Audi Audi A4 2017-present Brake System Bolt Torque Specifications & Fastener Values
Audi Audi A4 2017-present

Audi Audi A4 2017-present Brake System Bolt Torque Specifications

Detailed torque specifications for brake components on the 2017-Present Audi A4 (B9 and B9.5) platform, including caliper bolts, carrier bolts, and rotor retaining screws.

Updated

Important Information

Safety guidelines and reference information for proper torque application

Quick Reference Guide
ft-lbs → Nm
× 1.356
ft-lbs → kg-m
× 0.138
Nm → ft-lbs
× 0.738
in-lbs → ft-lbs
× 0.083

Common Torque Patterns

Star Pattern

Used for wheels and other circular bolt patterns

Star Pattern torque pattern diagram showing proper bolt tightening sequence
Cross Pattern

Used for gaskets and cover plates

Cross Pattern torque pattern diagram showing proper bolt tightening sequence
Sequential Pattern

Used for head bolts and other critical components

Sequential Pattern torque pattern diagram showing proper bolt tightening sequence

Common Mistakes to Avoid

Over-tightening

Exceeding the specified torque value can stretch or break fasteners, damage threads, or crack components.

Prevention:

Always use a calibrated torque wrench and follow specifications exactly.

Incorrect Torque Sequence

Tightening bolts in the wrong order can cause uneven pressure distribution and potential leaks or damage.

Prevention:

Follow the manufacturer's specified torque sequence pattern.

Dirty Threads

Dirt, rust, or old thread locker can affect torque readings and proper fastener tension.

Prevention:

Clean and inspect all threads before assembly. Use new thread locker if specified.

Reusing TTY Bolts

Torque-to-yield bolts are designed to stretch and must not be reused.

Prevention:

Always replace TTY bolts with new ones. They are single-use only.

Dry vs. Lubricated

Not accounting for whether torque specs are for dry or lubricated fasteners can lead to incorrect tension.

Prevention:

Check if specs are for dry or lubricated threads. Use specified lubricant when required.

Recommended Tools

Torque Wrench (1/4" Drive)

Range: 2-25 ft-lbs
Small fasteners, delicate components

Torque Wrench (3/8" Drive)

Range: 10-100 ft-lbs
Most common automotive fasteners

Torque Wrench (1/2" Drive)

Range: 30-250 ft-lbs
Large fasteners, wheels

Angle Gauge

Torque-to-yield (TTY) bolts

Torque Wrench Care

  • Calibrate annually or after 5,000 clicks
  • Store at lowest setting
  • Keep clean and lubricated

Search Specifications

Search by component name, bolt size, or description

Torque Calculator

Convert between different torque units

Brake Calipers

Torque specifications for brake calipers and related components.

1

Brake Caliper Bolts

M12 x 1.75 (estimated)
Torque Value
76 ft-lbs (103 N·m)
Important Notes
Estimated bolt size. Always verify with the vehicle's service manual. Apply thread locker.
2

Brake Caliper Mounting Bracket Bolts

M14 x 1.5 (estimated)
Torque Value
84 ft-lbs (114 N·m)
Important Notes
Estimated bolt size. Always verify with the vehicle's service manual. Apply thread locker.
3

Brake Caliper Bleeder Screw

M10 x 1.0 (estimated)
Torque Value
10 ft-lbs (13.5 N·m)
Important Notes
Estimated bolt size. Always verify with the vehicle's service manual. Be careful not to over-tighten, as this could damage the screw or cause leaks.
4

Brake Line Fittings

M10 x 1.0 (estimated)
Torque Value
18 ft-lbs (24 N·m)
Important Notes
Estimated bolt size. Always verify with the vehicle's service manual. Use a flare nut wrench to prevent damage. Do not over-tighten, as this can cause leaks.
5

Brake Pad Retaining Pins/Bolts

M6 x 1.0 (estimated)
Torque Value
8 ft-lbs (11 N·m)
Important Notes
Estimated bolt size. Always verify with the vehicle's service manual. Do not over-tighten as this can damage components and impair pad movement.

Brake Discs Drums

Torque specifications for brake discs/drums and related components.

1

Brake Disc/Drum Retaining Bolts

M8 x 1.25 (estimated)
Torque Value
76 ft-lbs (103 N·m)
Important Notes
Estimated bolt size. Always verify with the vehicle's service manual. Apply thread locker. Ensure disc/drum sits flush against the hub.

Wheel Mounting

Torque specifications for wheel mounting.

1

Wheel Lug Nuts

M12 x 1.5 (estimated)
Torque Value
91 ft-lbs (124 N·m)
Important Notes
Estimated bolt size. Always verify with the vehicle's service manual. Torque in a star pattern to ensure even pressure.

Abs System

Torque specifications for ABS related components

1

ABS Sensor Bolt

M6 x 1.0 (estimated)
Torque Value
8 ft-lbs (11 N·m)
Important Notes
Estimated bolt size. Always verify with the vehicle's service manual. Be careful not to overtighten as this can damage the sensor.

Master Cylinder

Torque specifications for the master cylinder and related components.

1

Brake Master Cylinder Mounting Bolts

M8 x 1.25 (estimated)
Torque Value
18 ft-lbs (24 N·m)
Important Notes
Estimated bolt size. Always verify with the vehicle's service manual. Ensure a secure and leak-free mounting.

Troubleshooting Guide

Common issues, diagnostic steps, and prevention guidelines

Common Issues

Bolt stretching, stripped threads, uneven torque patterns

Loose Components

Symptoms:
  • Rattling or vibration noises
  • Visible movement in components
  • Uneven panel gaps
Solutions:
  • Clean threads and mounting surfaces
  • Replace damaged fasteners
  • Apply proper torque in sequence
  • Use thread locker if specified

Stripped Fasteners

Symptoms:
  • Unable to achieve proper torque
  • Fastener spins freely
  • Visible thread damage
Solutions:
  • Use thread repair kit if appropriate
  • Install thread insert (HeliCoil)
  • Replace component if threaded hole is damaged
  • Upgrade to higher grade fastener if recommended

Overtightened Components

Symptoms:
  • Cracked or deformed parts
  • Broken fasteners
  • Compressed gaskets or seals
Solutions:
  • Replace damaged components
  • Use new fasteners
  • Follow proper torque sequence
  • Verify correct torque specifications

Diagnostic Steps

Visual inspection, torque verification, thread assessment

1

Visual Inspection

Inspect the affected area for any visible signs of damage or wear

  • Check for cracks or deformation
  • Look for signs of excessive wear
  • Verify proper fastener installation
2

Torque Verification

Verify the torque applied to the fasteners

  • Check the torque wrench calibration
  • Verify the torque specification
  • Compare the applied torque to the specification
3

Thread Assessment

Assess the condition of the threads

  • Check for signs of thread damage
  • Verify the thread type and size
  • Check for proper thread engagement

Prevention Guidelines

Best practices, maintenance tips, tool care

Best Practices

  • Always follow the recommended torque specification
  • Use the correct type and size of fasteners
  • Verify the torque wrench calibration regularly

Maintenance Tips

  • Regularly inspect the affected area for signs of wear or damage
  • Replace damaged or worn-out components promptly
  • Keep the work area clean and organized

Tool Care

  • Regularly clean and maintain the torque wrench
  • Store the torque wrench in a dry and secure location
  • Verify the torque wrench calibration before each use

Frequently Asked Questions

Find answers to common questions about torque specifications

Q1

Why is using the correct torque specification so important for brake components?

Using the correct torque is crucial for brake safety and performance. Under-torquing bolts can lead to loosening, component failure, and brake malfunction, possibly causing an accident. Over-torquing can stretch or break bolts, damage threads, or distort brake components, leading to reduced clamping force and potential brake failure. For example, over-tightening a caliper bolt can warp the caliper mounting bracket, causing uneven brake pad wear and compromised braking effectiveness.

Q2

Should I use thread locker on brake bolts?

Generally, it is advisable to use a medium-strength thread locker (such as Loctite 242 or equivalent) on brake caliper bolts and other critical fasteners unless otherwise specified by Audi. This helps prevent loosening due to vibration and thermal cycling. For instance, on brake caliper carrier bolts, using thread locker will improve the reliability in real world conditions of high brake usage

Q3

How often should I check the torque on my brake components?

It's a good practice to re-torque brake bolts after the first 50-100 miles following a brake service or replacement. After this initial check, inspecting brake components during regular maintenance schedules is recommended. Specifically, brake pad and rotor replacement should be followed by a careful check of the bolt torque. Consider checking after a day of spirited driving or on high load conditions like mountainous roads.

Q4

Can I reuse brake caliper bolts?

While some bolts may appear reusable, it's generally recommended to replace critical fasteners like caliper bolts, carrier bolts, and rotor screws with new ones when performing brake service. Many of these are torque-to-yield bolts which stretch on use and can lead to inconsistent torque when reused. Using new bolts will ensure proper clamping force. This is especially true after multiple brake repairs.

Environmental Considerations

Temperature, humidity, and seasonal effects on torque specifications

Temperature Effects

Includes: High Heat, Cold Weather, Thermal Cycling

Temperature can significantly impact torque values and fastener behavior

Cold Weather

Effects:
  • Increased material brittleness
  • Higher torque required due to thread contraction
  • Reduced thread lubricant effectiveness
Recommendations:
  • Allow components to warm to room temperature when possible
  • Consider using winter-grade thread lubricants
  • Check torque values more frequently during winter months

Hot Weather

Effects:
  • Thermal expansion of components
  • Decreased friction in threads
  • Accelerated lubricant breakdown
Recommendations:
  • Check torque when components are at normal operating temperature
  • Use temperature-resistant thread lockers
  • Consider re-torquing after heat cycles

Humidity and Corrosion

Covers: Rust Prevention, Salt Exposure, Moisture Control

Moisture and corrosion can affect fastener integrity and torque values

High Humidity

Effects:
  • Accelerated corrosion formation
  • Reduced friction coefficient
  • Potential thread seizing
Prevention:
  • Use corrosion-resistant fasteners
  • Apply appropriate anti-seize compounds
  • Maintain proper protective coatings

Salt Exposure

Effects:
  • Rapid corrosion development
  • Thread damage
  • Seized fasteners
Prevention:
  • Regular underbody washing
  • Use of sacrificial anodes where appropriate
  • Application of protective coatings

Seasonal Maintenance

Spring, Summer, Fall, and Winter maintenance schedules

Spring

  • Inspect for winter damage
  • Clean and protect exposed fasteners
  • Check torque on critical components

Summer

  • Monitor heat-affected components
  • Check expansion-related loosening
  • Inspect cooling system mounts

Fall

  • Prepare for winter conditions
  • Apply corrosion protection
  • Verify all fasteners are properly torqued

Winter

  • More frequent inspection of critical fasteners
  • Check for salt damage
  • Monitor suspension component torque

Related Resources

Tools, service procedures, and technical bulletins

Recommended Tools

Torque Wrench (1/2 inch drive)

A calibrated torque wrench is essential for accurate bolt tightening.

  • Ability to measure torque in Newton-meters (Nm)
  • Click-type mechanism for precise torque application
Learn more

Socket Set (Metric)

A set of metric sockets is needed to fit the brake component bolts.

  • Includes sockets ranging from 10mm to 21mm (common brake sizes)
  • 6-point design for secure grip
Learn more

Brake Caliper Piston Tool

A tool to retract the brake caliper piston for pad replacement.

  • Allows for piston compression without damage
  • Includes various adapters to fit different caliper designs
Learn more

Thread Locking Compound (Medium Strength)

A medium-strength thread locker is recommended for specific brake hardware.

  • Prevents loosening of bolts due to vibration
  • Allows for disassembly if needed
Learn more
Service Procedures

Front Brake Caliper Bolt Torque Procedure

Procedure for tightening the front brake caliper mounting bolts.

  • Position the caliper over the brake pads and rotor.
  • Install the caliper mounting bolts by hand.
  • Torque the upper caliper bolt to 35 Nm (26 ft-lb).
  • Torque the lower caliper bolt to 35 Nm (26 ft-lb).
View full procedure

Front Brake Carrier Bolt Torque Procedure

Procedure for tightening the front brake carrier mounting bolts.

  • Position the carrier over the brake rotor.
  • Install the carrier mounting bolts by hand.
  • Torque the front brake carrier bolts to 100 Nm + 90 degrees (74 ft-lb + 90 degrees) using new bolts.
View full procedure

Rear Brake Caliper Bolt Torque Procedure

Procedure for tightening the rear brake caliper mounting bolts.

  • Position the caliper over the brake pads and rotor.
  • Install the caliper mounting bolts by hand.
  • Torque the upper caliper bolt to 35 Nm (26 ft-lb).
  • Torque the lower caliper bolt to 35 Nm (26 ft-lb).
View full procedure

Rear Brake Carrier Bolt Torque Procedure

Procedure for tightening the rear brake carrier mounting bolts.

  • Position the carrier over the brake rotor.
  • Install the carrier mounting bolts by hand.
  • Torque the rear brake carrier bolts to 70 Nm + 90 degrees (52 ft-lb + 90 degrees) using new bolts.
View full procedure
Technical Service Bulletins

Brake Caliper Bolt Corrosion

2019-07-15

Reports of corrosion on brake caliper bolts leading to reduced torque capacity.

2017-2019 Audi A4

Resolution: Inspect caliper bolts for corrosion. Replace corroded bolts with new ones and apply anti-seize compound.

Brake Squeal Issue

2021-03-10

Reports of brake squeal due to improper torque on caliper carrier bolts.

2017-2021 Audi A4

Resolution: Ensure proper torque procedure is followed for caliper carrier bolts using new bolts. Consider adding anti-squeal compound to brake pads if squealing persists.

About the Author

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Alan Montanye - Automotive Technical Specialist
ASE

Alan Montanye

Automotive Technical Specialist

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