What Size Is the Bolt on the Audi Q5 Brake Caliper?

The most common Audi Q5 front brake caliper guide pin/slider bolts use a 7 mm internal hex (Allen) drive, while the caliper carrier (bracket) bolts typically use a 21 mm external hex head; however, bolt sizes can vary slightly by model year, engine, and whether you have standard or performance brakes, so you should always verify by checking a repair manual or the specific VIN-based parts catalog.

Why the Exact Caliper Bolt Size Is Not the Same for Every Audi Q5

The question “What size is the bolt on the Audi Q5 caliper?” seems straightforward, but the answer depends on several factors: the generation of the Q5, engine and brake package, and whether you mean the caliper guide pin bolts or the caliper carrier (bracket) bolts. Audi uses different brake setups across model years and trims, so there is no single universal bolt size that applies to every Q5 ever built.

Typical Caliper Bolt Sizes by Type

On most Audi passenger vehicles, including the Q5, each front brake assembly is held together by two main types of bolts: smaller guide pin (slider) bolts that allow the caliper to move, and larger carrier (bracket) bolts that fix the bracket to the steering knuckle. Understanding which is which helps you pick the correct tool and torque spec.

Guide Pin / Slider Bolts (Caliper-to-Bracket)

The slider bolts are the smaller fasteners you remove when doing a basic pad change, allowing the caliper to pivot or slide off the pads. These are designed for periodic removal and lubrication, so their tool size is standardized on many VAG (Volkswagen–Audi Group) vehicles.

The main characteristics of the Audi Q5 front caliper guide pin bolts are as follows:

• Typical drive size: 7 mm internal hex (Allen) on most Q5 front calipers.
• Common socket needed: 3/8″ drive 7 mm hex bit socket.
• Location: Two bolts per front caliper, accessed from the back of the caliper body.
• Thread size: Often M8 x ~1.25 (varies slightly by supplier), but you generally work by tool size, not thread spec.
• Use: Removed for pad replacement; usually reused if undamaged and if not designated as “always replace” in service data.

These slider bolts are what most DIY brake jobs involve, and in practice, a 7 mm hex is the tool size most Q5 owners and technicians encounter when removing the caliper from the carrier for pad changes.

Carrier / Bracket Bolts (Caliper Bracket-to-Knuckle)

The larger caliper carrier bolts secure the bracket to the steering knuckle and are generally not removed unless you are replacing the brake rotor or doing deeper service. These bolts see higher loads and are often stretch (torque-to-yield) fasteners on modern Audis.

For many Audi Q5 models, the carrier bolt details are:

• Typical head size (front): 21 mm external hex on many Q5 generations and engines.
• Typical head size (rear): Often in the 18–21 mm range depending on year and brake package.
• Thread size: Commonly in the M12 or M14 class; exact spec varies with caliper and rotor size.
• Torque spec behavior: Frequently one-time-use, torque-to-yield bolts specified by Audi to be replaced when removed.
• Access: Located behind the rotor area, typically two bolts per carrier.

Because these bolts are highly load‑bearing, Audi often issues strict torque and replacement guidelines, which means the correct tool size is just one part of doing the job safely.

Differences by Generation and Brake Package

The Audi Q5 has spanned several generations and facelifts since its launch in 2008, and brake component suppliers and sizes have shifted over time. That variation is why an exact, single-size answer is risky without specifying the model year and trim.

First Generation (8R, ~2009–2017)

On the original Q5 (chassis code 8R), covering late 2000s through mid‑2010s, the mainstream engines (2.0 TFSI, 3.2 FSI, later 3.0 TFSI diesels and gasoline engines) used similar brake layouts but with some variations in rotor size and caliper style.

Common patterns for 8R models include:

• Front guide pin bolts: 7 mm internal hex on the majority of standard single‑piston sliding calipers.
• Front carrier bolts: Typically 21 mm head; torque‑to‑yield bolts specified as “replace after removal” in many factory procedures.
• Rear caliper bolts: Often also 7 mm internal hex for the sliders, but rear carrier bolts may use slightly smaller heads (for example 18–19 mm) depending on the specific brake package.
• Performance or larger rotor packages: Some V6 or towing‑oriented setups may have beefier carriers, but the tool sizes remain close to these norms.

For most DIY first‑gen Q5 owners, a 7 mm hex bit and a 21 mm socket cover 90% of caliper bolt work, but exceptions exist.

Second Generation (FY, ~2018–present)

The second‑generation Q5 (chassis code FY) introduced weight saving and updated electronics, but basic brake architecture still relies on sliding calipers for most trims. Bolt sizing is broadly similar, though hardware suppliers vary.

Typical traits on many FY Q5 models include:

• Front caliper slider bolts: Still very commonly 7 mm internal hex, especially on standard single‑piston front calipers.
• Front carrier bolts: Frequently 21 mm external hex, with torque‑to‑yield specification and replacement recommended.
• Rear calipers (with electronic parking brake): Slider bolts often continue to use a 7 mm internal hex, while carrier bolts stay in the high‑teens to low‑20s mm head size range.
• SQ5 and larger-brake variants: May use different caliper and carrier designs with altered bolt head sizes; some sport packages use larger multi‑piston front calipers that may not follow the same 7 mm pattern.

In practice, most standard FY‑generation Q5s still respond to the same toolkit: a 7 mm hex bit for the caliper and roughly 21 mm for the carrier.

How to Confirm the Exact Bolt Size for Your Specific Q5

Because Audi’s hardware can vary by region, supplier, and special packages, the most reliable way to confirm the exact bolt size for your Q5’s caliper is to cross‑check with documentation tied to your VIN and visually confirm before starting work.

There are several practical steps you can take to verify the bolt size before disassembly:

• Check a factory or OEM‑quality repair manual: Audi’s ElsaWin or third‑party services like Alldata or Mitchell often list tool sizes and torque specs by VIN or model year.
• Use an OEM parts catalog: Audi’s online parts catalogs (via dealers or sites like parts.audiusa.com, or ETKA‑based tools) list the caliper and carrier fasteners; while they focus on thread size, you can often identify the part and cross‑reference to tool data.
• Inspect visually: With the wheel off, you can visually confirm whether the smaller bolts are internal hex (socket‑head) and estimate whether they match the common 7 mm size by trial-fitting a hex key.
• Test-fit tools gently: Try a 6 mm and 7 mm hex bit—if 6 mm feels loose and 7 mm fits snugly with no play, you’ve confirmed the 7 mm slider bolt. For carrier bolts, test a 19 mm, then 21 mm socket; the correct one should seat fully with no wobble.
• Consult a model‑specific forum or service bulletin: Enthusiast forums (e.g., AudiWorld, VWVortex, Audizine) often document exact sizes per model year and trim, especially when people share brake DIYs.

By combining a short visual inspection with reference material, you ensure you have the exact tools you need before attempting a brake job, reducing the risk of stripping a bolt or getting stuck mid‑repair.

Tools and Precautions When Working on Q5 Caliper Bolts

Knowing the size is only part of the job; using the right tools and following correct procedures matters just as much, particularly on a relatively heavy SUV like the Q5 where brakes run hot and hardware is heavily stressed.

Recommended Tools for Audi Q5 Caliper Bolts

To safely work on the brake caliper bolts of an Audi Q5, a basic but robust toolkit is required. The most important tools relate directly to the bolt sizes in question.

Key tools that typically match the Q5’s caliper hardware include:

• Hex bit sockets: 7 mm hex bit on a 3/8″ or 1/2″ drive for the slider bolts; some sets also include 6–10 mm sizes for verification.
• Large sockets: 21 mm 1/2″ drive socket for carrier bolts; have 19 mm and 18 mm on hand in case of package variations.
• Breaker bar: A long‑handled 1/2″ drive bar to release high‑torque carrier bolts.
• Torque wrench: A quality torque wrench capable of handling both low torque (slider bolts) and higher torque plus angle (carrier bolts if specified).
• Wire brush and brake cleaner: For cleaning bolt heads and the surrounding area so tools seat properly and torque readings are accurate.

Having the correct sizes available before lifting the vehicle reduces the chance of rounding fasteners and allows you to follow factory torque recommendations accurately.

Safety and Torque Considerations

Caliper fasteners are safety‑critical components. Over‑ or under‑tightening, or reusing bolts that Audi classifies as one‑time use, can compromise braking performance or lead to component failure.

The most important safety and torque practices include:

• Use the correct torque specifications: Factory repair data will specify torque values (often plus an angle) for carrier bolts and a simpler torque setting for slider bolts.
• Replace torque‑to‑yield bolts as required: If Audi labels carrier bolts as “always replace,” do not reuse them; the bolts stretch during tightening and may not hold torque if reused.
• Avoid impact guns on slider bolts: Impact tools can easily strip internal hex heads; use hand tools for precise control.
• Verify caliper movement after reassembly: The caliper should slide freely on the guide pins; seized pins can cause uneven pad wear and overheating.
• Test brakes before driving: After any brake work, pump the pedal to seat pads and confirm firm pedal feel before moving the vehicle.

Following these practices helps ensure that knowing the correct bolt size translates into a safe and successful brake service, rather than simply getting the hardware loose.

Bottom Line: What Size Bolt Does the Audi Q5 Caliper Use?

For the majority of Audi Q5 models, especially standard-brake versions of both first‑gen (8R) and second‑gen (FY) vehicles, the commonly encountered caliper bolt sizes are:

The two most relevant caliper fastener sizes on most Audi Q5s are:

• Caliper guide pin (slider) bolts: 7 mm internal hex (Allen) head.
• Caliper carrier (bracket) bolts: Approximately 21 mm external hex head, often torque‑to‑yield and specified as replace‑after‑removal.

These values will cover the typical toolbox needs for an Audi Q5 brake job, but because of variations by year and brake package, always verify against service data or your exact vehicle before relying on them.

Summary

Most Audi Q5 front brake calipers use 7 mm internal-hex slider bolts to attach the caliper to the bracket and roughly 21 mm external-hex carrier bolts to attach the bracket to the knuckle. These sizes are common across both first‑ and second‑generation Q5s with standard brakes, though performance variants and certain rear setups can differ. To be completely certain for your specific vehicle, check an Audi repair manual or VIN‑based parts catalog and confirm visually with the correct sockets and hex bits before performing brake work.

What size bolt is a brake caliper bolt?

There is no single brake caliper bolt size, as it varies significantly by vehicle make, model, and brake system configuration. Common sizes include M12 x 1.50 for mounting brackets, and smaller M6 or 7/16-inch bolts for securing the caliper itself, often requiring specific Allen or Torx heads. It is essential to check your vehicle’s specifications or consult a parts database for the correct size, length, and thread pitch. 
Common sizes by caliper type

• Caliper mounting bracket bolts: These are typically larger, heavy-duty bolts. 
  • M12 x 1.50 x 65mm: A common size for rear caliper mounting brackets on vehicles like a Volkswagen Jetta. 
  • 13mm to 17mm wrenches: Many front and rear caliper mounting bolts will require a wrench within this range, depending on the vehicle. 
• Caliper slide/guide bolts: These smaller bolts secure the caliper to the bracket. 
  • M6: Frequently used on mountain bikes and some bicycle disc brakes. 
  • 7/16-inch fine thread: A common size for GM vehicles, often using an Allen head. 

Important considerations

• Do not use a universal bolt: Brake caliper bolts are safety-critical. Using the wrong size or strength bolt can lead to brake failure. 
• Check your vehicle’s specifics: Always verify the correct bolt size, including thread pitch and length, for your specific vehicle before purchasing a replacement. 
• Look up the right part: You can often find the exact part number by using your vehicle’s year, make, and model on auto parts websites or by using a service manual. 

What size socket do I need to take off a brake caliper?

The socket size for removing a brake caliper varies by vehicle, but common sizes are 13mm, 14mm, 15mm, or 18mm. It is essential to check your vehicle’s service manual or a parts lookup for the exact size and type of socket needed for your specific model, as it could be a different metric size or a specialized one, like a 12-point, spline, or triple-square socket. 
This video shows how to remove caliper bolts on a Chevrolet Silverado: 53sTRQYouTube · Sep 26, 2024
Common socket sizes to consider

• 13mm, 14mm, 15mm: Frequently used for the caliper mounting bolts. 
• 18mm: Often used for the caliper mounting bracket bolts on some vehicles. 
• 19mm: Can be used for caliper mounting bracket bolts on certain models. 
• Specialized sockets: Some European and other vehicles may require specialized sockets, such as a 12-point 15mm socket, a 22mm 7-point socket, or a triple-head socket for the carrier bolts. 

Before you begin

• Identify the correct size: Always confirm the specific size for your make and model to avoid damaging the bolts. 
• Use the correct socket type: A 12-point socket is often recommended over a spline or star bit to prevent stripping the bolt head. 
• Leverage: A breaker bar or impact wrench may be needed for seized or tight bolts, as they are often extremely tight. 

What size wrench for caliper bolts?

The wrench size for caliper bolts varies by vehicle, but common sizes are 13mm, 15mm, or 17mm for caliper mounting bolts, and 7mm or 9mm for guide pin bolts, which may require an Allen or Torx bit. To be sure, it is best to check the vehicle’s manual, but having a set of common metric sockets is helpful.
 
This video demonstrates how to remove caliper bolts: 56sTRQYouTube · Apr 3, 2025

• Caliper mounting bolts: These are often 13mm, 15mm, or 17mm, with 15mm being a common size for many vehicles, notes JustAnswer and JustAnswer. 
• Caliper guide pin bolts: These are typically smaller and may require an Allen or Torx bit, such as 7mm or 9mm for an Allen head, or a T40 or T45 bit, as mentioned on iFixit. 
• For commercial vehicles: These can have much larger bolts that may require a 3/4″ drive slogging wrench, as seen in this Amazon.com product listing. 
• For banjo bolts: These require an 11mm or 15mm wrench, depending on the vehicle. 
• For a universal fit: Since sizes vary by manufacturer and model, it’s best to start with a metric wrench and socket set and have a variety of sizes on hand. 

What size allen key do I need to remove brake calipers?

The most common allen key size for removing brake calipers is 7mm, but it can vary by vehicle, so some cars may require other sizes like 8mm, 9mm, or 11mm. It is best to check your vehicle’s specific manual or look up the size for your make and model to ensure you have the correct allen key for the job, and consider getting a set of long or socket-style allen keys for easier access.
 
This video shows how to identify and remove the caliper mounting bolts on a Jeep Grand Cherokee: 58sTRQYouTube · May 8, 2024
Common sizes and why a specific one might be needed

• 7mm: This is the most frequently cited size for both front and rear calipers on many vehicles, such as BMWs and some Ford models. 
• 9mm: Some vehicles, particularly rear calipers, may use a 9mm allen key. 
• 8mm or 11mm: These sizes are also sometimes used, so it is essential to confirm the size for your specific vehicle to avoid stripping the bolt head. 

Tips for choosing the right tool

• Check your vehicle’s manual: The most accurate way to determine the correct size is to consult the service manual for your specific make and model. 
• Get a hex socket or long bit: Since caliper bolts can be in a recessed or tight spot, a standard L-shaped allen key might not fit. A hex socket or a long allen bit on a ratchet will provide better clearance and leverage. 
• Be prepared for variations: The size can differ between the front and rear brakes on the same vehicle. It is a good idea to have a range of common sizes on hand. 
• Consider the bolt condition: If the bolt is old or corroded, apply a penetrating oil and let it soak in to make removal easier. 

You can watch this video to learn how to remove the caliper mounting bolts on a Chevrolet Silverado: 43sTRQYouTube · Aug 8, 2023