What is the bolt size for a brake caliper?

There is no universal bolt size for brake calipers. The mounting bolts and guide pins vary by vehicle and caliper design. In practice, you’ll typically encounter metric bolts such as M8, M10, or M12 (often M10x1.5 or M12x1.75) and, on older American-made cars, imperial sizes like 7/16-20 or 1/2-20. The exact size and pitch depend on the make, model, and braking system, so always verify against the official service manual or OEM hardware before replacement.

Why bolt size varies

Brake calipers are designed to fit a specific caliper bracket or knuckle pattern, and the size of the mounting bolts helps ensure proper alignment, torque retention, and safety. Different car brands, generations, and braking systems use different thread types and lengths. Always rely on the manufacturer specification to avoid under- or over-sizing, which could compromise braking performance.

Common bolt size ranges

Here are typical sizes you may encounter, depending on whether your vehicle uses metric or imperial hardware and whether you're dealing with front mounting bolts or rear caliper hardware.

• Metric mounting bolts: commonly M8, M10, or M12 diameters. Typical thread pitches include 1.25, 1.5, or 1.75; lengths commonly range from about 20 to 40 mm depending on vehicle.


• Imperial mounting bolts: common sizes include 7/16-20 UNC and 1/2-20 UNC, with lengths varying by application.


• Rear caliper and guide-pin bolts: sizes often mirror front mounting bolts in metric or imperial forms, but exact pitch and length vary by model; always verify.

Note: The exact bolt size for your vehicle is specified in the service manual and OEM parts catalogs; using the wrong size can cause improper seating, torque loss, or brake failure.

How to identify the correct bolt size for your vehicle

To identify the exact bolt size for your brake caliper, follow these steps:

1. Check the vehicle's service manual or the OEM parts catalog for the recommended caliper mounting bolts for your model.


2. Inspect the existing bolts: measure the bolt diameter with a caliper, determine thread pitch with a thread gauge, and note the bolt length.


3. If replacing with aftermarket bolts, ensure you are buying the correct size by providing your vehicle information and caliper type to the supplier.


4. Verify torque specs in the manual and determine whether threadlocker is required for the mounting bolts; apply as specified.


5. Install with the correct sequence, ensure the caliper sits properly on the bracket and slides freely, and torque to the specified value.

Accurately identifying the size and using the correct torque specification are essential for safe brake operation and to prevent caliper misalignment or rotor wear.

Choosing the right bolts and installation tips

Strength grade and material

Brake caliper bolts are typically high-strength steel and may be rated for high torque. Use bolts of the grade recommended by the manufacturer (often through bolts rated at grade 10.9 or higher) to maintain clamping force and avoid shear failure.

Torque and retention guidelines

Follow the manual for torque values and whether a threadlocker is required on mounting bolts. Improper torque can lead to rotor runout, caliper misalignment, or bolt loosening.

When in doubt, consult a professional or the dealership's service department for model-specific guidance to ensure you select the correct bolt size and installation procedure.

Summary

Brake caliper bolt sizes are not standardized across all vehicles. The right bolts depend on the car’s make, model, year, and braking system. Expect metric bolts (commonly M8–M12) or imperial sizes (such as 7/16-20 or 1/2-20) and always confirm with the service manual or OEM parts catalog. Accurate identification, correct length and pitch, and proper torque are essential for safe braking performance.

What size socket for brake caliper bolts?

The socket size for brake caliper bolts varies by vehicle, but common metric sizes are 13mm, 14mm, 15mm, 17mm, and 18mm. Caliper bracket bolts can also be a different size, such as 18mm or 19mm, and some cars use specialty sockets like Allen (hex), Torx, or 10-point sockets. Always check your vehicle's service manual for the exact size.
 
This video demonstrates how to locate and remove caliper bolts: 56sExpertVillage Leaf GroupYouTube · May 9, 2007
Common socket sizes

• Caliper mounting bolts: Common sizes include 13mm, 14mm, 15mm, 17mm, or 18mm. 
• Caliper bracket bolts: These are often larger and can be 18mm or 19mm. 
• Specialty bolts: Some calipers use different bolt types, including: 
  • Allen (hex): Common sizes like 7mm or 8mm are used, especially on European cars. 
  • Torx: Less common, but some vehicles use Torx bits. 
  • 10-point: Found on some specific models. 

This video shows how to replace brake calipers and the associated bolts: 55sTRQYouTube · Apr 3, 2025
How to determine the correct size

1. Check your owner's manual: This is the most reliable way to find the exact size for your vehicle. 
2. Visually inspect the bolt head: Look to see if it's a standard 6-point socket, an Allen head, a Torx, or a 10-point bolt. 
3. Use a socket set to test: If you're unsure, try a few common metric sizes. Be careful not to strip the bolt if the size is incorrect. 

You can watch this video to see how to replace brake caliper mounting bolts: 56sTRQYouTube · Jul 19, 2022

What is a brake caliper bracket bolt?

A brake caliper bolt, also known as a caliper slide bolt or guide pin bolt, is a threaded fastener that attaches the brake caliper to the steering knuckle or caliper bracket. It holds the caliper in place while still allowing it to slide laterally as the brake pads engage and disengage with the rotor.

What size is a brake caliper bolt?

There is no single universal size for brake caliper bolts; they vary by vehicle, so you must confirm the size for your specific make and model. For example, some vehicles use an M12 x 1.50 x 65mm bolt, while others might use a 7/16-inch fine thread or an M14-2.0 bolt. Common sizes can include M10, M12, or M14, with various lengths and thread pitches depending on the application. 
How to find the correct size

• Check your vehicle's manual: Your owner's manual may have a list of specifications or can point you toward the correct part number. 
• Use a parts catalog: Use an online or physical auto parts catalog by entering your vehicle's year, make, and model to find the correct part number. Sites like O'Reilly Auto Parts or even parts listings for specific makes like Toyota or Volkswagen can provide detailed specifications. 
• Inspect the old bolt: If you have the original bolt, measure its diameter, length, and thread pitch (threads per inch or metric pitch). 
• Count the threads: For a quick check, you can manually count the number of threads within a given length to find the thread pitch. 
• Consult a professional: If you are unsure, a professional mechanic can accurately identify the correct size and grade for your vehicle.

Common sizes and examples

• M12 x 1.50 x 65mm: Used on the rear caliper bracket mounting bolt for some Volkswagen Jettas. 
• 7/16" Fine Thread: Used on some GM caliper bracket brake bolts. 
• M14-2.0: A common brake caliper bracket bolt size, often with an 18mm hex head. 
• M12-1.25: Another common size for brake caliper bracket bolts, often around 46mm or 40mm in length. 

Are brake caliper bolts universal?

No, brake caliper bolts are not universal, as they vary significantly in size, thread pitch, and grade depending on the vehicle's make, model, and whether they are for the caliper bracket or the caliper itself. You must use the correct bolts for your specific vehicle to ensure proper and safe braking performance. 
This video explains the importance of inspecting and replacing brake caliper bolts: 1mMercedessourceYouTube · Jan 22, 2018
Why brake caliper bolts aren't universal

• Vehicle-specific design: Different cars have different caliper designs and mounting requirements, so bolts made for one may not fit another. 
• Different bolt types: Vehicles have multiple types of caliper bolts, such as the larger ones that secure the caliper bracket to the steering knuckle and the smaller ones that attach the caliper to the bracket. These different bolts have different specifications and tightening requirements. 
• Varying specifications: The correct bolt needs to match the vehicle's specifications, including the size, thread, and material grade, which is crucial for safety. 
• Replacement parts: Even aftermarket or replacement caliper brackets may come with different-sized bolts than the original ones. 

What to do instead

• Consult your vehicle's service manual: This is the most reliable way to determine the correct bolt specifications for your specific vehicle. 
• Buy parts from a reputable source: When replacing your brakes, it is best to buy a complete brake kit for your vehicle or a caliper mounting hardware kit specifically designed for your make and model. 
• Use the correct torque: When installing, ensure you use the correct torque specifications for the bolts, as over-tightening can also be a problem.