You usually enjoy mowing the lawn with your John Deere. However, this time is different. Your mower has begun to shake so bad you feel like you’re going to shake right out of your seat. There are many things on a John Deere that can cause your mower to vibrate.

A John Deere lawn mower can begin vibrating from worn engine mounting bolts, a bad clutch, unbalanced mower blades, spindle bearing damage, a bad pulley bearing, a worn deck belt, or debris collecting in your mower.

I’ll share what needs to be checked on your mower when you encounter a vibration problem. Take safety precautions to prevent your John Deere from starting or moving.

This includes removing the ignition key, disconnecting the spark plug boots, and setting the parking brake. Follow your owner’s manual for additional safety steps that need to be taken for your model lawn mower.

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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 John Deere Lawn Mower is Vibrating

Engine Mounting Bolts Are Loose on Your John Deere Mower

Check the bolt your engine sits on. These are bolts specifically designed to absorb vibration from the engine.

When these engine mounting bolts, also referred to as motor mounts, become worn, broken, or missing you will experience an increased vibration throughout your John Deere mower. Replace any missing or worn mounting bolts you find.

Bad Clutch on Your John Deere Mower

Your mower will use an electric or manual engagement clutch. A vibration can be felt when the ball bearing in an electric clutch fails.

If your mower uses a manual clutch with belts and pulleys, check the bushings and linkages. These can wear and fail to cause your mower to shake.

Unbalanced Mower Blades on Your John Deere Mower

John Deere mower blades must be balanced before they are installed on your mower. A balanced blade is one that has equal weight on both sides of the blade.

The blades will not spin evenly when each side is not of equal weight. This can cause a vibration when they spin at high speeds. It can also cause spindle-bearing damage.

A blade can become unbalanced when dirt sucked into the deck wears the blade unevenly. It can also become unbalanced during the sharpening process when more metal is removed from one side than the other.

Use a blade balancer to check the balance of your blade. You can also use a nail in the wall. When using a nail to check the balance, place the nail head 3/4” to 1” away from the wall.

Place the center hole of the blade onto the nail. Shave a little metal off the side of the blade that hangs lower until it sits level on the nail.

Foreign Material Around Your John Deere Mower Blade Spindle

I recommend walking the yard before each mowing to remove items that could damage the mower including rocks, toys, and branches.

While you do everything you can to prevent damage to your mower deck, you can still miss some items. It is possible for string, wire, or even a long weed to wrap around the blade spindle.

Inspect your spindles and remove any foreign objects wrapped around the spindle causing your mower to shake. Check for additional damage to the spindle housing assembly.

Bad Bearing in the Spindle Housing on Your John Deere Mower Deck

A bad bearing in your spindle housing can cause extra movement when the blade rotates. The extra movement will create an excessive vibration in the deck that can be felt through the rest of the mower.

This is often the result of a bad spindle bearing. To check for a bad bearing, you will need a heavy pair of work gloves to protect your hands from the sharp blade edges.

Grab each side of your mower blade and rock it up and down. If you find movement or hear a knocking sound because of this movement, the spindle housing assembly must be removed to check for wear. This extra movement you felt is most likely due to a bad spindle bearing.

Depending on your John Deere mower deck model, you may be able to replace the spindle bearing or you may have to replace the spindle housing assembly.

Worn Deck Belt and Bad Pulley Bearing on Your John Deere Mower Deck

A worn deck belt with extra slack can cause a vibration in your mower. Check your belt for signs of wearing. This includes cracks in the belt, a glazed shiny appearance, a loose belt, or the belt sitting deep in pulley grooves. Replace a worn mower deck belt.

Next, check the pulleys on your John Deere deck. The pulleys should be sitting flat and parallel to the deck. They should not wobble. A bad bearing in your pulley can cause your pulley to not sit level.

When the belt runs across a pulley that no longer sits secure to the deck, a vibration can be felt when the deck is engaged.

Check for a bad bearing by slowly turning the pulley by hand. Feel for a restriction and listen for a noise coming from the bearing. When you find either of these symptoms, replace your pulley.

Worn Idler Bracket or Spring on Your John Deere Mower

Over time, the spring can become weak and stretched. The hole it attaches to on the bracket can wear and become larger. These items can cause your mower to vibrate.

Replace with a new bracket and spring if you find they are worn. Also, check the bearing and bushing in the engagement linkage for wearing.

Debris Lodged in Your John Deere Lawn Mower

Debris, such as wood chips, stones, and acorns, that are stuck in your mower can cause it to vibrate and shake. Small debris can be stuck in under your pulleys, tensioner, and other areas in your mower.

Look over your mower carefully removing any objects that aren’t supposed to be in your mower. You may be surprised at how such a small item stuck in your mower can cause a big vibration.

In Summary

Performing some pre-mowing checks, routine maintenance, and regularly cleaning your mower after each use can identify problems early that can cause your John Deere mower to vibrate.

Check your mower over for loose or missing hardware, blade and spindle damage, and wearing of deck components throughout the mowing season.