How Does A Lunchbox Locker Work? Pros And Cons

So you have heard the term ‘lunchbox locker.’ But don’t know what it is. Well, no worries, because in this article I will discuss everything you want to know about lunchbox lockers.

In the world of off-roading, you need plenty of modifications to improve the performance of your vehicle. Out of all improvements, modifying the set of lockers is perhaps the most important one. This is because it helps in improving the power of your 4-wheeler. Besides that, it also proves beneficial in enhancing the vehicle’s traction.

Before you set out to buy a new set of lunchbox locker, you need to know a few important things about it. In this post, I am going to cover everything related to lunchbox lockers. I will also answer common questions like “Is a lunchbox locker always locked?” and more. That said; now let’s walk you through the post.

What Is A Lunchbox Locker?

Before moving onto any further details, let us first learn what a lunchbox locker is.

To define it in simple terms, it is a locker mechanism designed to fit into the stock differential carrier. It is used in the place of a spider gear set and sometimes the pinion-shaft and side gears. It is also known as a drop-in locker.

There are different kinds of lockers available out there and each one of them works differently. They also have their fair share of pros and cons.

Lunchbox lockers make the perfect option, especially when you are on a budget. The nickname lunchbox is derived from the idea that you pack different lunches in the same lunch box. In this case, the locker is the lunch and the stock carrier in the box.

How Does A Lunchbox Locker Work?

Now coming to the most important question how does a lunchbox locker work.

A lunchbox locker features a design that splits power evenly between two wheels regardless of wheel traction. But it has to stay open in normal driving situations for the differential to work properly. You can say that this is a huge improvement over the basic open differential which transmits all the power to the wheel with very little traction.

The hole of a lunchbox locker where the center pin goes through features an oval shape, instead of a circle. The application of torque forces the pin to move a little bit. The pin then pushes the cam gears into the axle gears and thus locking them together.

When there’s no torque applied the pin stops pushing the cam gears outwards and returns to the center of the oval. This allows the cam gears to spin past the axle gear which creates the ratcheting noise that lockers are popular for.

Many of you wanted to know “Do lunchbox lockers work in reverse?” Well, the only time lockers are unlocked is in a turn. Unless they are the manual disengage type, reverse or forward doesn’t make any difference. The auto lockers are unlocked when there is no torque applied. They can be locked again, but that depends on the skinny pedal.

What Are The Different Types Of Lockers?

As already mentioned, there are different types of lockers available out there. In this section, I will discuss the most popular lockers. Here is a brief rundown of the different locker types:

Selectable Locker

This is an on-demand unit that is activated electronically. Alternatively, it can also be activated pneumatically via a cockpit-mounted button. One good example of a selectable locker is the Yukon Zip Locker.

Mechanical Locker

This type of locker is always active and thus, providing traction 24/7. The Yukon Grizzly Locker and Spartan Locker are good examples of mechanical lockers.

Mechanical lockers are also called automatic lockers. During off-throttle situations, when the diff is unloaded, it loads to a partially unlocked unit. When the vehicle and the two wheels turn on the axle at different speeds, it produces a clicking sound. This is called the ratcheting sound which can be loud. It is because of this reason that mechanical lockers are not considered to be the best fit for vehicles that are mostly out on the road.

Selectable Locking or Limited Slip Differentials

There are more than one ways from which you can get benefitted from the locking differentials on your truck.

Limited Slip Differentials

This is the combination between an automated locked differential and an open one. The good thing is they are automatically controlled by the vehicle. Also, they are locked and unlocked as needed.

Selectable Differentials

This includes fully-locking differentials that are required to be activated and deactivated manually as needed.

Compared to a completely open differential, a limited-slip differential is much better for off-road conditions. That’s because you can still have control over it while going for general off-roading.

Some vehicles come with built-in limited-slip differentials. But including a set of lockers to your rear and front differentials will give you the highest degree of control. It will help make your wheels powerful and also increase the amount of traction.

How To Install A Lunchbox Locker?

Installing a lunchbox locker may seem to be intimidating for the first time. But once you successfully install it, you will get an idea of how it is done.

To begin with, the lunchbox locker replaces the spider gears inside the stock carrier. This means you don’t have to reset your backlash while installing a lunchbox locker.

You can install lunchbox lockers without removing the differential from the axle casing. This is easier than lockers that are required to be fully disassembled.

Installation Tips and Tricks

If you are installing a lunchbox locker for the first time, you may need some extra help. Here are some useful and tips and tricks for you:

If you can remove the spider gears without moving the carrier from the housing, you can then complete the installation without removing the carrier from the diff. However, if it feels too tight, you will have to remove it.

In case, you have been using Spartan Lockers, they come with a very detailed installation manual including an array of images and step-by-step instructions. The guide addresses installation in a wide range of differentials. The bottom line is that Spartan Locker’s drivers are assembled with the alignment springs and pins installed.

The installation wires help keep the unit together until the installation is over. After that, they are removed by releasing the spring tension that helps operate the unit properly.

Should You Go For Lunchbox Lockers?

Now the question is whether lunchbox lockers are for you. To answer this you need to first understand a few things.

The most important point is vehicle usage. I am not only talking about how much your vehicle will be on the street, but also about off-road usage. How much you want from your driveline comes into play.

Let’s say if you are staying on the trail with moderate scrambling over rocks, hill climbing, and the like, going for a lunchbox is a good decision. However, if you want to get more aggressive and drive in some extreme situations, then you should go for a large-frame locker.

As far as the clunking and ratcheting sounds of the unit is concerned, read up on the subject. Some users say that the noise fades with use, while others say that it is intrusive.

Pros And Cons Of Lunchbox Lockers

Using lunchbox lockers has both advantages and disadvantages. You must weigh the pros and cons before getting lockers.

The main advantage of lockers is the fact that they are simple devices that are designed to fit into a stock open carrier. Since the ring gear is connected to the carrier, you don’t have to set up the ring and pinion gears again. This makes it easier for a mechanic to install a lunchbox locker.

Lunchbox lockers with a very simple design are not as good as you think. Most of them have some kind of issue. One of the main problems with lunchbox lockers is that they make very loud ratcheting sounds when turning. They can also unexpectedly get locked and unlocked at times. This largely depends on how you corner in vehicles.

If you maintain the same speed or decelerate in a corner the locker behaves just fine. But as soon as you accelerate the locker, it can pop into its locked position. Due to the violent locking and unlocking mechanic, lockers are short-lived.

Lunchbox lockers feature a very simple design. It is because of this reason that the cost of lockers is low. They are very easy to install. Lockers make a great option, especially when you are on a budget. If you are planning to buy a lunchbox locker, I would recommend you to buy one for the front axle. This will help get rid of the on-road handling issues.

This is possible because your vehicle will be in 2WD on the road and the locker won’t lock or unlock on its own. Hopefully, you found this article helpful and found the details you have been looking for.

Thanks for reading and stay dirty