How to Tell If Mower Deck Spindle is Bad?

All the components must be in good shape for a lawn mower to cut grass effectively. A spindle is one of the most vital components of a lawn mower since it holds the blades that are responsible for mowing. Therefore, it is important to keep an eye on it just to ensure it functions well at all times.

A bad deck spindle will not only damage your mower but your lawn too. As such, you need to realize if your mower deck spindle is faulty to avoid wreaking havoc on your turf of green. Truth be told, knowing the indicators of a bad spindle in your mower will save you a lot of dollars and keep your grass safe from damage.

Luckily, it is easy to tell if a mower deck spindle is bad. This article has all the information you need on a damaged deck spindle including how to tell if a mower deck spindle is bad. So, read on and have fun mowing.

How to Tell If Mower Deck Spindle is Bad? – (Solved)

There is a big distinction between how a good deck spindle and a faulty one operate, So, trust me, if your mower deck spindle is bad, you will quickly notice. To start with, the most common thing you will notice is an irregular noise when operating your lawn mower.

Besides, an uneven cut on the grass also signifies a bad mower deck spindle. On top of that, you can also notice irregular vibrations and a squeaking belt in your mower. When your mower’s spindle is failing, you may also notice twisted or broken pieces. These are some of the most significant symptoms of a damaged mower deck spindle.

When you notice the above-mentioned symptoms, you should replace the spindle immediately to avoid any more damage.

Typically, lawnmowers come with one to three spindles depending on whether the mower has a single blade, twin blade, or three blades. Remember that the blades function to provide a consistent cut to your lawn making it look nice and appealing.

On the other hand, the mower deck spindle directs the blade shaft’s rotation. Thus, the spindle has to be functioning well for the blades to spin otherwise; the whole lawn mower cannot function.

How Do I Know If My Spindles Are Bad?

When it comes to rotating parts in lawn care equipment, even the high-quality and strongest of materials can fail. Spindles are responsible for spinning the mower blades and as such, they are exposed to a lot of external forces.

Lawnmowers, like other mechanical equipment, give warning signs when they have a faulty component. When you notice these signs in your lawn mower, it is time to replace the damaged spindles with new ones.

As we have already seen, a faulty mower deck spindle is hazardous to the blades, deck, and even your precious lawn. The following signs will help you determine if your spindles are bad:

  • Uneven Mowing:

The most obvious sign that you will observe when you have a bad mower deck spindle is an uneven cut on your lawn. If the spindle goes off its axis, the particular blade held by this spindle will mow unevenly with the others.

This leads to an uneven cut that can potentially damage your lawn. Note that if things go badly, the blade can even cut the ground damaging the root system of your grass. Believe me, it may take months to repair this kind of damage or worse the grass will die off.

  • Unusual Vibrations from Your Lawn Mower:

I’d be lying if I said a lawn mower does not vibrate but the vibration of a faulty spindle is something else. If your lawn mower has a bad spindle, you will notice extremely unusual vibrations when operating your machine.

A mower deck spindle is held in its axis with well-functioning bearings. But if the mower has bad bearings then the spindle will not sit straight within its housing.

As a result, the spindle will be free to move around the additional room in its housing causing lots of movement as the belt rotates. This extra movement causes unusual vibrations as you run your mower.

Besides, if your mower deck spindle is bent, the blades will have an awkward rotation that is likely to cause loud vibrations.

It is easy to tell when these vibrations occur, you will feel them on the deck – it feels like the entire lawn mower is shaking. This is a clear indication that your mower deck spindle is bad and needs changing.

  • Twisted, Bent, or Broken parts:

If a failing spindle goes unnoticed over time, the blade may end up breaking off or clashing with the other blades. Besides, a faulty spindle may cause the blade to cut the mower’s deck.

If this happens, you will hear loud shattering sounds coming from the deck. At times, a bad mower deck spindle can result in the mower’s blade, belt, and pulley completely falling off.

  • An Unfamiliar Noise:

Another clear indication that your mower deck spindle is failing is an unfamiliar noise. Simply put, after using the mower over time, the bearings are subject to wear and tear. Damaged bearings allow the spindle metal to come into contact with its metallic housing thus causing an unnerving sound.

I doubt anyone loves that metal-on-metal sound. What’s more, this may cause the spindle to have fractures or even break down.

How Do I Know If My Mower Deck Spindle Is Bent?

Sometimes, the mower deck spindle may not be bad but just bent. Note that the two can be confusing. On one hand, a bad spindle is mostly a result of worn-out bearings where the spindle does not sit on its axis but rather has more room for extra movement.

On the other hand, the bearings of a bent spindle are well-functioning; the only problem is that the spindle does not sit straight on its housing because it’s bent. Since the spindle is connected to the mower’s blades, a bent spindle will also affect the grass cut.

The most common way to tell whether your mower deck spindle is bent is by checking how the blade cuts your lawn.

With a bent spindle, the blade will no longer be straight and thus cut the grass at a sloped angle. If you notice saw toothing on the lawn, it is a result of the difference in cutting heights between the blades in your lawn mower and it means that you have a bent spindle.

You can also do a quick test to confirm that your mower deck spindle is bent. First, remove the belt from the pulley and give your mower a spin.

Pay close attention to how the spindle functions, it should be straight and spinning freely. On the contrary, you’ll know that your lawn mower spindle is bent if it spins from side to side.

Should A Mower Deck Spindle Spin Freely?

The spindles in lawnmowers are the components that hold the blades. When you engage the deck of your mower, a pulley system drives the clutch which rotates the spindles and the blades.

For efficient operation of your machine, the deck spindle should spin freely. Remember, like most other rapidly moving parts of a machine, mower deck spindles must operate smoothly at all times.

How Do You Check Spindle Bearings On A Deck?

The spindle bearings in a lawn mower allow the deck’s pulley to spin. When you use your lawn mower, the bearings are prone to wear and tear. Thus, with time, you may notice squealing sounds coming from your lawn mower. This sound is mostly an indicator of worn-out spindle bearings. To check the spindle bearings on a deck.

Step 1:

Remove your mower deck from your lawn mower. This process varies depending on the model of lawn mower that you have.

Step 2:

Remove the belt off the mower’s pulley. This leaves the spindles and the pulley free from the belt’s obstruction.

Step 3:

Spin the pulley and listen to squeaking, grinding, or squealing sounds. If none, the spindle bearings are in good shape. Ensure that you replace faulty bearings before using your lawn mower.

How Do You Test A Lawn Mower Spindle?

To test whether your mower deck spindle is bad, first remove the belt from the pulley. Next, give your lawn mower a spin. In this case, since the spindle and the pulley system are free from the belt obstruction, you can freely observe how the spindle works.

First, look at the spindles’ rotation. A well-functioning spindle should spin freely without producing unfamiliar noises. Secondly, observe how the spindle sits on its housing, it should be straight and turn nicely within its axis. Otherwise, it is a cause for alarm.

How Often Should You Grease Mower Spindles?

As we have already seen, spindles are rapidly mowing components when the lawn mower is in use. As such, they are subject to wear and tear and thus need regular lubrication through greasing. Thankfully, applying grease to your mower spindles is a hassle-free process.

With the ideal grease for your mower model, a grease gun, a screwdriver, a wrench, and some protective gloves, you are good to go. Nevertheless, you might still face some difficulties like how often you should grease the mower spindles.

For commercial lawn mowers that are in regular use, you should grease the spindles once per week or even once per day depending on your work volume. On the other hand, for residential mowers that handle smaller mowing tasks during the mowing season, you can grease them once or twice per season.


If you are looking at how to tell if a mower deck spindle is bad, the article has it all. Read the article to know if your deck spindle is bad or bent, how to test your lawn mower spindle, and how often you should grease mower spindles among other things.

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Victoria Peterson

I am a passionate gardener who wants to help you create and maintain your dream yard. I know that it can be daunting to take on a project like this, but I am here to help. I have been gardening for years and have learned a lot along the way. I want to share my knowledge with you and help you create the perfect yard for your home.

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