Mowing your lawn isn’t always the most comfortable task especially if your ground is uneven. You bounce around when riding on your mower especially when you’re mowing uneven ground.

This shaking can become more pronounced when you develop a vibration in your Gravely mower. It may even feel like you’re riding a jackhammer!

A Gravely lawn mower vibration can develop when the mounting bolts are not securely placed under the engine; the ball bearing in the clutch fails; the mower blades are unbalanced or damaged, or the deck belt is worn.

A vibration may also be the result of bad bearings in the pulleys or spindle housings, damaged brackets or debris stuck in the mower.

Before working on your Gravely mower and mower deck, follow all safety procedures as outlined in your owner’s manual.

This includes removing the ignition key and disconnecting the spark plug wires to prevent your mower from starting. Make sure your mower does not move while working on it to avoid injury.

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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 Why Your Gravely Lawn Mower is Vibrating

Worn or Missing Engine Mounting Bolts on a Gravely Mower

The engine vibrates as it runs. Some of the vibrations are absorbed by the engine mounting bolts. These are bolts that sit underneath the engine. They are often referred to as motor mounts.

Look for these bolts and make sure they are in good condition and securely in place. Tighten any loose bolts and replace any that are worn, broken, or missing.

If you own a Gravely push mower, check the engine bolts when you feel excessive vibration once you engage the mower blade.

Failing Clutch on a Gravely Mower

The ball bearing may fail on an electric clutch causing your mower to shake. In a manual engagement clutch, the bushing and linkages can fail to cause a vibration. A manual clutch is used with belts and pulleys.

A push mower does not use a clutch. It uses a lever to engage the blade. This lever needs to be checked for loose or worn components.

Incorrect or Unbalanced Gravely Mower Blades

Installing the wrong blades or unbalanced blades on your Gravely mower can cause a vibration.

Wrong size Gravely mower blades:

Not every mower blade that has the correct center hole size and blade length will fit your Gravely lawn mower. I prefer using OEM (Original Equipment Manufacturer) blades so I know I’m running a good quality mower blade with the correct dimensions.

If you choose to use an aftermarket lawn mower blade, I recommend first laying it on top of an OEM blade to make sure it is a match before placing it on your Gravely.

Unbalanced Gravely mower blades:

Blades can become unbalanced and no longer spin evenly under the deck. They will begin to wobble as they spin. At very high speeds, you will feel a significant vibration.

An unbalanced blade is a blade that is heavier on one end of the blade than the other. There are a couple of different items that cause a mower blade to become unbalanced.

• Normal Use: Dirt rotating under the mower deck can wear the blades unevenly.
• Blade Sharpening: Too much metal is removed from one end of the blade than the other.

Make sure your Gravely blades are balanced using a blade balancer before you install blades on your mower. Find out more about sharpening and balancing your blades here.

Material Wrapped Around a Gravely Mower Blade Spindle

Wire, string, and even long weeds can wrap around the blade spindle causing your Gravely mower to start vibrating. These are hard items to see when you’re mowing so they are hard to avoid.

Inspect the spindle and remove any items that are wrapped around it. Once this is done, check your spindle and spindle housing for further damage.

Damaged Spindle Housing Components on a Gravely Mower

A bent spindle or worn bearings in the spindle housings can cause the blades to wobble when you engage your blades causing vibration in your Gravely mower deck.

Before you check your spindle housing for damage, put on a good pair of work gloves to protect your hands from the sharp edges of the mower blade.

Grab a hold of each end of the mower blade and rock it up and down. What you’re doing is looking for any movement. You may hear a knocking sound from the extra movement.

If you feel movement, remove your mower blade and spindle housing. Inspect for bearing or spindle damage and repair.

Worn Mower Deck Belt on a Gravely Mower

When a mower deck is worn and stretched leaving some slack, the belt will not sit securely around the pulleys.

This extra slack as the belt moves around the deck can cause your Gravely mower deck to vibrate. Replace a worn belt if you find it is stretched, cracked, or has a glazed appearance.

If the belt appears in good condition, make sure it is routed around the pulleys correctly and the tension is adjusted to remove extra slack.

Bad Pulley Bearings on a Gravely Mower

A vibration in the mower deck can be felt through your Gravely mower when you are using bad pulleys. The bearings can fail to cause the pulleys to not sit securely flat and parallel to the deck.

When the pulleys are not sitting parallel to the deck and have some movement to them, the mower will shake as your belt runs around the pulleys.

Check each pulley to make sure it is securely attached to the deck and doesn’t have a wobble to it.

You don’t want a lot of movement in the pulley where one side of the pulley sits higher off the deck than the other. When this happens, you most likely have a bad bearing on the pulley.

Find a failing bearing by slowly rotating each pulley by hand. Feel for a restriction and listen for bearing noise. If you experience either of these, your bearing must be replaced.

Note: Some pulleys will only use sealed bearings. In this case, you will have to replace the pulley and bearing assembly.

Worn Idler Bracket & Spring on a Gravely Mower

A loose or worn idler bracket and spring can make your Gravely mower shake. The hole in the bracket where the spring attaches can wear larger and the spring can become stretched. When this happens, you will experience a vibration.

Replace a worn idler bracket or spring. Check the bearing and bushing in the engagement linkage and replace them if you find they are worn.

Debris Lodged in a Gravely Mower 

Check your Gravely for small debris stuck in the small crevices of the mower. When mowing the lawn, your mower kicks up the debris that can collect on your mower. Something as small as a wood chip can cause extreme vibration in your mower.

Remove your spindle covers and clean off your deck regularly. Debris can collect under your pulleys and cause them not to sit flat and parallel to the deck.

Debris buildup can also affect the tensioner where it is no longer able to keep proper tension on the belt. This will cause extra slack and your mower deck to shake.

Look every part of your mower over carefully and remove any items that are lodged in your mower. It is best to clean your Gravely after each mowing to keep it free of debris not only to prevent vibration problems but also corrosion from moisture in the debris.

Need help with cleaning procedures? Check out “How to Clean Your Mower for Best Performance“.