How to Tell If Mower Deck Spindle Is Bad?

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Have you ever heard of a lawnmower deck spindle? It is an essential part of every lawn mower deck where the blade is. And it has the vital task of ensuring the blade spins.

When the deck spindle fails, for whatever reason, the mower will start functioning incorrectly. In that case, you will have to either fix it or replace it.

Here, we’re going to teach you how to know when a mower spindle is bad. Then, you’re going to learn how to fix it or replace it as needed.

Want to learn how we can help you out? Then take a peek below!

What is a Lawn Mower Spindle?

First, let’s give you a heads-up about this spindle.

In short words, you can say it is the part that works as an axis for the blade shaft to spin.

Without the spindle, the lawnmower wouldn’t be able to cut because the blade wouldn’t be able to spin. 

The spindle connects directly with the pulleys, receiving the force that helps the blade spin. When it is broken or bent, there’s a high chance the blade will malfunction.

That’s why it is so important to check whether it is bad or not. Next, you’ll learn how to check it. 

4 Signs You Have a Bad Lawn Mower Deck Spindle

There are many ways the mower deck spindle can break. So, there are many different symptoms you may experience while working with a mower with a lousy spindle.

These are the 4 signs you may experience: 

Uneven Cuts

mower deck spindle

When the spindle gets off its axis, then there’s a high chance the blade won’t move evenly. Sure enough, this causes the cuts to be uneven and damage your lawn. As someone who makes sure the grass is always leveled (which is hard) – you may get extremely frustrated with this.

The reason this happens? The spindle bearings loosened up, or the spindle moved out of place. Sometimes, it is not adjusted correctly. Either way, you’ll have to fix it up.

Squealing 

In riding mowers, the spindle tends to be a little larger than most mowers. This causes it to make loud squealing sounds when it goes bad. There’s a chance the spindle is broken, or the bearings are worn out.

Buzzing Noises & Vibration 

Similarly to the squealing, if the mower starts to make buzzing noises while mowing your grass, it probably means it has a bad spindle. Likewise, you’ll feel how the mower begins to vibrate out of nowhere. 

If you’ve checked and changed a stuck wheel or any other part, then you already know it is probably the spindle. 

Bent & Broken Parts

If the spindle looks bent or broken, then it needs to be replaced. You will feel how the blades start to move unevenly and cut your grass in a disorganized way.

In some cases, the blade won’t spin at all or instead make loud cracking noises. Either way, it means your spindle needs some replacement. 

Step-by-Step Guide: How to Fix a Mower Spindle

Now that you have a better idea when the mower deck spindle is done, and you need to get it out – we’re going to help you actually do that. 

Follow the guide below to make this happen. 

Tools You’ll Need:

mower deck spindle

  • A hydraulic jack
  • Jack stands / wood blocks
  • A pair of work gloves
  • A flat-head/Phillips screwdriver
  • A socket wrench
  • A new spindle 

1. Look for the Right Place

First and foremost, you need to look for a place where you can work comfortably and safely with the mower.

You’ll be lifting it and working from below, so you’ll need to be in a place that makes it possible.

We usually recommend flat floors with enough space around, like patios, large shacks, garages, and/or driveways. 

2. Prepare the Mower

After finding the ideal place to work with the mower, then you can proceed to prepare it. Follow these steps:

  • If you’ve been using the mower recently, then let it cool down for a few hours. The engine tends to get hot, alongside its moving parts.
  • While it cools down, you should take the key off the ignition and activate the brake if it has any. Then, block the tires, so it doesn’t move.
  • If you want to take it a step further, then remove the spark plug and empty its gas tank. This will make the operation even safer. 
  • In case you have a riding mower with a removable deck, then remove it instead and proceed to the next step without lifting the mower. You will have to get the safety locks out and unfasten the spindle from the pulleys.
  • If you have a riding mower without a removable deck, then proceed to lift the mower up with a jack. Put on the gloves first. Then place some jack stands or wooden blocks below so the mower can rest on them, and you can work more safely. 

By now, you’re ready to get the blade out and reach the spindle.

3. Discover the Spindle

if mower deck spindle is bad

Discovering the spindle will let you remove it and replace it. But first, you’ll have to get the blade out

  • First, grab the socket wrench and remove the bolt that attaches the blade to the mower. Carefully get the blade out the way (from the deck).
  • Now proceed to where the spindle is located. Look for the fastener or bolts around it. You need to unfasten them with a socket wrench.
  • If the spindle is locked with a pulley, then remove the pulley and belts as well. 

Now you will have almost direct access to get the spindle out.

4.  Remove the Spindle

With free access to the spindle and the fasteners and bolts all out, then you can proceed to remove it.

  • Three bolts are usually holding the spindle to the deck. Get them off with your socket wrench. Be careful as the spindle may fall after getting the fasteners/bolts out.
  • If your mower has several spindles, then repeat the process accordingly.

Now you can decide whether you want to fix the spindle or install a new one.

5. Replace the Bearings (Optional)

In case you saw the spindle with bearing issues, then you can replace the bearings only instead of the whole piece. Here’s how:

  • The spindle will be assembled via various bolt and screws. Get them out using the right tool.
  • Now separate the casing of the spindle and remove the internal bearings accordingly.
  • Grab the new bearings and place them on the spindle. Install them correctly, so they don’t move around.
  • Some bearings may need some pressure to get in place. Use a rubber mallet or something similar to press them in.
  • Finish by reconnecting the spindle to the shaft and putting the spindle together once again. Use the screws and bolts accordingly.

This will give you a renewed spindle that is ready for some mowing. 

6. Install the New Spindle

In case the spindle is not recoverable, you’ll have to change it up. We recommend doing things when you see any bent or broken part in the piece. 

Do this to install a new spindle:

  • Grab the spindle you replaced the bearings on (or the new one) and place it where the old was one. 
  • Tighten it up using the3 nuts and bolts. Be sure the spindle fits tightly in the deck and doesn’t move.

Now the spindle is installed, so you only need to put the rest of the mower in place. 

7. Put Everything Back Together

With the spindle back on the deck, you will have to re-install everything so you can start using it again. Here’s how:

  • If you had to remove the deck from the mower, then begin by re-installing it. 
  • Proceed by putting back the belt and pulleys. Be sure to tighten everything well so the machine can work seamlessly next time.
  • Tighten the pulley and spindle well with the nuts. This will get the spindle in place and ensure you can start using the machine once again.

After placing the spindle cover and other parts, then you’re ready to test the machine,

8. Lower the Mower & Test

how to tell if mower deck spindle is bad

Remember the spindle making it impossible to mow your lawn comfortably? Well, now you can do it effortlessly.

  • Lower the mower using the hydraulic jack. Remember to remove the jack stands and/or wood blocks after securing it with the jack. 
  • Then place it on the grass. And start the mower and test it out to see how it works. Drive it around to check how well it cuts. 

If you don’t experience any type of vibration, buzzing, or performance issue – then you’ve successfully replaced its bad spindle.

Also read: How to Tune Up Your Lawn Mower

Fix Your Lawn Mower Deck Spindle Now!

The mower deck spindle can be a pretty tricky part to fix. But once you know it is the spindle, then there’s no better way to proceed than to replace it or repair it.

So, do you feel like the spindle on your mower is causing trouble? Then check it following this guide. And if it needs replacement – then follow our guide accordingly. You won’t regret it.

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