What size is the caliper bracket bolt?
There isn’t a single universal size for caliper bracket bolts—the correct size depends on the vehicle. In practice you’ll typically see metric bolts ranging from 8 to 12 mm in diameter (often M10 or M12) or imperial sizes like 5/16" to 3/8", with various thread pitches. Always verify using the vehicle’s service manual or by measuring the existing bolt.
The question concerns the fastener that secures the brake caliper to its mounting hardware on the wheel hub assembly. The exact diameter, pitch, and length vary by caliper design and vehicle model. Using the wrong bolt can compromise brake function and safety, so confirming the correct size before replacement is essential.
Why bolt size matters
Caliper mounting bolts are high‑tension fasteners that must fit snugly and thread into the caliper bracket or knuckle. An incorrect size can strip threads, leak brake fluid, or fail under braking loads. Always match the size, grade, and thread pitch specified by the vehicle manufacturer.
Typical size ranges you may encounter
Below are the size ranges you are most likely to encounter, broken into metric and imperial categories. These are common across many cars, but there are notable exceptions depending on make, model, and year.
- Metric bolts: commonly in the 8–12 mm diameter range. Typical thread pitches include M8x1.0 or M8x1.25, M10x1.25, and M12x1.25 or M12x1.75.
- Imperial bolts: commonly in the 5/16" to 3/8" diameter range, with thread pitches such as 5/16"-18, 3/8"-24, etc.
- Special cases: some models may use less common sizes or bolt spacings; always verify against the service manual or OEM hardware.
Concluding: Because sizes vary widely by model, the only reliable method is to confirm the exact bolt size for your vehicle and to use the correct torque specification when reinstalling.
How to determine the correct bolt size for your vehicle
To determine the correct size and specification for your caliper bracket bolts, follow these steps:
- Identify the bolt that secures the caliper bracket to the knuckle or caliper itself and locate the part number if possible.
- Measure the bolt's diameter by wrapping a caliper around the threads or using a precise ruler across the threaded portion.
- Determine the thread pitch by counting the number of threads in a given length (or using a thread pitch gauge). For metric bolts, record the pitch (e.g., 1.25 mm); for imperial bolts, count threads per inch (TPI).
- Inspect the bolt length to ensure it penetrates the bracket and threads adequately without bottoming out or leaving excess protrusion.
- Check the bolt grade and material; many brake fasteners are high-strength (e.g., Grade 8.8 or higher) and may use threadlocker as specified by the manufacturer.
- Consult the vehicle’s service manual or OEM parts catalog to confirm the exact size, pitch, length, and torque specification, and replace with an equivalent bolt if a direct replacement is not available.
Concluding: By measuring and cross-checking with official documentation, you can identify the precise caliper bracket bolt size for your car and maintain braking system integrity.
Summary
The size of caliper bracket bolts is not universal. Expect metric sizes from about M8 to M12 or imperial sizes from roughly 5/16" to 3/8", with various thread pitches. Always verify the exact specification for your vehicle through the service manual, OEM parts catalog, or by measuring the existing bolt, and torque to the manufacturer’s specification during reassembly to ensure safe braking performance.
What size is the rear caliper bracket bolt on a 2016 Jetta?
M12 x 1.5 x 65 mm
2006-2020 Volkswagen Jetta. Notes: Brake Caliper Bracket Mounting Bolt -- M12 x 1.5 x 65 mm. Position: Rear.
What size are caliper bracket bolts?
Product Specifications
| Bolt Grade: | 10.9 |
|---|---|
| Thread Diameter: | 13.71 mm |
| Thread Length: | 40.64 mm |
| Thread Type: | Coarse |
| Washers Included: | Yes |
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
- Check your owner's manual: This is the most reliable way to find the exact size for your vehicle.
- 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.
- 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
Are caliper mounting bolts universal?
OEM (Original Equipment Manufacturer) caliper bolts are designed to fit your vehicle's exact specifications, and using anything other than the correct bolts can compromise the integrity of the brake system.
