What types of wrenches are there: a complete guide to choosing for auto repair

A wrench is a tool that no car repair can be done without. From changing a tire to complex engine work, the right wrench is required. But how to understand their diversity? Horn, cap, end, adjustable - each type has its own characteristics and scope of application.

In this article we will analyze in detail all types of wrenches, their design, advantages and disadvantages. You will learn which tool is best suited for certain jobs, how to choose the right size and avoid mistakes when purchasing. And also - a table of correspondence between inch and metric sizes, tips on care and storage, as well as answers to frequently asked questions.

1. Open-end wrenches: classic for open nuts

The open-end wrench is the most common and recognizable type. Its main feature is open jaws that cover the nut or bolt on both sides. This design allows you to quickly put the wrench on the fastener, but it also has disadvantages: with strong force, the jaws can “break off,” damaging the edges of the nut.

These wrenches are usually used for work that does not require much force: tightening battery terminals, fastening pipes, fixing decorative elements. In automotive repair, open-end wrenches are often used to first loosen nuts before using a box or socket wrench.

• ✅ Pros: easy access to nuts in hard-to-reach places, low price, wide range of sizes.
• ❌ Cons: tendency to “break” from the nuts under strong force, not suitable for working with rounded or damaged edges.
• 🔧 Typical Application: fastening the battery terminals, fixing the clamps, adjusting the clutch cables.

⚠️ Attention: Never use an open-end wrench to unscrew stuck or rusted nuts - this is almost guaranteed to tear off the edges. In such cases, first treat the fastener with a penetrating lubricant (for example, WD-40 or Liqui Moly MoS2) and let stand for 10-15 minutes.

2. Spanners: reliability and edge protection

Socket wrenches, unlike open-end wrenches, have a closed loop (ring) that completely surrounds the nut or bolt head. This provides two key advantages: firstly, uniform force distribution along all edges, which reduces the risk of damage. Secondly, ability to work in confined spaces, where you simply can’t get an open-end wrench.

Auto mechanics often use box wrenches to work on the suspension, brake system, and engine. For example, for unscrewing wheel bearing nuts or shock absorber mounts. They are also indispensable when working with aluminum or soft alloys, where it is important not to damage the edges.

• 🔩 Types of spanners:
  • 🔹 Hexagonal - Standard for most metric and imperial nuts.
  • 🔹 Twelve-sided — allow you to turn the key to a smaller angle (30° instead of 60°), which is convenient in cramped conditions.
  • 🔹 With ratchet mechanism — combine the advantages of a spanner and a ratchet.

Key type	Max. rotation angle	Suitable for	Price (from/to, rub.)
Hex Socket	60°	Standard nuts, bolts	150–800
Twelve-sided cap	30°	Working in hard-to-reach places	300–1200
Snap-on with ratchet mechanism	5°–15°	Quick unscrewing/twisting	500–2500

When choosing a spanner wrench, pay attention to ring wall thickness. The larger it is, the higher the strength of the key, but also the less space for working in cramped conditions. The best option is keys with thin walls (the so-called "thin-walled"), which are suitable for most auto repair tasks.

3. Socket wrenches and sockets: for high torque applications

Socket wrenches (or sockets) are used in conjunction with wrenches, ratchet handles, or torque wrenches. Their main advantage is the ability to transmit high torque without the risk of damage to the edges. This makes them indispensable for working with wheel bolts, cylinder head fastenings, flywheels and other critical components.

Heads come in different types: hexagonal (standard for most bolts), twelve-sided (for working in confined spaces), star-shaped (Torx, E-Torx) (for modern cars), and also special (for example, for spark plug wells).

• 🔧 Types of gates:
  • 🔹 Straight knob - for standard work.
  • 🔹 L-shaped knob - Convenient for tightening with force.
  • 🔹 Ratchet wrench — allows you to quickly unscrew/tighten without rearranging.
  • 🔹 Extension Cords - for working in deep wells (for example, candle wells).

When purchasing socket heads, pay attention to material (better - chrome vanadium steel) and number of ratchet teeth (the more, the smoother the operation). For a car service, the best option is a set of sockets with a pitch of 1 mm (for example, from Hazet, Stahlwille or King Tony).

⚠️ Attention: Never use wrench extensions when using a torque wrench as this will distort the torque reading. If you need to tighten the nut in a deep well, first tighten it with a torque wrench without an extension, and then tighten it by hand.

Metric sockets (8-24mm in 1mm increments)|Inch sockets (1/4"-1")|Extensions (50mm, 100mm, 200mm)|Ratchet wrench (1/2")|1/4" adapter-->

4. Adjustable (adjustable) wrenches: versatility or compromise?

An adjustable wrench is a tool with adjustable jaw spacing, allowing it to be used for different sized nuts. The most famous models - Swedish key (with worm gear) and french key (with parallel jaws).

Main advantage - versatility: one key replaces the whole set. However, adjustable wrenches also have serious disadvantages: low accuracy (you can tear off the nut due to a loose fit), limited maximum torque (not suitable for strong tightening) and risk of edge damage soft metals.

• ✅ When to use:
  • 🔧 For emergency workwhen you don’t have the right size key at hand.
  • 🔧 For nuts with non-standard sizes (for example, on imported equipment).
  • 🔧 For plumbing work (if the key is not a car repair key).
• ❌ When NOT to use:
  • 🚫 For critical fastenings (hub nuts, cylinder head).
  • 🚫 For aluminum or soft nuts.
  • 🚫 For high force work.

If you still decide to buy an adjustable wrench for your car, choose models with parallel jaws (for example, Knipex Pliers Wrench or Bahco 8262). They provide a more even distribution of force and less damage to the edges.

How to properly set an adjustable wrench?

Before use, adjust the gap between the jaws so that the wrench fits snugly on the nut. no play, but did not require effort when putting it on. After work, slightly loosen the adjusting screw - this will extend the service life of the mechanism.

5. Combination keys: two in one

Combination wrenches combine an open-end and a socket end. Typically, there is an open part at one end (like an open-end wrench), and a closed ring at the other end (like a socket wrench). This allows you to use one tool for different tasks: for example, loosen a nut with the open-end end, and then tighten it with the union end.

Such keys are especially convenient for mobile sets, where it is important to save space. They are also useful when working with fasteners where one side of the nut is accessible to a box-end wrench, but the other side is only accessible to an open-end wrench (for example, in a car suspension).

• 🔧 Advantages of combination keys:
  • 🔹 Space saving — one key replaces two.
  • 🔹 Versatility - Suitable for different types of nuts.
  • 🔹 Convenience - no need to constantly change tools.
• 🔧 Disadvantages:
  • 🔹 Less strength compared to individual spanners.
  • 🔹 It is not always convenient to work in cramped conditions.

When choosing a combination key, pay attention to metal quality (better - chromium vanadium) and handle ergonomics (ribbed or rubberized surface prevents slipping). Good options are the keys to Hazet, Stahlwille or Gedore.

6. Special keys: for non-standard tasks

In addition to standard keys, specialized tools are often used in auto repair. They are designed to work with unusual fasteners or in specific conditions. Here are the most common types:

• 🔧 Spark plug keys:
  • Have rubber or magnetic retainer to hold the candle.
  • Often equipped extended knob for working in deep wells.
  • Example: Hazet 4762-1 or Stahlwille 720.
• 🔧 Oil filter wrenches:
  • There may be chain, tape or cup-shaped.
  • Example: Knipex 97 52 18 (tape) or King Tony 1002 (cup-shaped).
• 🔧 Torx and E-Torx keys:
  • Used for star bolts (for example, in airbags, car electronics).
  • Example: set Wera 05059051001.
• 🔧 Pulley wrenches and crankshaft nuts:
  • Have increased length to create high torque.
  • Often equipped hole for a crowbar for fixation.

Special wrenches are usually more expensive than standard wrenches, but their purchase is worth it if you regularly deal with related tasks. For example, oil filter wrench costs about 1000–2000 rubles, but it will save you from problems when changing the oil, especially if the filter is too tight.

When working with specialized keys, always follow the manufacturer's instructions. For example, when using oil filter chain puller Make sure that the chain fits tightly around the filter housing, otherwise it may come off and damage adjacent parts.

7. How to choose a quality wrench: 5 criteria

The quality of the key directly affects the result of work and security. A cheap tool can break at the most crucial moment or damage the fasteners. Here's what to look for when purchasing:

1. Material:

   The best option is chrome vanadium steel (designation Cr-V or CrMoV). It is durable, resistant to corrosion and can withstand high loads. Cheap carbon steel wrenches wear out and break quickly.

2. Metal thickness:

   The walls of the key should be thick enough, but not excessively - this is a balance between strength and access to tight spaces. For example, for ring wrenches, the wall thickness of the ring should be at least 3–4 mm.

3. Coverage:

   Chrome or nickel plating protects against corrosion and makes cleaning easier. Matte finish (eg. phosphating) is often used on professional wrenches for better grip.

4. Ergonomics:

   The handle should be comfortable, with rubberized inserts or corrugation to prevent slipping. Some keys (for example, Wera Kraftform) the handle has an anatomical shape.

5. Standard Compliance:

   Quality keys meet standards DIN (Germany), ANSI (USA) or GOST (Russia). For example, DIN 3110 - standard for open-end wrenches, DIN 3113 - for caps.

Don't buy keys by eye - always check them by weight (a quality instrument is heavier) and bending (cheap keys bend even with a little effort). Also pay attention to size marking — it should be clear and not fade over time.

8. Care and storage: how to extend the life of the instrument

Even the best quality key will not last long if it is not properly cared for. Basic rules:

• 🧹 Cleaning:
  • After work, remove dirt and oil traces dry cloth.
  • For heavy soiling, use kerosene or special cleaners (for example, WD-40 Specialist Cleaner).
  • Do not use abrasive materials (sandpaper, metal brushes) - they damage the coating.
• 💧 Corrosion protection:
  • Keep your keys in dry place (moisture causes rust).
  • Lubricate the tool periodically thin layer of oil (for example, Liqui Moly LM 40).
  • Avoid storing keys in plastic bags — condensation accelerates corrosion.
• 📦 Storage:
  • Use cases with cells or perforated panels for hanging storage.
  • Don't throw away the keys in bulk in a box - this leads to scratches and deformation.
  • Place the tool so that it is not came into contact with other metal objects (for example, hammers or chisels).

If the key is still rusty, clean it soft copper brush and apply a protective coating (eg tool lubricant or wax). Heavy rust can be removed acetic acid (immerse the key for 10-15 minutes, then wipe and dry).

⚠️ Attention: Never use wrenches as a hammer or lever - this leads to deformation and cracks. Also avoid overloads: If the wrench fails to engage the nut, do not try to increase the force with the pipe. Instead, use a more suitable tool (such as a long-wrench socket).

FAQ: Answers to frequently asked questions

🔧 Which key is better: open-end or cap?

It depends on the task:

• Rozhkovy convenient for quickly loosening nuts in accessible places, but not suitable for strong tightening.
• Cap more reliable, since it completely covers the nut and does not tear off the edges. It is preferable for critical fastenings.

For versatility, choose combination keys.

🔧 Is it possible to use an adjustable wrench to unscrew the hub nut?

No! The wheel nuts are tightened to a very high torque (usually 200–300 Nm), and the adjustable wrench will either fail or damage the nut. For this task you need special socket wrench (usually 30 or 32 mm) with a long wrench or a torque wrench.

🔧 Which key material is the most durable?

The strongest keys are made from chrome vanadium steel (Cr-V) or chrome molybdenum steel (Cr-Mo). They withstand high loads and are resistant to wear. There are also keys from titanium alloys, but they are more expensive and are not always justified for household use.

🔧 How to convert inch key sizes to metric?

For an approximate translation, use the table:

Inches	Millimeters
1/4"	6.35 mm
5/16"	7.94 mm
3/8"	9.53 mm
7/16"	11.11 mm
1/2"	12.70 mm

For an accurate selection, use combination wrench set with inch and metric sizes.

🔧 Why does the key “lick” the edges of the nut?

This happens for several reasons:

• Incorrect key size (too big or small).
• Use an open-end wrench to tighten tightly.
• Poor quality metal of the key or nut.
• Corrosion or contamination on the edges of the nut.

To avoid the problem, use spanner or socket wrench, having previously cleaned the nut of rust and lubricated it with a penetrating compound (for example, WD-40).