Learn How To Open A Master Lock 4 Digit Combination Lock (Even Without The Code!)

Key Takeaway

  • To open a combination lock with 4 numbers, align the wheels on the lock face as per the digits of the code.
  • You can use a shim created using an aluminum can to open a 4-digit combination lock without code.
  • You may also try to crack the code of the lock by turning the wheels while creating tension on the lock shackles. 

It was some time ago that the old traditional padlocks were upgraded to number combination locks that work on the principles of physics. The number combination locks work on the basics of force and balance and unlock with the help of combinations and sequences. Contrary to padlocks that require a key to unlock, a combination lock requires a unique code to activate the lock.

Combination locks work great as chest locks, travel luggage locks, gym locks, etc. However, with the hustle and bustle of daily life, it is common for users to occasionally forget the code that opens the combination code, especially if it has not been used for a long time. As a result, you have to look for ways to open a combination lock without the code.

In this article, I will talk in detail about 4-digit combination locks. We will learn how they work and go through stepwise instructions on how to open a combination lock with 4 numbers, even without a code.

How Does A Combination Lock Work?

How Does A Combination Lock Work?

The principle of working a combination lock is similar to the working of a lever tumbler lock, which uses a set of levers that prevent the bolt from moving. The only difference lies in the fact that a lever tumbler lock uses a key to align the tumblers, but a combination lock uses a set of numbers to do the same. 

The lever, in the form of a hook, controls the shackle and also houses the latch and spring. Until the correct code is entered in the combination lock, the lever does not release the shackle. 

The lever is connected to the shaft, which further connects to the combination wheels. The number of digits in the lock’s combination code depends upon the number of wheels. For example, a 4-digit combination lock will have 4 wheels. Adjusting the wheels to a proper sequence allows them to align and provides room for the lever to move and let the shackle release.

How To Open a Master Lock 4 Digit Combination Lock

Master lock 4 digit combination lock cracked open

If you know the code or have the code of the lock written somewhere, opening a combination lock is an easy task. 

Here’s how you can do so.

  • Step 1: To unlock your combination lock, set the first wheel at the right number. The first wheel would be either the leftmost or the topmost wheel on your lock, depending on how the wheels are placed. Move the wheel clockwise or anti-clockwise to ensure that the correct number is right in the middle.
  • Step 2: Once the first digit has been lined, adjust the wheel next to it. Ensure that the digit lines with the correct digit on the first wheel.
  • Step 3: Repeat the process with the third and fourth wheels and correctly set all four correct digits of the combination code.
  • Step 4: Once you are sure that the wheels have been set at the correct combination code, pull the shackles of the lock to unlock it. If, in case, you fail to unlock the lock, recheck the combination code and repeat the process. 

The above process will help you unlock your combination lock using the 4-digit combination code. In case you do not remember your combination code, check whether your lock is resettable. If so, check the serial number on the lock and contact your lock manufacturer to reset the code. However, to be able to succeed, you will also have to provide them with a Notary Public stating that you are the legal owner of the lock.

How To Unlock A 4-Digit Combination Lock Without The Code

If your lock is not resettable, you cannot access the lock serial number, or you need to access the lock in an emergency, you can use alternative ways to unlock your combination lock. 

If you are looking for how to crack a 4-digit combination lock, this section of the article will help you learn two methods for the same. 

Cracking The Code By Creating Tension On the Shackle

In this method, the idea is to crack the code of the combination lock by creating tension in the lock shackle. The tension in the shackle helps find the position of the lock where the wheels are aligned. 

Brinks 4 dial combination cracked open

Let’s learn how

  • Step 1: Take a piece of rope and run it through the lock shackle. Pull the rope to create tension in the shackle. This will, in turn, create friction among the lock wheels so that when the wheels are moved, it is possible to hear a click sound to understand the correct position of the wheel and, hence, crack the code. You could also use other means to create the tension. I did it with my fingers.
Creating tension on master lock 4 digit combination lock
  • Step 2: With the rope pulled up, try turning all the wheels on the lock to determine the wheel that is the hardest to move because that is where you have to begin with cracking the code.
  • Step 3: Once you have found out the hardest-to-move dial, rotate it with the shackle pulled up until you hear a ‘click’ sound and feel the shackle move up slightly. Repeat the process a couple of times until you are sure that the wheel clicks on the same number each time. Note down the number, as that is most probably the digit for that wheel.
  • Step 4: Keep the first wheel positioned at the digit discovered and look for the second digit. Again, bull the shackle of the lock and identify the wheel that is hardest to move. Next, rotate the wheel with the shackle pulled up until you hear a ‘click’ sound and feel the shackle move up slightly.
  • Step 5: Repeat the step to find the combination code’s third and fourth digits. In each case, you need to rotate the wheel until you hear a clicking sound while the shackle is pulled up.
  • Step 6: Once you have figured out the combination code, pull the shackles of the lock to unlock it.
Cracked the code on Master Lock 4 digit combination lock

Using a Shim To Open A Combination Lock

Using a Shim To Open A Combination Lock

This method to open a combination lock without the code may not work on all locks. But if your lock is not shim-proof, you may try your luck with the method.

You can create a shim to unlock the lock using an aluminum can. Here’s how

unlock the lock using an aluminum
  • Use scissors to cut off the top and bottom of the can. Cut the remaining cylinder to length to get a rectangular aluminum sheet.
  • Cut a 1-inch wide strip out of the aluminum piece. Ensure there are no ragged ends on the strip.
  • Place the strip horizontally and cut out two curves to make two U-shaped incisions. The end result would like a curved M, as shown in the figure above.
  • Fold the sides to create a shim with a tongue piece out. Ensure there are no ragged ends on the shim to avoid cuts on your hand during the process.

Once the shim is created, follow the steps given below to open the lock.

  • Step 1: To begin working with the shim, first identify the side where the shackles lock as that is where you would begin, not the hinge. Most locks have the locking mechanism on the left side of the lock when the face of the lock is towards you. 
  • Step 2: Next, fold the shim around the shackle with the tongue (U) of the lock facing downwards. Once you have wrapped the handle, turn the shim in a way that the U is placed on the inner side of the shackle.
  • Step 3: Pull the shackle up as strong enough that the dials should offer resistance to moving. Simultaneously, using the other hand, slowly push down the U into the lock where the shackle meets the lock. Do not rush through the process. 
    Pull the shackle up
  • Step 4: When you feel the shim has reached as far as it can, stop and release the shackle. The lock should pop open. If it doesn’t open, push the shackle down are then pull it open. 

Frequently Asked Questions

Q1. Is there a way to retrieve the combination code of a lock in case I have forgotten it?

Answer – If you can’t recall your combination code, see if your lock can be reset. If so, check the lock’s serial number and get in touch with your lock manufacturer to reset the code. However, in order to succeed, you must also supply them with a Notary Public certificate declaring that you are the legal owner of the lock.

Q2.How can I break open a combination lock?

Answer – Smaller locks with thinner shackles can be hacked with a hacksaw, while heavy-duty combination locks require an angle grinder to cut the shackles. The trick is to cut through the shackle perpendicularly and patiently until you succeed. Keep your hands away from the lock and grip the padlock using pliers. 

You may also drill through the lock with proper precautions to break it open.

Q1. How to open a combination lock using a pair of wrenches?

Answer – Yes, you can open a combination locking using a pair of wrenches, but this will break the lock shackles, and the lock would not remain functional for future use. 

Using the mouth of the wrench, secure both sides of the shackles. Bring the handles of the wrenches as near to one another as you can after firmly grasping the shackles. Apply simultaneous pressure to both wrench handles to break the shackles. Make sure you have a good grip on the wrenches so that the head securely clasps the shackles when the force is applied. The strength of the shackles determines how much power is necessary to break them.


Combination locks can get a little tricky to open without the combination code. But like most other locks, there are workarounds that can help you open a combination lock without a code. If you were looking for how to open a combination lock with 4 numbers, the article must have helped you. You may either try cracking the lock’s code or pry it open using a makeshift shim. 

And if you succeed, don’t forget to write to us! You are welcome to share your views and experiences with us as you progress through the steps. You may also forward this post to friends who have difficulty opening their combination locks.

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Hey! I am Mark. Though I am not a locksmith by profession, but locks have always fascinated me since my teens. And it all started when I got locked out of my house and I had to pick the lock. Since then it has become my hobby to learn more about different kinds of locks, understand their working and methods to pick them up. In due course of time, I have also become better aware of how installing the right lock goes a long way in ensuring iron clad security. I aim to share my passion (about locks) through this blog. If you are also passionate about picking locks or are just looking to beef up the security, hop on the ride.