How to adjust belt tension on riding lawn mower will be one of the best skills you will ever learn. You will simply need a wrench!How to Adjust Belt Tension on Riding Lawn Mower

A lawn mower can lose its belt tension, and you wouldn’t want that to happen when you need it the most.This article will guide you, step-by-step, on how to adjust the drive belt of your mower.

How to Adjust the Belt Tension for Your Lawn Mower

To adjust belt tension for your lawn mower, you will just need one thing: 

an adjustable wrench. In the case that you only have fixed-size wrenches, look for one that can be used on the screws of your garden mower. 

1. Check the Condition of the Belt of Your Riding Lawn Mower

Before you tighten the belt tension of your lawn mower, you have to make sure first that the mower drive belt is in good condition. If your mower deck belt is damaged, then you’d be better off replacing it.

Even if you adjust the belt tension of a damaged belt, it could still end up breaking. Worse, it can come off the pulleys due to damage, leaving you with a useless lawn mower.

Start the inspection by placing your lawn mower on a level surface. Turn off the lawn mower to prevent accidents.

Next, you’ll need to lower the mower deck down to its lowest settings. This will help you get a good view of both the belt and the pulleys.

Now, place your hands on the visible sections of the lawn mower belt. Run your hands along them so that you can look and feel for any damages.

If you see any damage, replace the deck belt immediately. If you don’t see any damage except for a loose mower deck belt, then proceed to the next step.

2. Look for the Spring and Bracket of Your Lawn Mower

Most lawn mower models have decks that display a swing arm, the belt, and several pulleys from the top. A tension spring should also be visible. This tension spring is attached to the swing arm and to a bracket.

You’ll need to double-check for damages. These are what you need to look out for:

  • Damages in the belt can come in the form of cracks, frays, and obvious signs of wear and tear. Worn belts slip off easily, even if they are frequently adjusted.
  • Swing arms should rotate freely. When they don’t you should apply some lubricating oil at the pivot and clean the parts of any debris that prevent rotation.
  • Springs should be ideally stretched. If it’s loose, then you need to tighten them.

Engage the blades of your lawn mower by employing the lever next to the steering wheel. Once engaged, push down on the spring and then grab hold of your mower’s belt. Even with the blades engaged, the belt should feel loose.

3. Loosen Your Mower’s Bracket Screws

Disengage the blades first before you do anything. This will make everything looser. The lack of tension will make any adjustments easier to do.

Loosen Your Mower’s Bracket Screws

After the blades have been disengaged, you can begin adjusting the tension of the mower deck belt of your lawn mower. To do this, move the bracket backward to which the spring is attached. Doing this will apply additional tension to the spring.

Take hold of your wrench and use it to loosen the screws, which are usually found at the base of your mower’s bracket. Most of the time, manufacturers have two screws attaching the bracket to the deck.

You don’t have to take off the screws, however. You simply have to loosen them.

4. Pull the Bracket Away From the Spring

Now that the screws are loose, you can begin to pull the bracket away from the spring and toward you.

Pull the Bracket Away From the Spring

Keep on pulling until you notice resistance.

5. Tighten Your Mower’s Bracket Screws

Using your wrench, turn the screws until they are tight.

Tighten Your Mower’s Bracket Screws

Ensure that they are tight enough so that the bracket does not get affected by any pressure.

6. Engage the Blades of Your Mower

Get your hands on the lever and engage the blades. This will make everything tighten up again. Next, check the deck belt of your lawn mower to see if there have been any results.

Engage the Blades of Your Mower

Ideally, the belt should feel tighter and the spring should be stretched further. This is an indication that your lawn mower belt has been tightened properly.

If you feel that the belt is still loose, go back to the third step where you loosen the screws. Repeat the process until the belt has been significantly tightened.

7. Test Your Lawn Mower

At this point, you’ll be able to see if you have made any real difference to the tension of your mower’s belt. When you feel the lawn mower drive belt loose and still slack, you may need to check the belt again.

But before you turn on your lawn mower, it’s a good idea to check the other parts of the engine. You’ll also need to note that some manufacturers have placed a belt keeper for their mowers. This contraption is placed in the mower to stabilize the belt while reducing friction.

Doing a quick check on these parts will help ensure a mower with good engine parts. Look for the spark plug, the plug wire, and the cub cadet. Once these are inspected and considered working, turn on your lawn mower.

Your lawn mower blades should be cutting blades immediately after you push the lever. You can consider the lawn mower drive belt loose if there is a whirring sound.

Look for a faster spin cycle at full speed compared to previous spins. If the speed is indeed quicker and faster than before, then the adjustment of the tension of your mower’s belt has been a success.

Otherwise, you might need to repeat the third step and tighten the belt all over again. Do this until you feel that the spin cycle is significantly faster than the previous try.

How Do You Identify the Causes of Loose Mower Belts?

To identify the causes of loose mower belts you have to know the “symptoms” that will show up. Sometimes, loose mower deck belt symptoms can show up as patches of untrimmed lawn. Other times, the riding lawn mower just doesn’t move properly.

Tightening the belt of your garden mower is one thing, but keeping it so is another. While we want our machines to last as long as we want them to, not all of them do. Here are some reasons how the belt of your mower can become loose:

– Worn Belt

Even the best belts can have their limits. When used excessively over a long period of time, mower belts eventually experience normal wear and tear.

Worn Belt

As it becomes thinner, the belt slips off.

– Damaged Belt

Sometimes, the cause is a damaged belt. The links experience factory defects or become damaged over time, which can cause the whole belt to come loose.

Damaged Belt

Usually, this is due to a product defect or an inferior product replacement.

– Stretched Out Belt

Most people won’t believe it, but metal mower belts do stretch out eventually. While metal is hard, it is still malleable and can easily deform under heat and pressure.

Stretched Out Belt

Once the belt starts stretching, it becomes too big and eventually comes loose.

– Wrong Belt Used

There are times when the belt is just too big for the mower. Most of the time, this is caused by using the wrong belt size.

Wrong Belt Used

Always refer to the owner’s manual to determine the correct belt size for your garden mower.

– Bent Belt-keepers

The pins that are alongside the pulleys are belt-keepers designed to hold the belt in place. If one or more of these pins should become bent, then the belt eventually comes loose.

– Split Plates or Brackets Below Pulleys

The pulley keepers and pulleys get the brunt of the force when the belt keeps coming off. Sometimes, they can split. When turned on, these damaged parts can cause to belt to slip off.

– Debris Buildup

Too much use can result in debris, such as sticks, grass, and dirt, building up over time. If not regularly cleaned, these can easily cause the belt to slip off or come loose.

– Safety Tips and Tricks

Operating a lawn mower can be a dangerous activity if safety precautions aren’t taken. To make sure that adjust the tension of your mower’s belt is done safely, here are some reminders:

  • Read the owner’s manual to understand how to care for and maintain your garden mower.
  • Check your mower regularly to see if there is any damage.
  • Regular mower checkups also help in preventing future repairs and damages.
  • Always turn off the engine when checking your mower.
  • Aside from turning off the engine, remove the key from the ignition.
  • Keep children and pets away when maintaining or repairing your garden mower.
  • Keep an eye on the cutting blades as they can easily cut you.
  • If there are still problems with the belt, it may be time to ask for the help of an expert.

Frequently Asked Questions

– Can You Just Simply Replace the Belt on Your Mower?

You can just simply replace the belt on your mower, yes. However, it is best to replace the belt only when there are certain signs of damage. Otherwise, you would just be replacing a perfectly good belt and wasting money.

– What Should be the Length of the Belt for my Mower?

Manufacturers produce belts with varying lengths that measure anywhere from 42 to 55 inches. Depending on your model, you will need the exact length. If you use the wrong length not only will it not work you can severely damage the machine.


Tightening the belt of your mower doesn’t have to be hard. To recap, here’s what you need to remember:

  • Check the condition of the belt of your mower for any damage.
  • Look for the parts of your lawn mower that need to be visually assessed for damages.
  • Loosen the screws and pull the bracket away from the spring.
  • Tighten the bracket screws of your mower and make sure everything is screwed on or assembled tightly.
  • Engage the blades of your garden mower and test it for performance.

Once you learn how to adjust the belt tension of your mower, you’ll never wonder again how tight should a mower deck belt be. With this article to guide you, you’ll soon be the expert in maintaining and keeping the best mower in your neighborhood.

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