How to tighten the drive belt on a craftsman lawnmower, step by step


Craftsman lawn mowers are among the better and faster machines you can purchase. They are efficient and do their job pretty well. The mower owes much of its skills to the blade engagement system. That is controlled by a drive belt system, running over a set of three pulleys. To keep your mower working effectively, you have to look after these individual parts. In your routine maintenance, you have to check that the drive belt is functioning correctly. With time, the belt gets stretched due to its fast speeds. This may cause the belt to sag between the pulleys causing issues like engagement delay, power disruption, and jerks. If you face such problems, you have to adjust the tension to the drive belt. You have to tighten all connections so that the belt is tight over the pulleys. This article will give you step-by-step instructions to tighten the drive belt on a craftsman lawnmower.

How to tighten the belt on a craftsman lawnmower, step by step:

  • Step 1: Gather the necessary tools and remove the spark plug
  • Step 2. Position your lawnmower on a leveled surface
  • Step 3: Remove the mower deck
  • Step 4: Tighten the belt bracket
  • Step 5: Tighten all pulley connections
  • Step 6: Double-check the blades
How to tighten the drive belt on a craftsman lawnmower, step by step 1
(CC BY 2.0) by ToddMcCann

The drive belt is responsible for carrying the engine’s power to the blades. It connects the two systems ensuring a continuous motion without any jerks. With time, the rubber of the belt expands over repeated cycles due to fatigue and heat. This causes the blade to move loosely, which is an issue for a lawnmower’s performance. Much similar to adding a new belt, tightening the belt requires some of the same steps. For most craftsman lawnmowers, you will have to remove the mower deck, its connections, and some other components. While you are tightening it, you can also check the belt and the condition from some other components.

General Guide:

Use the following steps to tighten the drive belt on your craftsman lawnmower. If you think this job is beyond your skill level, ask a professional for help.

● Step 1. Gather the necessary tools.

Using the right tools and guidance in any scenario makes the job much easier. The same is the case with tightening the drive belt. For the job you need the following tools:

  • A pair of safety gloves.
  • Set of Pliers.
  • Screwdrivers.
  • Adjustable wrench.
  • Woodblocks.

● Step 2. Position your lawnmower on a smooth surface.

Park the craftsman mower on a smooth and level surface before you start to work on it. Put the mower in gear so that can not move forward. Apply the mower’s parking brakes for the same reason. Disconnect the spark plug cables. This is a precautionary step to prevent the mower from accidentally starting up when you are working on it.

Set the mower deck to its lowest possible setting. In some craftsman models, you can directly access the belt from beneath without removing the mower deck. For some other models, this is not, or extremely difficult. For those, you need to remove the cutting deck. This makes your approach to the pulleys much easier, which are attached to the deck.

If you have a lawnmower lift you should use it. This makes it easier to access its base connections.

● Step 3: Remove the mower deck

If you need to remove the craftsman mower deck, move the deck height adjuster to lower the deck to the lowest possible point. A bolt is present on the deck’s rear section near the tire, and bow clips are present above this bolt. Remove these bow clips. After that, disengage the cutting blades. You can do this by pulling the log lever towards you, which is present on the side of the steering wheel. Now, release the drive belt from belt keepers by rolling the blade belt off the engine. Detaching the support from the deck is very necessary from both sides. In this case, you need to remove the pin and washer support for the drag links and suspension arms on both sides. Remove the left suspension arm retaining clip, washer and detach it.

Now, release the bracket from the deck by removing the left rear deck bracket clip. Similarly, the right suspension arm and right rear bracket can be removed by repeating the same process. After removing right and left suspensions, arms, and rear brackets, pull the deck out and access the blade cable attached to the deck.

● Step 4: Tighten the belt bracket

Before starting with the tightening, you need to check the current drive belt condition. You must have your mower on a raised platform to make the task easy. Look at your belt and make sure that there are no cracks. If you see some cracks and chunks at this time, replace the belt. Next, inspect that the spring arm is working correctly. Ensure that it moves back and forth correctly. Beneath the deck, check by hand that the spring attached to that spring arm is a bit slack, and the belt is easily stretched by hand. Also, check the slackness of the belt as it passes over pulleys. If it is sagging below, it needs tightening.

Now you can start with the adjustment. The drive cable comes from the craftsman drive control panel down to the transmission panel. At the point where the cable attaches to the pulleys, there’s a small bracket. This same bracket is used to adjust the tension in the drive belt. As the deck and blades are cut off, everything beneath the deck is in a slack position. Now, using an adjustable wrench, loosen the bolt fastening the bracket. Pull it away from its position so that it stretches the cable attachment. At this position, tighten the nut. Now, check the belt by feeling its tension and stretch over the pulleys.

● Step 5: Tighten all pulley connections

This step is additional if adjusting the bracket doesn’t solve your problem. Now that you have opened the mower deck, you need to check the idler and mandrel pulleys over the deck. Check if they move freely and tighten their screws if they wobble. Repeat the same with the driver pulley present beneath the engine’s crankshaft. Now that the pulleys are adjusted, check various connections over which the belt moves. Lubricate the pulleys and the belt. Check the connections of spring arms and tighten all bolts with washers and seals. Now, adjust the craftsman mower deck back in place. Reconnect the suspension arms and similarly the drag links.

When you are done adjusting the blade belt, push the log lever away from the steering wheel to engage the mower deck and blades. Check that the spring is fully stretched. From beneath, check the sag in the drive belt.

● Step 6: Double-check the Blades.

Check if the belt and pulley system is working correctly. Use a pair of heavy safety gloves, twist the mower blades and check if the belt moves over pulleys without lagging or sagging. Reconnect the spark plug, and start the mower engine. Now you can see if the belt and pulleys are driven correctly. If they are, your blades should be continually moving and instantly start rotating as you engage them.

Some precautionary measures

Following are some preventive measures that should use while performing the above task:

  • Use hand gloves: For some of the tasks, it is good to wear sturdy hand gloves to protect your hands.
  • Remove the spark plug cable: Ensure to unplug the spark plug cable. You do not want to have the mower starting unintentionally when working on the belt and near the blade.

Frequently asked questions:

1. What are the reasons that cause the mower belt to break?

The mower belt may break if it is older and has seen some wear and tear. Dry and thick grass requires more power, hence increasing the load on blades and belts. This and other events suddenly put more strain on the belt and causing it to break suddenly.

2. How do I know which belt I need?

The craftsman lawnmower always comes with a certified and detailed user manual. It has all of the engine specifications and parameters. In the transmission section, you can find information about your blade engagement system. There, the exact belt requirement and brand will also be mentioned. Always make sure you use a belt that has the correct length and shape.

3. Why do I need to tighten my lawnmower mower belt?

The power transfer from the engine to the blades is through the belt, so your belt must be suitably tight. If it is loose, the lawnmowers face lagging issues; there is a time difference between engaging the blades and their actual engagement. The mower may jerk while cutting grass. A loose belt may eventually affect the other components like pulleys.

Final remarks:

A craftsman riding lawnmower is known for its fast and robust performance. This feature owes much to the drive belt mechanism controlled by the three pulleys on the mower. With time, the belt gets loose due to high-speed operation. Hence, tightening the belt is essential, and every passionate gardener should know about it. This article has provided you with a simple, efficient way to tighten the mower belt while checking the related components for error. If you follow all the steps in order, your issue will be fixed.

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