Lawnmowers usually experience frequent use during mowing seasons that can cause some of their parts to grow weak. Not all the components of the mower are built to last as long as the machine.
You may have to replace a few parts as you use them. The belts, for instance, can grow weak or broken from frequent use. You need to measure the lawnmower belt accurately for a successful replacement.
Read this to learn how to measure a lawnmower belt
Most lawn mowers, especially riding ones, come with two belts. One of the belts links the lawn tractor’s transmission to the drive shaft pulley. The other belt connects the lawnmower deck to the drive shaft pulley. This one is called the deck belt.
The length of these belts depends on the brand and model of the mower. These belts can become loose or break with overuse. When it starts to get weak, you might want to measure them so you can buy new ones.
We’ll explain how to do that in two simple ways.
How to measure a broken lawnmower belt for immediate replacement
- Cut the belt – If the belt is already broken, you would not need to cut it. But if it is slack, and has not yet broken, cut through the belt with a knife.
- Place the belt on a flat surface – Place the belt on a smooth floor, long bench, or any flat surface. Keep it from rolling up by putting heavy objects on both ends.
- Measure the belt with tape – Put your measuring at one end and roll it to the other end to ascertain the length of the belt.
How to measure a lawnmower belt for replacement in the future
- Put the belt on a table or flat surface – Allow the belt to sit on its flat side so that it rolls into a circle when you let go.
- Mark the edge of the belt – On the inside edge of the belt, use chalk or bright colored marker to put a mark. Let the mark be on the belt’s V-groove’s tip.
- Measure the belt – Put one end of your measuring tape at the tip of the mark. Then extend the measuring tape around the circle till the other end reaches the mark you made. The reading on the tape is the length of your belt.
In case the belt is missing
As we have mentioned, the mower deck belt connects the deck to the drive shaft pulley. It’s the rubber belt on the inside and aids movement of the parts in the mower.
If this belt is missing, you need to replace it. But you need to first ascertain the size. We will explain how.
Note that some repair shops can help measure the belt for free. So you can simply take the belt with you to the shop or a store that supplies the equipment. They can help measure the lawnmower belt for free.
But if the belt is missing, you will have to determine its size before you buy a new one.
How to determine the size of a missing mower deck belt
To measure a missing deck belt, you’ll need to measure the distance of the circular parts attached to the deck that the belt wraps around. The circular parts are called spindle pulleys.
Follow these steps to do it:
- Remove the deck – Use a screwdriver or wrench to uncouple the lawnmower deck from underneath the machine. After this, you should be able to see the spindle pulleys and the deck belt.
- Locate all the pulleys – You should find between four to six pulleys on the deck, depending on the size. Observe the circumference of the spindle pulleys and assign a number to each of them. Note that the belt must be large enough to circle each of the spindle pulleys at once.
- Measure each distance of the circular parts (spindle pulleys) – Use a measuring tape to determine the distance of one spindle pulley to the next, and note down each measurement on a piece of paper or jotter. That is, the distance between the spindle pulley from 1 to 2, 2 to 3, and so on, till you measure all of them.
To determine the size of the belt, add all the measurements you’ve taken. The sum is the total distance around the spindle pulleys and the size of the deck belt.
The belts are important parts of the equipment. It connects the engine to parts of the machine that causes it to move. Therefore without it, your lawnmower would standstill.
Unfortunately, they are not as durable as the equipment itself and require replacement from time to time. The more you use the mower, the less the belts last. So there is no set time to change them.
However, there are signs to look out for which tell you that the belt has weakened and needs to be replaced.
Steps to fix the new drive belt on your lawnmower
Once you are sure you have the right size of lawnmower drive belt, you can fix it to the mower without professional assistance. The process should take less than an hour.
Follow the steps below to replace the belt:
- Clean the drive belt area – You might need to wear gloves to protect your hands from the blade. Or try to avoid the blade while you remove the dirt from the mower. Make sure you refer to the user manual to see the cleaning instructions.
- Uncover the deck – How to do this would depend on the type of mower you use. You might have to take out the spark plug to unscrew the mower deck cover. The procedure would be described in the user manual.
- Take out the guard on the belt around the engine pulley – On the crank shaft close to the engine pulley, there’s a guard holding the belt in place. Take this out gently.
- Take out the belt from the engine and transmission pulley by removing the bolt – Take note of how the belt is positioned, so you can fix it back correctly.
- Replace the drive belt – Fix the new belt around the engine and the transmission shaft. Return the spark plug and cover the deck
5 Signs of a failing belt on a lawnmower
- Decrease power on the mower – When the belt is worn, the mower might stop working well as power will decrease when you try to use it. This might go on briefly before the equipment breaks down completely. But when you notice a drop in its operation, check the belt for visible signs of damage or wear.
- Visible damage – A loose belt, cracking, or sidewall damage are all signs to check for while you use your mower. These visible signs may indicate the time for a replacement. These can cause the equipment to break down at any point.
- The mower vibrates when you turn it on – These might be signs of other problems, such as specks of dirt stuck somewhere in the equipment, a weak pulley, a blade that’s not balanced, or a failing belt. The bad belt might move roughly around the circular parts when the equipment is on, causing it to vibrate.
- Loud screeching noise – If the belt is worn, especially around the edges, it might cause the machine to make a loud screeching sound while you use it. Once you notice this sound, try to fix the issue immediately. If left unchecked, it can lead to damage to other parts of the machine and more problems.
- The belt falls out of the mower – If the drive belts keep coming out of the mower, the belt might be damaged. It might be loose, which can cause it to slip out of the pulley while in use. This is dangerous and could lead to a fire in the engine, due to the friction that results from parts touching. Although this sign might be a symptom of another problem, you need to fix it immediately and change the belt if necessary.
How to check the lawnmower belt
When you notice any of the above signs, you should first check the belt to see the exact fault.
Here are a few steps to check your mower belt:
- Turn off the mower
- Remove the blades with a wrench
- Inspect the belt. Check for cracks or bulges.
- If you see any crack, allow the belt to cool, then tighten it.
- If there are bulges on the belt, it might be too tight.
- Allow the belt to cool, then loosen the screws a little.
- If you are not able to loosen any screw or tighten the bolt, your belt might need replacement.
If you encounter any of the signs above, it is time to measure your belt for replacements.
Most belts come with the size on them. But these sizes may not be exact and can be confusing. Oversize or undersized belts can cause problems with the equipment.
It’s necessary to measure both the width and the length of your mower belt before you hit the shop.