Audi Audi A8 2002-2010 VL381 Transmission Transmission Torque Specifications & Bolt Torque Values
Audi Audi A8 2002-2010

Audi Audi A8 2002-2010 VL381 Transmission Torque Specifications

Detailed torque specifications for all bolts related to the VL381 transmission used in the 2002-2010 Audi A8 (D3) platform. Includes case bolts, valve body bolts, and other relevant fasteners.

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

Transmission Housing

Torque specifications for bolts related to the main transmission case and its attachments.

1

Bellhousing to Engine Bolts

M10 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
Estimated value based on similar Audi A8 applications. These bolts secure the transmission to the engine block.
2

Transmission Housing Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Industry standard value for M8 fasteners in aluminum housing. These bolts secure the main transmission case halves.
3

Transmission Oil Pan Bolts

M6 x 1.0
Torque Value
9 ft-lbs (12 N·m)
Important Notes
Industry standard value for M6 fasteners in aluminum pan. These bolts secure the transmission oil pan.

Mechatronic Valve Body

Torque specifications for bolts related to the valve body and mechatronic unit.

1

Valve Body to Transmission Housing Bolts

M6 x 1.0
Torque Value
9 ft-lbs (12 N·m)
Important Notes
Estimated value based on similar Audi model valve body M6 fasteners. These bolts secure the valve body to the transmission housing.
2

Mechatronic Unit to Valve Body Bolts

M5 x 0.8
Torque Value
6 ft-lbs (8 N·m)
Important Notes
Industry standard value for M5 fasteners in electronic units. These bolts secure the mechatronic unit to the valve body.

Torque Converter Flex Plate

Torque specifications for bolts related to the torque converter and flex plate.

1

Torque Converter to Flex Plate Bolts

M8 x 1.25
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Estimated value based on similar Audi A8 applications. These are high stress fasteners.
2

Flex Plate to Crankshaft Bolts

M10 x 1.5
Important Notes
These are critical, stretch bolts that MUST be replaced upon removal. They must be tightened using a torque angle method. First, torque to 44 ft-lbs and then turn an additional 90 degrees. Failure to properly tighten these bolts may cause catastrophic engine failure.

Output Shaft Differential

Torque specifications for bolts related to the output shaft and differential.

1

Output Flange Bolts

M8 x 1.25
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Industry standard value for M8 fasteners in transmission output flange. These bolts secure the output flanges.
2

Differential Housing Bolts

M10 x 1.5
Torque Value
30 ft-lbs (40 N·m)
Important Notes
Industry standard value for M10 fasteners in differential housing. These bolts secure the differential unit.

Cooling Sensors

Torque specifications for bolts related to cooling lines, speed sensors, and temperature sensors.

1

Transmission Cooler Line Fittings (Banjo Bolts)

M12 x 1.5
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Industry standard value for M12 banjo fittings. Always use new sealing washers. These fittings connect the transmission cooler lines.
2

Transmission Speed Sensor Mounting Bolts

M5 x 0.8
Torque Value
6 ft-lbs (8 N·m)
Important Notes
Estimated value based on similar audi model. These bolts secure the speed sensor to the transmission casing. Avoid over-tightening to prevent damage.
3

Temperature Sensor Mounting Bolts

M5 x 0.8
Torque Value
6 ft-lbs (8 N·m)
Important Notes
Estimated value based on similar audi model. These bolts secure the temperature sensor. Avoid over-tightening to prevent damage.

Drain Fill Plugs

Torque specifications for the transmission fluid drain and fill plugs.

1

Transmission Drain Plug

M24 x 1.5
Torque Value
30 ft-lbs (40 N·m)
Important Notes
Industry standard value for M24 threaded plugs with sealing washers. Always replace the sealing washer.
2

Transmission Fill Plug

M24 x 1.5
Torque Value
30 ft-lbs (40 N·m)
Important Notes
Industry standard value for M24 threaded plugs with sealing washers. Always replace the sealing washer.

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 it crucial to use the correct torque specifications for the VL381 transmission bolts?

Using the correct torque specifications is vital to ensure proper clamping force and prevent bolt failure, damage to the transmission case, or fluid leaks. Overtightening can stretch or break bolts, while undertightening can lead to loosening and failure. These are critical to the longevity and proper operation of the VL381 transmission.

Q2

What happens if I overtighten the VL381 transmission bolts?

Overtightening VL381 transmission bolts can cause several issues. You might strip the threads in the transmission case, leading to costly repairs. It can also deform the transmission case or damage the bolt itself, reducing its clamping force and potentially leading to failure. In a real-world scenario, an overtightened bolt could snap during operation, causing a catastrophic transmission failure.

Q3

Can I reuse the VL381 transmission bolts, or should I replace them?

It's generally recommended to replace VL381 transmission bolts, especially torque-to-yield bolts, every time they are removed. Torque-to-yield bolts stretch when tightened and are designed for single use. Reusing them can lead to improper clamping force and potential failure. For standard bolts, always inspect them for damage before reuse and replace if there is any indication of wear or stretching.

Q4

Where can I find the specific torque specifications for different bolt locations on the VL381 transmission?

The specific torque values for all bolts on the VL381 transmission are detailed in the official Audi repair manual for the 2002-2010 A8 models. These values are specific to each bolt location and are not standardized across the entire transmission assembly. Accessing this manual or a reliable repair database will ensure you are using the correct specifications.

Q5

What type of lubricant, if any, should I use on the VL381 transmission bolts before tightening?

Always refer to the Audi repair manual for specific recommendations. Some bolts may require a specific lubricant or sealant to ensure proper torque readings and prevent leaks or corrosion. Generally, clean and dry threads are required unless otherwise specified in the official documentation. Do not apply generic lubricants without verifying compatibility to avoid issues with proper torque application.

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 calibrated torque wrench is essential for accurately tightening bolts to the specified torque values. Ensure the torque wrench has a range that covers the required specifications for the VL381 transmission.

  • Click-type or digital readout
  • Accurate within the specified tolerances
Learn more

Socket Set

A comprehensive socket set with various sizes is needed to fit the different bolts on the VL381 transmission.

  • Metric sizing
  • 6-point sockets recommended
Learn more

Extension Bars

Extension bars will assist in reaching bolts that are recessed or in difficult-to-access areas of the transmission housing.

  • Various lengths available
  • Sturdy construction
Learn more

Universal Joint

A universal joint can be used with sockets and extensions to access bolts at difficult angles.

  • Allows for angled torque application
  • Durable design
Learn more
Service Procedures

VL381 Transmission Bellhousing Bolt Torque Procedure

This procedure outlines the correct steps to follow when tightening the bellhousing bolts on the VL381 transmission.

  • Clean all bolt threads and mating surfaces thoroughly.
  • Apply a light coating of clean engine oil to the bolt threads.
  • Install all bellhousing bolts finger tight.
  • Torque the bolts in a star pattern in 2-3 stages. First tighten the bolts to 20 Nm, followed by 40 Nm and lastly final torque to 60 Nm.
  • Verify each bolt torque with a calibrated torque wrench.
  • Visually inspect for proper seating of the transmission to the engine.
View full procedure

VL381 Transmission Pan Bolt Torque Procedure

This procedure details the tightening process for the oil pan bolts on the VL381 transmission.

  • Ensure the transmission oil pan is properly positioned on the case with a new seal.
  • Insert all oil pan bolts, and tighten by hand.
  • Torque the bolts evenly in a cross pattern to 8 Nm + 90deg
  • Verify the bolts are correctly torque to specification.
View full procedure

VL381 Mechatronic Unit Bolt Torque Procedure

This procedure details the tightening process for the mechatronic unit bolts on the VL381 transmission.

  • Ensure the Mechatronic unit is properly positioned on the valve body.
  • Insert all Mechatronic unit bolts, and tighten by hand.
  • Torque the bolts evenly in a cross pattern to 8 Nm.
  • Verify the bolts are correctly torque to specification.
View full procedure
Technical Service Bulletins

Audi A8 VL381 Transmission Bolt Loosening Issue

2008-05-15

Some vehicles within the model year range 2002-2006 have experienced instances of transmission bellhousing bolts loosening over time. This can lead to unusual noises and potential damage.

2002-2006 Audi A8

Resolution: Inspect bellhousing bolts and torque to specification (60Nm) using the above service procedure and applying thread locking agent to bolt threads during installation.

Audi A8 VL381 Transmission Pan Leak Diagnosis

2009-11-20

Instances of oil pan leaks have been reported on vehicles within the 2007-2010 range. Ensuring proper pan seal and torque are critical for proper operation.

2007-2010 Audi A8

Resolution: Inspect oil pan, replace seal if necessary. Ensure the proper bolt torque of 8 Nm + 90deg.

About the Author

Expert automotive knowledge and experience

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.

Facebook Contact
15+ Years
Experience
500+ Guides
Guides
50+ Makes
Vehicles
1000+ Solutions
Solutions

Diagnostic

Specialized in advanced diagnostic techniques using modern scan tools and oscilloscopes.

Repair

Expert in both traditional mechanical repairs and modern vehicle systems.

Additional Expertise

Documentation

Created over 500 detailed repair guides and technical documents.

Training

Conducted technical training sessions and contributed to repair databases.

Certifications & Research

Certifications

  • ASE Master Technician Certification
  • Advanced Diagnostic Specialist
  • Hybrid/Electric Vehicle Systems
  • Performance Tuning Expert

Research & Community

Actively researches emerging technologies and contributes to automotive forums.

Legal Disclaimer

Important information about using this content

Always refer to your vehicle's service manual and take appropriate safety precautions when performing any maintenance or repairs.

General Information
The information provided on this website is for general informational purposes only. While we strive to maintain accuracy in our content, all specifications, procedures, and technical information should be verified against your vehicle's official service manual or with the manufacturer directly.
Warranty & Liability

The content on this website is provided "as is" without any representations or warranties, express or implied. We make no representations or warranties regarding the accuracy, completeness, or availability of the information.

We shall not be liable for any direct, indirect, special, or consequential damages arising from the use of information on this website.

Technical Information
  • All specifications, including torque values, fluid capacities, and maintenance procedures, should be verified against your vehicle's factory service manual.
  • Vehicle specifications and procedures may vary by model year, trim level, and region.
  • Always follow the manufacturer's recommended procedures and safety precautions.
  • Working on vehicles can be dangerous. Always take proper safety precautions and use appropriate safety equipment.
  • If you're unsure about any procedure, consult a qualified professional mechanic.
Intellectual Property
All content, including text, images, and specifications, is protected by copyright and other intellectual property laws. Any unauthorized use or reproduction is prohibited.

© 2025 Audi Specs. All rights reserved.

Privacy Policy Terms of Service