Reasons Your Cub Cadet Mower is Vibrating

You run your mower at least once a week to keep up with your growing grass. You notice something is different with your mower this week. Your Cub Cadet is shaking badly and you need to find the culprit of the problem. A vibrating mower could mean you have some worn parts or debris buildup.

A Cub Cadet Mower may vibrate when the engine is missing an engine bolt or the bolts have become loose. A failing clutch, unbalanced mower blades, worn deck parts, and debris lodged in your Cub Cadet can also cause your mower to start vibrating.

I’ve put together a list of items you need to look at when troubleshooting a vibration problem in your Cub Cadet.

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Follow all safety instructions provided in your equipment operator’s manual prior to 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.

Reasons Your Cub Cadet Mower is Vibrating

Take Safety Precaution to Prevent Cub Cadet Mower from Starting 

Before beginning to check over your Cub Cadet, it is necessary to take safety precautions to avoid injury. Do not skip this step because you don’t want your mower to start or the blades to engage while you are working on it.

Turn off your mower and remove the key from the ignition if the mower uses a key. Remove your spark plug boot for safety. Note: your Cub Cadet may use two spark plugs.

Check Engine Mounting Bolts on Your Cub Cadet 

Look at the engine mounting bolts, also known as motor mounts, to ensure they are tight. These bolts are designed to reduce the vibration felt through the mower when the engine is running. Any bolts that are missing broke or worn must be replaced.

On a push mower, you need to check the engine bolts if you experience a vibration in your mower once you engage your Cub Cadet blade.

Check the Clutch on Your Cub Cadet 

You will find an electric or manual clutch used on Cub Cadet mowers. These clutches can fail causing vibrations. An electric clutch can have a ball bearing failure while a manual engagement clutch, with belt and pulleys, can have a bushing and linkage failure.

No need to look for a clutch on your push mower as it won’t have one. You will have a blade engagement lever though that you need to check.

Inspect Your Cub Cadet Mower Blades 

Next, move on to your mower deck. Check your Cub Cadet mower blades as a number of factors can cause vibration from your blades.

Wrong size Cub Cadet blades:

All blades don’t fit every mower. For example, a mower blade for a 52” mower deck might fit some 52″ decks, but it won’t fit every 52” mower deck. You must have the correct center hole and blade length. Blades may have slight variations that may not work on your mower.

If you are not purchasing original equipment manufacturer (OEM) Cub Cadet blades for your mower, note that every aftermarket mower blade with the correct center hole size and blade length may not actually work on your mower.

I’ve found this to be true over many years of matching up aftermarket blades to OEM blades.

Unbalanced Cub Cadet blades:

An unbalanced blade can cause your deck to shake. The shake can be so severe you’ll be able to feel it in the operator’s seat. A blade can become unbalanced when it is worn more on one side of the blade than the other side from sand and other debris in your yard.

Your blade may also not be properly balanced after you sharpened it. You could have removed more metal from one end of the blade throwing off the balance of the blade. Read more about sharpening and balancing your Cub Cadet blade here.

Incorrectly installed Cub Cadet blades:

Your blade needs to have the correct components, such as washers and bolts, to mount to the spindle housing. Refer to your operator’s manual or a parts diagram to verify the parts needed to install your mower blade.

These parts must be installed in the correct order. Missing any of these pieces or installing them in the wrong order can cause your blades to wobble and vibrate your Cub Cadet.

Check for Foreign Material Around Blade Shaft 

You may take the necessary steps to make sure your yard is free of toys, debris, and other materials before you begin mowing, but it doesn’t always mean you missed something. 

Your mower can pick up items that wrap around the mower blade shaft that can cause your mower vibration. 

It’s important to inspect your mower deck for damages. Look at the top of the blade and check to see if there is any foreign material wrapped around the blade shaft such as wire or string. 

If you find any items, remove them and check to make sure this didn’t cause any further damage to the blade shaft, also referred to as the spindle. 

Check for Bad Bearings in your Cub Cadet Spindle Housing 

Bearings can go bad in the spindle housings on your Cub Cadet which can cause your mower blades to wobble when your blade is engaged.

To check for bad bearings in your housing, grab a hold of each end of the blade wearing a good pair of work gloves to protect your hands from the sharp edges.

Rock the blade up and down checking for any movement. This movement is a good indication the bearing in your housing is bad.

While you are doing this, listen for a knocking sound as this is also a sign the bearing is bad. When you feel movement, or hear a noise, you will have to replace the bearing.

You may be able to replace only the bearing or you may have to replace the whole spindle housing assembly. This varies with the deck model.

Check Your Cub Cadet Deck Belt and Pulleys 

Gain access to the top of your mower deck so you can check your Cub Cadet belt and pulleys. First, check your mower belt for wearing or shredding. If you find your belt has a shiny glazed appearance, you need to replace it.

When the belt is stretched or has a lot of slack in it, it can cause vibration. Find instructions on replacing your Cub Cadet belt here.

Another thing that can cause a vibration when your belt isn’t sitting securely on the pulleys is bad bearings or brackets. Check the bearings in your pulleys by slowly turning each pulley.

Feel for resistance and listen for bearing noise to determine if you need to replace your pulley.

Check the idler bracket and tensioner spring for wearing in addition to the bearing and bushing in the engagement linkage. When your parts are not secure and there is wearing, your Cub Cadet can vibrate.

Check out my article on reasons your Cub Cadet belt keeps coming off your mower. Many items that cause your belt to come off are also a cause of your vibrating mower.

Check for Debris Lodged in Your Cub Cadet Mower 

Debris gets kicked up when mowing. The debris, like wood chips, stones, and acorns, can get lodged in various parts of your mower causing a vibration. Check under the pulleys on your mower deck.

When items get stuck under the pulleys, the belt can cause a vibration as it runs around the pulley.

Even the smallest little items can cause your mower to start shaking. Look every part of your mower over carefully and remove any items that are lodged in your mower.

It is best to clean your Cub Cadet after each mowing to keep it in good condition. Need help with cleaning procedures? Check out “How to Clean Your Mower for Best Performance“.

More Cub Cadet Problems & Solutions

As an owner of a lawn mower, you are guaranteed to run into problems over the life of the lawn mower. I have put together a list of the most common Cub Cadet problems & solutions to give you a guide when identifying the cause of your problem.

You never know when you’re going to run into more problems with your mower. Make sure you read and add this guide to your favorites: “Common Cub Cadet Mower Problems“.