Lock Picking Tension Wrenches: Know it All Guide

If you are a beginner in locksport, would you believe if I tell you that 90% of your time should go in using tensioning tools properly and only 10% should go to other lock picking tools?

Probably not! You would dismiss my advice and take me for a mad man. But trust me when I say that using a tensioning tool (or a tension wrench) is the most critical aspect of the lockpicking skill. I wish someone had told me this when I was just starting out.

In this tell all guide, I will explain almost everything about tension wrenches. I will cover what a tension wrench is, how it looks, what its purpose is and its different types. My aim from this article is to educate you about how to pick the right tension wrench for a lock and not do the mistakes that I committed.

What is a Tension Wrench?

A tension wrench (or any tensioning tool) provides rotational torque to the core (plug) that stops the pins from falling back due to springs thereby helping the picker to set the pins. It is undoubtedly the most important tool in your lockpicking kit.

I am sure you will agree with me when I say we, lockpickers, thrive on the feedback. It is the most important arrow in our armour to understand the lock internals. And a tension wrench provides us the purest form of feedback that any lockpicking tool ever can.

What Does a Tension Wrench Look Like?

The Straight Wrench
The straight wrench

Tension wrenches come in a variety of shapes and sizes; each for a specific purpose. I will cover different types of tension wrenches later in the article.

However, the above image shows a straight (or standard) tension wrench. It is an essential part of any lockpicking set. If you are just beginning your journey in locksport, you will most likely be using a straight tension wrench. 

How to Use a Tension Wrench? The Science Behind

In a pin tumbler lock, which is the most prevalent lock, the pins are spring loaded. When you insert a key, the key pins are lifted to the sheer line, thereby freeing the plug to rotate and hence opening the lock.

As a lock picker, when you try to set an individual pin to the sheer line, they will fall back to their position due to the force exerted by springs until and unless stopped by something. 

When you insert a tension wrench and rotate the core (only a bit), the pins don’t fall back as the rotated core stops them midway thereby helping you set them. 

Here is a video that I did recently on how to use a BOK(bottom of the keyway) tension wrench the correct way.

Different Types of Tension Wrenches for Lock Picking

Now that we’ve understood what a tension wrench is and how to use it, let’s move on to the different types of tension wrenches and when to use them.

Tension wrenches can be classified based on their shape, size and where they are used.

Most common types of tension wrenches based on shape are – 

  1. The Straight Wrench
  2. The Twisted Wrench
  3. The Double Ended Wrench
  4. The Serrated Wrench

The Straight Wrench

The Straight Wrench
The Straight Tension Wrench

A straight tension wrench is a flat metal (more often than not steel) piece with a 90 degree bent at one end. It is also called “L” tension wrench as it resembles the letter.

Remember I said above that tension wrenches provide the best feedback than any other lockpicking tool?

A straight wrench is the best tensioning tool to get the most unadulterated feedback from the lock. Since it is a long and thick piece of steel with no twist and turn, the slightest feedback from the lock (be it a click or pin being set) is transmitted to us without any adulteration. And this paves the way for us to know more about the lock internals.

Good For: 

A straight tension wrench is good for almost every kind of pin tumbler lock or wafer lock. Theoretically, you can use it as Top of the keyway (TOK) as well as bottom of the keyway (BOK); though it is easier and most commonly used as BOK.

The Twisted Wrench

The Twisted Wrench
The Twisted Wrench

A twisted wrench has a 90 degree twist down the shaft of the wrench and is used as TOK tensioners. They might look weird at first but are quite common in locksport.

There are a couple of things that you need to understand about a twisted wrench.

  • They are the worst tensioning tools to pick if you are just beginning your journey in locksport. The twist at the end of the shaft acts as a spring and dilutes the feedback coming from the lock. Needless to say, this is detrimental to our single pin picking skills.
  • They are slightly better than straight wrenches in terms of convenience of usage. Since there is a twist right at the end of the shaft, your fingers will rest on the flat side rather than the edge when applying the rotational pressure.

Note: I have not used twisted wrench too much myself as I value feedback more than the convenience.

Good For: 

Twisted wrenches are good for intermediate to advanced lockpickers who have already learnt the art of understanding even feeble feedback and value convenience more. 

The Double Ended Wrench

The Double Ended Wrench
Double Ended or “Z” Wrench

Double sided tension wrench is two straight wrenches rolled up in one. It is also known as “Z” tension wrench due to the resemblance with the letter.

Usually, both ends of “Z” wrenches are of the same width but different lengths. Different lengths prove to be helpful in picking different kinds of locks which I have covered later in this article.

Good For:

Double sided tension wrenches work the same way as straight wrenches. The benefit of using them is that you will have to carry less number of wrenches as two ends of the “Z” wrench have varying lengths.

The Serrated Wrench

The Serrated Wrench
The Serrated Wrench

Serrated wrenches are straight (“L” shape) or double sided (“Z” shape) tension wrenches with serrated teeth. Both Peterson and Sparrows sell these types of tension wrenches.

Serrated wrenches are used as TOK (top of the keyway) and are deployed when the keyway is really small. The serrations at the end locks the wrench and prevents it from falling down.

Serrated wrenches also come with a twist at the end of the shaft much like the twisted wrench. Twisted serrated wrenches provide the same convenience as twisted wrenches do.  

Good For:

Serrated wrenches are suitable for intermediate to advanced lockpickers who use TOK tensioning tools. They are particularly useful for locks with tiny keyways.

Top of the Keyway (TOK) or Prybars

Top of the Keyway (TOK) or Prybars
Top of the Keyway (TOK) or Prybar

All the tension wrenches mentioned above (with the exception of serrated wrenches) are used as BOK (bottom of the keyway) tensioning tools.

However there are tension wrenches that are meant to be used as TOK (top of the keyway). These are also known as Prybars.

Let’s now understand the importance of using a TOK tensioning tool.

When we are working with single pin picking (or raking for that matter), we want room in the keyway to work with our lock pick. We want enough space so that we can move our hook to lift the pins up.

This isn’t a problem when keyways are large since tension wrench and the hook can easily slide in the keyway. However, when keyways are small, this poses a challenge as the wrench eats up quite a bit of space leaving us with no room to manoeuvre the hook.

In such a case, it becomes easier to use a TOK tensioner as now the keyway is totally available to use our lockpick.

However, using a standard wrench as TOK isn’t easy as it will keep falling out of the keyway. Even if it holds its position, applying enough pressure will be a task. Hence, the need for a prybar or some sort of serration as in the case of serrated wrenches.

Tension Wrenches Width

Tensioning tools come in a variety of widths. Understanding how wide your tension wrench should be is very important since locks’ keyways are of varying width too.

If you use a wide wrench in a small keyway, you will end up wasting a lot of space that will not leave enough room for your lockpick. 

Most tension wrenches fall between .020″ and .030″ thick.

Further, they are classified under these categories – 

  • Thin: 0.1“ or 1.5mm
  • Medium: 0.11“ or 2.75mm
  • Thick: 0.13“ or 3.5mm

Most manufacturers will have their tensioning tools in these widths. And even if they don’t, they will have similar categorization.

Long vs Short Tension Wrench

Another aspect to consider before choosing a tension wrench is whether it is short or long relative to the lock. Let me explain this in a little more detail.

Whenever we are picking any lock, we don’t want the tensioner to go all the way to the end of the keyway. Wondering what’s the reason?

If the tension wrench will go till the end of the keyway, there will be no room left at the rear end to manoeuvre the lock pick. This is especially true where the last pins are cut very low. In such a scenario, you want every space possible to lift the pins up.

Ideally the tension wrench should go till midpoint of the keyway. So if you feel that the wrench is long for the lock, try changing the wrench to a shorter one.

Given this above knowledge, you might ask then – What’s the use of long tension wrenches at all?

Long tension wrenches come in handy for recessed keyways; a recessed keyway is one where the keyway face doesn’t sit flush with the lock body. 

Since keyways are recessed in these locks, we want a longer tension wrench to go to halfway point.

Master lock 911 is a prime example of the same. It has a keyway cover and working on it with a short wrench will prove to be ineffective.

How to Choose the Right Tension Wrench?

Choosing the right tension wrench for a lock depends on the following factors – 

  • Type of Lock: Before selecting a tensioning tool, it is important to understand what kind of a lock we are dealing with. Is it a pin tumbler lock or a wafer lock? If it is a standard pin tumbler or tubular lock? Because if it is a tubular lock, then we will need tubular tensioning tools that are not covered in this article.
  • Keyway Dimension: Next factor to consider is the keyway dimensions. Is it small or wide? Is it recessed or the keyway face sits flush with the lock body? If it is recessed, then we will need a long tension wrench.
  • TOK or BOK: Last consideration is whether you are a TOK person or a BOK dude? Prybars are best suited for TOK whereas standard wrench is the best for BOK style.

Recommended Tools for Different Scenarios

Find below recommended tension wrench for different types of locks.

ScenarioIdeal Option
Pin tumbler lock with keyway sitting flush with lock bodyStraight wrench for BOK stylePrybar for TOK style
Short tension wrench in either caseDo experiment with the width though depending on the keyway
Pin tumbler lock with recessed keywayLong straight tension wrench
Tubular lockCircular tensioners 

In my experience, most of your time will go in picking pin tumbler locks with the keyway sitting flush with the lock body. Therefore, you will be using a straight wrench or prybar depending on your individual style.

If you are a beginner in the locksport, I would recommend practicing with straight (“L”) tension wrenches. They should be good on every type of lock that you will pick. However, finding the correct width will come with practice only.

Move on to other tension wrenches only when you’ve experimented enough (successfully) with a straight wrench.

How Much Tension to Apply?

In this section, we will touch upon the most debated topic in tensioning – How much tension is good enough? 

Some say that you should apply light tension for the fear of damaging the pins. Others say that heavy tension is the best way as it provides the best feedback. 

I will not go into the theoretical aspect of this debate. Having said that, let me mention here that I prefer heavy tension for the following reasons – 

  • The feedback is better and much clearer. 
  • Heavy tension is also beneficial for those locks that have strong springs. 

Ultimately, the knowledge of how much tension is sufficient enough for a lock comes with practice. No article or guide can build that muscle memory. 

I recommend applying different levels of tension on a lock to see what suits your style better.

Frequently Asked Questions

Q1. Do you need a tension wrench to lockpick?

Answer – Yes, a tension wrench is mandatory for picking a pin tumbler lock, tubular or wafer lock as it prevents the pins from falling back (when set) due to the force exerted by springs. 

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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.