, there is no doubt the spindle needs to be replaced. These are the tools that you will need to gather before starting the DIY project and the steps to follow.

  • Hydraulic jack
  • Concrete blocks or jack stands
  • Safety glasses
  • Work gloves
  • Flat-head and a Phillips screwdriver
  • Deep socket wrench set
  • A brand-new spindle

Step 1: Park the Mower on Level Ground

Find a comfortable spot that is level and dry so that you can work underneath the deck. The ground must be level and safe to perform the task. Some ideas for the perfect spots are in a driveway, carport, garage, or under a patio.

Step 2: Prepare the Mower for Replacing the Spindle

Here is a list to follow in preparing the mower. It is a priority to put safety first, which is the main focus of these procedures.

  • Let the mower cool down for a couple of hours if it has been in operation for a while.
  • Remove the key from the ignition and engage the parking brake.
  • Place blocks or boards underneath the back tires, so the mower does not roll backward.
  • Remove the spark plug wire and the spark plug for added security.
  • Drop the deck to its lowest setting.
  • Put the working gloves on and jack up the mower, putting the stands to let the mower sit on them. Check to ensure the tires remain blocked before getting under the mower.

Step 3: Remove the Blade

The blade with the bad spindle needs to come off first to get to the spindle. Here is the list of how to remove the blade.

  • Get a board to keep the blades from turning and use the deep socket wrench to remove the bolt.
  • You will then see the bolts holding the spindle in place. Remove those bolts with the socket wrench.
  • Some spindles are locked with a pulley. In this situation, remove the belts and the pulley. This process will give complete access to taking the spindle out.

Step 4: Removing the Spindle

Once the bolts are removed, the spindle should easily come down from the deck. Take caution when removing the spindle, so it does not fall on you. Ensure your safety glasses are on from the beginning due to falling debris.

If more than one spindle is the problem, repeat steps three and four.

Step 5: (Optional) Replace the Bearings

You may find in some cases; the spindle is still usable. If this is the situation, the bearings may only need to be replaced. Keep in mind; this is not always the situation.

This step should be skipped and move on to step six if the entire spindle needs to be replaced. This is the list of how to replace the bearings.

  • Once the spindle is removed, separate the casing and remove the bearings.
  • Place the new bearings in place of the old ones. Ensure they are installed correctly, and they are not loose and moving around.
  • If needed, use a rubber mallet to put the bearings in place. Some may be difficult to do by hand.
  • Put the spindle back on the shaft, putting the spindle in its proper position and bolting it back on the deck.

Step 6: Put the Spindle Back On the Deck

This is the list of how to put the spindle back in its place.

  • Put the spindle back on the shaft, pushing it up to the base of the deck.
  • Bolt everything back up and ensure the spindle is on tightly with no play-action whatsoever. Some decks have three bolts; some have four holding them in place.

Step 7: Put Everything Back In Place

Reinstall everything by following this list.

  • Put the pulley and the belt back on if you had to remove them. Ensure everything is tight and the belt still has the proper tension. You should only be able to pull the belt a fourth of an inch, no more.
  • Double-check the pulley and spindle are tight after putting the belt back on.
  • Put a board in place to hold the blades and put the blade back on. Repeat the steps if more than one spindle was replaced.
  • Replace all spindle covers and any other parts or protective devices you may have decided to remove.

Step 8: Test the Mower

After lowering the mower, remove the blocks and replace the spark plug and wire. Take the mower out and test it to make sure everything is working correctly.

Related Guides

Upgraded Home Team
Upgraded Home Team

We are a team of passionate homeowners, home improvement pros, and DIY enthusiasts who enjoy sharing home improvement, housekeeping, decorating, and more with other homeowners! Whether you're looking for a step-by-step guide on fixing an appliance or the cost of installing a fence, we've here to help.

More by Upgraded Home Team