Mercedes-Benz Mercedes A-Class 2004-2012 Brake System Bolt Torque Specifications & Fastener Values
Mercedes-Benz Mercedes A-Class 2004-2012

Mercedes-Benz Mercedes A-Class 2004-2012 Brake System Bolt Torque Specifications

Detailed torque specifications for brake components on the 2004-2012 Mercedes A-Class, including caliper bolts, carrier bolts, and brake line fittings.

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 caliper subsystem

Components related to the mounting and operation of the brake caliper.

1

Brake Caliper Bolts

M12 x 1.5
Torque Value
75 ft-lbs (100 N·m)
2

Brake Caliper Mounting Bracket Bolts

M14 x 1.5
Torque Value
129 ft-lbs (175 N·m)

Brake rotor/disc subsystem

Components related to the mounting and operation of the brake rotor or disc.

1

Brake Disc/Drum Retaining Bolts

M10 x 1.25
Torque Value
59 ft-lbs (80 N·m)

Wheel and hub subsystem

Components related to the mounting and operation of the wheel and hub.

1

Wheel Lug Nuts

M14 x 1.5
Torque Value
96 ft-lbs (130 N·m)

Brake master cylinder and booster subsystem

Components related to the mounting and operation of the brake master cylinder and booster.

1

Brake Master Cylinder Mounting Bolts

M10 x 1.25
Torque Value
20 ft-lbs (27 N·m)
Important Notes
Estimated value, may vary depending on specific application and manufacturer's recommendations.
2

Brake Booster Mounting Bolts

M10 x 1.25
Torque Value
20 ft-lbs (27 N·m)
Important Notes
Estimated value, may vary depending on specific application and manufacturer's recommendations.

Abs module and brake line subsystem

Components related to the mounting and operation of the ABS module and brake lines.

1

ABS Module Mounting Bolts

M8 x 1.25
Torque Value
20 ft-lbs (27 N·m)
Important Notes
Estimated value, may vary depending on specific application and manufacturer's recommendations.
2

Brake Line Fittings

M10 x 1.25
Torque Value
12 ft-lbs (16 N·m)
Important Notes
Estimated value, may vary depending on specific application and manufacturer's recommendations.

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

What is the recommended torque for brake caliper bolts on a 2004-2012 Mercedes A-Class?

The recommended torque for brake caliper bolts on a 2004-2012 Mercedes A-Class is typically 85 Nm (63 lb-ft). However, always refer to the vehicle's service manual or manufacturer specifications for the exact torque value, as it may vary depending on the specific model and brake system configuration.

Q2

How often should brake components be inspected for proper torque?

Brake components, including caliper bolts, should be inspected for proper torque during every brake service or tire rotation. Additionally, if you notice any unusual noises, vibrations, or braking performance issues, it is advisable to check the torque of all brake-related bolts immediately.

Q3

Can I reuse brake caliper bolts, or should they be replaced?

Brake caliper bolts are generally designed for single use and should be replaced after removal. Reusing old bolts can lead to improper torque application, which may result in brake failure. Always use new, manufacturer-approved bolts when reassembling the brake system.

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

A precision tool used to apply a specific torque to brake system bolts.

  • Adjustable torque settings
  • Calibrated for accuracy
Learn more

Brake Caliper Piston Tool

A tool used to retract brake caliper pistons during brake pad replacement.

  • Compatible with Mercedes A-Class calipers
  • Ergonomic design for ease of use
Learn more

Hex Socket Set

A set of hex sockets for removing and tightening brake system bolts.

  • Includes sizes for brake caliper bolts
  • Durable construction
Learn more
Service Procedures

Brake Caliper Bolt Torque Application

Procedure for correctly torquing brake caliper bolts on a 2004-2012 Mercedes A-Class.

  • Lift the vehicle and remove the wheel to access the brake caliper.
  • Use a hex socket to remove the caliper bolts.
  • Retract the caliper piston using a brake caliper piston tool.
  • Install new brake pads and reassemble the caliper.
  • Apply the specified torque to the caliper bolts using a torque wrench.
  • Reinstall the wheel and lower the vehicle.
View full procedure

Brake Disc Retaining Screw Torque Application

Procedure for torquing brake disc retaining screws on a 2004-2012 Mercedes A-Class.

  • Remove the wheel to access the brake disc.
  • Use a screwdriver or hex socket to remove the retaining screw.
  • Clean the hub surface and install the new brake disc.
  • Apply the specified torque to the retaining screw using a torque wrench.
  • Reinstall the wheel and lower the vehicle.
View full procedure
Technical Service Bulletins

Brake Caliper Bolt Loosening Issue

2010-05-15

Reports of brake caliper bolts loosening over time on certain 2004-2012 Mercedes A-Class models.

2004-2012 Mercedes A-Class

Resolution: Ensure proper torque application during brake service and use thread locker on caliper bolts as recommended.

Brake Disc Vibration and Noise

2011-08-22

Some 2004-2012 Mercedes A-Class models experience brake disc vibration and noise due to improper torque on retaining screws.

2004-2012 Mercedes A-Class

Resolution: Verify torque specifications for brake disc retaining screws and ensure proper installation during brake service.

About the Author

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Alan Montanye - Automotive Technical Specialist
ASE

Alan Montanye

Automotive Technical Specialist

ASE Master Certified Technician with over a decade of hands-on experience in automotive repair and diagnostics.

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