Does a Lawn Mower Blade Need a Torque Wrench? (Solved & Explained!)

While you can tighten and loosen without one, a torque wrench for your mower blade is a good idea. Over or under tightening the bolts can cause all kinds of issues with your mower blades and engine. Using a torque wrench helps to make sure that you use exactly the recommended pressure every time!

For the remainder of this article, we’ll take a look as recommended foot pounds of torque, why blades sometimes won’t engage, and more. Take a look at the most commonly asked questions and the important answers that you need below!

How many foot pounds does it take to tighten a lawn mower blade?

For tightening up a 9/16-inch socket (a standard with many mowers), then you are looking at a 30-foot pounds torque setting for getting the blade set-in nice and tight. If you are uncertain how to set your specific torque wrench for this, just check the documentation that came with it to ensure that you are setting it to the ideal 30-foot pound torque.

How do you tighten a lawn mower blade?

Most lawnmower blades are designed to turn clockwise, which will look like counter-clockwise when viewed from below. As such, you want to remove the spark plug and secure the blades from moving with a piece of wood and after that, you need to turn the nut towards the right in order to tighten it, or left for loosening the nut to remove it and replace the blade.

What tools do I need to change a lawn mower blade?

Ideally you should have a vise to hold the blade and an adjustable torque wrench to loosen the nut. If you don’t have a torque wrench then you can make sure with a large crescent wrench. The reason it should be large is so that you will get more leverage — those reverse threat nut and bolt assemblies can be quite tight and hard to move otherwise!

How do you tighten a lawn mower blade without a torque wrench?

Without a toque wrench, a crescent wrench can definitely do the job, but you want to use the biggest one that you can find and make sure that you have a lot of leverage.

Don’t forget to remove the spark plug first and to secure the blade from moving – a block of wood will do nicely. After this, you should be able to tighten the blade with no issues unless it has been rusted in place.

What causes a lawn mower blade to keep coming loose?

While the vibration from regular use contributes, most of that is going to be displaced by the use of reverse threading in the bolt. The most common reason that your blades end us loose is running over unexpected objects. Rocks, tree roots, and even too much wet grass mowing can take a toll on your blade and loosen the nut and bolt assembly.

You’ll notice this, generally, as more vibration after hitting the item but even if you don’t feel that, it’s best to stop the mower immediately and to tighten the mower blade… just in case! A loose blade can damage your mower and your lawn, so this is a useful habit to get into.

How much torque should a lawn mower blade have?

While a 30 foot pound torque is good for tightening, the ideal recommendation for installed blades is 38 to 50 pounds of torque for a standard push mower. Riding mowers have larger decks and rotate the blades much faster, so for these you should use 70 to 90 foot pounds of torque to ensure best performance and safety of use.

How tight do lawn mower blades need to be?

The ideal tightness for mowers is 70 to 90 pounds of foot torque, while push mowers should be at 38 to 50 foot pounds for torque. This will help to ensure even cuts but more importantly, it helps for when you accidentally run over something with the mower. A loose blade can do a lot of damage, so try to keep at close to these recommended levels as possible.

Why are my mower blades not engaging?

The most common cause for your blades not engaging is a loose, stretched, or slipped belt. During heavy use, grass and weed clippings can push up underneath and end up packing tightly into the deck, until eventually they move the belt. Clean the mower thoroughly and check the belt itself to see if it may be re-secured or if a replacement is required.

How often should you replace lawn mower blades?

On average, it is recommended that you replace your mower blades every 100 to 200 hours of work use. Exceptions are made, of course, for blades incorporating tungsten edges or specialized steel, and in some cases, these may last as much as 400 hours before needing replacement.

If you aren’t certain, be sure to check with your vendor for the recommended replacement frequency..

How do you remove a lawn mower blade without removing the deck?

With a push mower, it can be placed on its side, provided that you remove the spark wire and turn off the gas tap to prevent leaking of gasoline. After this, you can put a wood block in place to keep the blades from turning and sharpen with a whetstone, file, or an angle grinder.

With a riding mower, you can try elevating the deck by placing wood underneath the lip and then securing the blades in place with C-clamps. You won’t have a lot of space to work with, but this should allow you to access the blades for sharpening. As with the push mower, cut off the power by removing the spark line or plug.

Should I use Loctite on mower blades?

Loctites are quite useful and the Loctite 271s are great for standard mowers (just be sure to check compatibility with your exact make and model). By attaching them to your existing nut and bolt assembly, you can protect these from corrosion and they also provide additional protection against temperature, vibration, and other factors that can loosen their lock.