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How to Tighten a Drive Belt on a Craftsman Riding Lawnmower, step by step

Ever witnessed your Craftsman lawnmower not mowing properly or leaving patches of uncut grass? A loose drive belt might be the very reason. Luckily, the entire process is relatively easy, and all you’ll need for the adjustment is just a socket wrench. If you’ve never performed self-maintenance on your Craftsman lawnmower before, then don’t worry as we dissect this information for you in a step-by-step approach.

How to tighten a drive belt on a Craftsman riding lawnmower, step by step:

  • Step 1: Test the tension in your existing lawnmower drive belt
  • Step 2: Inspect the components on the mower such as the pulleys, belt, spring, and swingarm and check for any damage
  • Step 3: Pull back the clamp holding the cable and tighten it so that the spring attached to it is stretched
  • Step 4: Start the engine and engage the blade lever to check for the belt operation after adjustment

Drive belts are components that connect the engine’s transmission shaft to the transaxle pulley and are responsible for the transmission of torque and power to the blades. It is situated underneath the mowing deck in case of riding lawnmowers.

The belts usually wear out after continued use. Due to elongation in their tensile cords, drive belts have been known to become loose with time. Most often, the remedy is a replacement. However, in cases when elongation isn’t much, you can always adjust the belt tension, and we are looking at that in this article.

The article covers all the steps needed to tighten the drive belt in case of your Craftsman lawnmower. I will also provide a brief overview of some frequently asked questions regarding drive belts and lawnmowers. Stay tuned.

Troubleshooting and Adjusting the Drive Belt on a Craftsman Riding Lawnmower, step-by-step:

The steps that need to be followed for fixing the Craftsman lawnmower drive-belt are mentioned below:

● Step 1: Test current drive belt for operation:

Before we dig into it, we first need to see whether the current drive belt is worth tightening or not. Most Craftsman models have a blade engagement lever next to the steering wheel. After the cutting deck is lowered to the ground, the lever engages the blades to make contact with the grass and perform their function.

To see if your current drive belt is loose or not, start your engine and push your throttle lever to the highest. Next, engage the cutting blades by pushing the lever upwards. If you hear the blades’ cutting sound right after you push the engagement lever, it indicates that the drive belt has the requisite tension in it and doesn’t need any adjustment.

If you notice that the blades aren’t cutting the grass after the very instant you push the lever and give a whirring sound, it means that your drive belt is slipping, thus pointing out the need for adjustment or replacement.

● Step 2: Inspect the mower deck components:

As we’ve seen, the drive belt is slipping; we need to troubleshoot this for the components located on the mower deck. To do this, lower the deck as much as you can and pull back your blade engagement lever. Then, you need to inspect the following components:

Belt: Make sure that your drive belt is intact and doesn’t appear damaged with chunks missing and cracks. If it seems damaged, then you should replace it right away.

Swingarm: The swingarm is a component on the deck where the springs are connected, and a pulley is mounted. The arm is pivoted at one end and free to rotate at the other end. Make sure that the arm is free to rotate. If it is not, drop some oil or a lubricant at the pivoted end, which might have been jammed.

After the above components are functioning correctly, push the lever again to engage the blades.

Spring: The cable that comes from the lever is connected to a spring. Touch the spring to see if it’s completely stretched or loose. Also, touch your belt at the same time and notice if it appears loose. If it does, we shall move on to the next step, adjusting the belt tension.

● Step 3: Tighten the belt by adjusting the cable:

After you’ve seen your belt loosened up, disengage the blade lever again. You would have noticed the wire that comes from the blade lever and is attached to the springs. On the deck, it is mounted on a bracket.

Loosen the bolts on the bracket is push it back in the direction away from the spring. You now feel that the spring is tightened up.

● Step 4: Test the belt for tension:

After the bracket has been pulled back, start your lawnmower engine at full throttle. Now, push the blade engagement lever upwards and immediately notice the cutting action of the blades. If the blades begin cutting without delay, it means that the belt tension is now optimal. However, If the belt still seems loose enough, it indicates that this method didn’t add the required tension, and therefore you should think about replacing the belt.

Related Questions:

1. How to remove and replace the drive belt on a riding lawnmower?

In most cases, tightening the drive belt does not solve the problem, and you often need to replace it altogether with an identical one. The steps for doing that are listed below:

Step 1: Disconnect the spark plug

First, you should turn off the ignition switch and remove the key. Next, you need to pull the mower hood upwards and disconnect the spark plug wire.

Step 2: Disassemble the mower deck

Next, you need to disconnect the entire mower deck from the main body of the lawnmower.

– Step 2.1: Lower the mower deck

As a first step, lower the mower deck on the ground to the lowest position and disengage the blades.

– Step 2.2: Roll the belt off

Roll the belt off the engine pulley and release the belt keepers.

– Step 2.3: Detach the deck

Now, you need to remove all the linkages that connect the mower deck to the upper portion from both sides of the mower deck. To do this, remove the retaining pins and washer supports from the lift link, suspension arm, and rear end bracket on both the left and sides of the mower deck. The deck should now be detached completely.

Step 3: Pull out the old belt

– Step 3.1: Take a picture

Note the routing of the blade belt on the mower deck. We recommend taking a picture to record the layout.

– Step 3.2: Remove the old belt

You might see three pulleys on the deck, namely one idler pulley along with belt keepers and two mandrel pulleys. Remove the old drive belt from the three pulleys.

Step 4: Install the new belt

Loop the new drive belt around the mandrel pulleys and pass it around the idler pulley through the belt keeper. Push the deck back under the mower.

Step 5: Reconnect the mower deck

Reconnect all the removed links such as the lift links, suspension arms, and rear end bracket back onto the mower deck through the retaining pins and washers. Attach the belt back to the engine pulley.

With the mower deck assembled, reconnect the spark plug wire and insert the key in the switch. Start your mower and test the new belt for performance.

2. How long is the drive belt on a Craftsman riding lawnmower?

Drive belts are responsible for transferring power from the engine pulley to movable parts in the mower, such as the blades. Craftsman lawnmower models consist of primary and secondary drive belts. Both belts have a length ranging from 42-55 inches depending on the particular model.

3. Why does the belt keep slipping off the lawnmower?

The drive belt of your lawnmower may come off for various reasons. The exact reasons may depend on the design of your machine. However, some general reasons resulting in this problem are listed below:

– Damaged parts:

The drive belts and idler pulleys may affect the belt operation if they are not in working condition. Moreover, the swing arm should be able to rotate freely about its pivot. You need to check the mower deck’s adjustment as well. For normal conditions, the deck’s front is generally lower 1/8 to 1/4 inches than the back. A pitch greater than this may cause the belt to keep slipping off.

– Debris Buildup:

The buildup of dirt and dust between the pulley and bracket may also reduce the friction attaching the belt onto the pulley. Make sure that no soil, grass, or sticks are found along the drive belt. This condition is quite imminent under rough operating conditions and low maintenance.

4. What are the two significant forms of drive belts used?

Transmission belts in machine design may be of the V-type or synchronous design. V-belts have a wedge-shaped cross-section. Friction is the only force keeping the belt attached. On the other hand, synchronous belts have a notched profile along their inner circumference, much like gears. They are generally mounted on gears and pinions and are used in timing operations.

Craftsman lawn tractor drive belt problems

If you want to replace the drive belt in your Craftsman lawn tractor, but do not know how to, use the following tips:

  • Make a short video or take some pictures before removing the old belt.
  • Ensure that you use the correct belt. You can use the model number that is often under the seat for this.
  • Check the idler tensioner springs and brake arms, and replace them when needed.

If the belt was damaged and it is gone, you can not find any information on how the belt should be routed. Use the following to understand where the belt needs to go:

  • Most Craftsman lawn tractors have up to 5 pulleys for the drive belt. They are easy to recognize.
  • The pulley underneath the engine is the drive pulley.
  • The pulley above the blades is easy to find. There can be 1 or two.
  • Generally, there is one spring-loaded pulley, that keeps the belt under tension. In some models, there is no spring-loaded pulley, but they can be moved to tension the belt.
  • The remaining pulleys are fixed pullies that take care that the belt is running around other objects.

Craftsman Belt Keeps Coming Off or Breaking

Generally, a craftsman belt can keep coming off due to several reasons:

  • Check for debris: Check the underside of the lawnmower for any debris that may lead to the belt coming off.
  • Damaged or stretched belt: When the belt is damaged or stretched it will become loose. A little bit of extra tension will be compensated by the tensioner, but if it loosens too much it will quickly come off. If the belt is damaged or stretched, it needs to be replaced. If you notice that the belt is slippery, maybe due to oil, clean it.
  • Damaged pulley bearings: If the bearings from one or more pulleys or from the spindle housing get damaged, it can result in too much slack for the belt. Check the different pulleys for movement, and replace the pulleys.
  • Belt keeper: If your Craftsman lawnmower uses a belt keeper next to the pulley, it may be bent or damaged. In that case, it may be the reason why the belt keeps coming off.
  • Dirty pulleys: The different pulleys have a groove that keeps the belt in the correct location. If those grooves contain dirt, it can lead to the belt coming off. Check and clean the pulleys.
  • Tension spring: The belt is kept at the correct tension with the tension spring. If the spring gets worn out, it may not do its job correctly. Check the tension bracket and spring. If the spring and bracket look ok, check if they can move freely. If not, grease all the moving parts. Replace the spring and bracket if damaged or the spring is worn out too much.
  • Wrong belt: Ensure that you use the correct belt for your Craftsman Lawnmower. The wrong belt, even if it may look fine, can result in coming off easily.

Final Comments:

Lawnmower belt maintenance may be one of the most frequently occurring instances, mainly if the mower hasn’t been well maintained in the past. We recommend cleaning your lawnmower occasionally and adequately checking the mower deck working components to see if they are in proper working order. Furthermore, you should always consult the owner’s manual when making a belt replacement. It is better to exercise caution while making these replacements to don’t end up accidentally starting your lawnmower.