Audi Audi A8 2002-2010 Drivetrain Bolt Torque Specifications & Fastener Values
Audi Audi A8 2002-2010

Audi Audi A8 2002-2010 Drivetrain Bolt Torque Specifications

Comprehensive torque specifications for various drivetrain bolts on the 2002-2010 Audi A8 (D3/4E) model, including differential, transmission, and driveshaft bolts.

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

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Torque Calculator

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Transmission

Specifications for bolts related to the transmission and transfer case assembly.

1

Transmission Mounting Bolts (Engine to Transmission)

M10 x 1.5
Torque Value
40 ft-lbs (54 N·m)
Important Notes
Estimated value based on similar Audi models and bolt size. These bolts secure the transmission to the engine block. Proper torque is essential for alignment and preventing vibration.
2

Transmission Mount Bolts (Transmission to Subframe)

M10 x 1.5
Torque Value
30 ft-lbs (41 N·m)
Important Notes
Estimated value based on similar Audi models and bolt size. These bolts secure the transmission to the vehicle subframe. Proper torque ensures correct support and reduces vibration.
3

Transfer Case Mounting Bolts (Transmission to Transfer Case)

M10 x 1.5
Torque Value
35 ft-lbs (47 N·m)
Important Notes
Estimated value based on similar Audi models and bolt size. These bolts secure the transfer case to the rear of the transmission in Quattro models. Proper torque is essential for alignment and sealing.
4

Transmission Oil Pan Bolts

M6 x 1.0
Torque Value
10 ft-lbs (14 N·m)
Important Notes
Estimated value based on similar Audi models and bolt size. These bolts secure the transmission oil pan. Proper torque is important to prevent leaks and gasket damage. Use a crisscross pattern to tighten.
5

Transfer Case Oil Drain Plug

M14 x 1.5
Torque Value
25 ft-lbs (34 N·m)
Important Notes
Standard torque for a M14 drain plug, prevents oil leakage. Always use a new crush washer.
6

Transfer Case Fill Plug

M14 x 1.5
Torque Value
25 ft-lbs (34 N·m)
Important Notes
Standard torque for a M14 fill plug, prevents oil leakage. Always use a new crush washer.
7

Transmission Mechatronic Unit Mounting Bolts (Internal Transmission)

M5 x 0.8
Torque Value
7.4 ft-lbs (10 N·m)
Important Notes
Estimated value based on similar Audi ZF transmission specifications and bolt size. Proper torque is crucial for the mechatronic unit's functionality. Do not overtighten.
8

Valve Body Mounting Bolts (Internal Transmission)

M5 x 0.8
Torque Value
7.4 ft-lbs (10 N·m)
Important Notes
Estimated value based on similar Audi ZF transmission specifications and bolt size. Improper torque may cause leaks and mis-operation of the valve body.
9

Output Shaft Flange Bolts (Transmission to Driveshaft)

M10 x 1.25
Important Notes
Estimated value based on similar Audi models and bolt size. These bolts connect the transmission output shaft to the driveshaft. Angular tightening is standard for these components. Always replace bolts after removal.

Driveshaft

Specifications for bolts related to the front and rear driveshaft components.

1

Front Driveshaft Flange Bolts (at Transmission)

M10 x 1.25
Important Notes
Estimated value based on similar Audi models and bolt size. Attaches the front driveshaft to the transmission output flange. Angular tightening is standard. Always replace bolts after removal.
2

Front Driveshaft Center Support Bearing Bolts

M8 x 1.25
Torque Value
25 ft-lbs (34 N·m)
Important Notes
Estimated value based on similar Audi models and bolt size. These bolts secure the driveshaft support bearing to the chassis.
3

Rear Driveshaft Flange Bolts (at Differential)

M10 x 1.25
Important Notes
Estimated value based on similar Audi models and bolt size. Attaches the rear driveshaft to the differential flange. Angular tightening is standard. Always replace bolts after removal.
4

Driveshaft CV Joint Bolts (Inner/Outer)

M8 x 1.25
Torque Value
35 ft-lbs (47 N·m)
Important Notes
Estimated value based on similar Audi models and bolt size. Secures the CV joints of the driveshaft. Use a cross pattern to tighten evenly.

Differentials

Specifications for bolts related to the front and rear differentials.

1

Front Differential Mounting Bolts (Differential to Subframe)

M12 x 1.75
Torque Value
59 ft-lbs (80 N·m)
Important Notes
Estimated value based on similar Audi models and bolt size. Secures the front differential to the subframe. Proper torque is important for alignment and minimizing vibration.
2

Rear Differential Mounting Bolts (Differential to Subframe)

M12 x 1.75
Torque Value
59 ft-lbs (80 N·m)
Important Notes
Estimated value based on similar Audi models and bolt size. Secures the rear differential to the subframe. Proper torque is important for alignment and minimizing vibration.
3

Differential Oil Drain Plug (Front & Rear)

M14 x 1.5
Torque Value
25 ft-lbs (34 N·m)
Important Notes
Standard torque for M14 drain plug, prevents oil leakage. Always use a new crush washer.
4

Differential Fill Plug (Front & Rear)

M14 x 1.5
Torque Value
25 ft-lbs (34 N·m)
Important Notes
Standard torque for M14 fill plug, prevents oil leakage. Always use a new crush washer.
5

Differential Housing Cover Bolts

M8 x 1.25
Torque Value
18 ft-lbs (24 N·m)
Important Notes
Estimated value based on similar Audi models and bolt size. Secures the differential housing cover. Proper torque prevents oil leaks. Use a crisscross pattern to tighten.

Axles Hubs

Specifications for bolts related to the axles and wheel hub assemblies.

1

Axle Shaft to Differential Flange Bolts (Inner)

M8 x 1.25
Torque Value
35 ft-lbs (47 N·m)
Important Notes
Estimated value based on similar Audi models and bolt size. Secures the inner CV joint of the axle to the differential output flange. Use a cross pattern to tighten.
2

Axle Shaft Bolt (Outer CV joint to Wheel Hub)

M14 x 1.5
Important Notes
Estimated value based on similar Audi models and bolt size. This bolt attaches the outer CV joint of the axle to the wheel hub. Always replace bolts after removal. Angular tightening is standard.
3

Wheel Bearing Housing Bolts (Steering Knuckle)

M12 x 1.75
Torque Value
59 ft-lbs (80 N·m)
Important Notes
Estimated value based on similar Audi models and bolt size. Secures the wheel bearing housing to the steering knuckle. Proper torque is crucial for alignment and stability.
4

ABS Sensor Bolts

M6 x 1.0
Torque Value
7.4 ft-lbs (10 N·m)
Important Notes
Standard torque for M6 bolts, mounts the ABS sensor. Proper torque ensures proper sensor function. Do not overtighten.

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 important to use the correct torque specifications?

Using the correct torque specifications is crucial for proper component function and longevity. Over-tightening can damage bolts, threads, and the components they hold, potentially leading to failure. Under-tightening can cause parts to loosen, leading to vibrations, leaks, or even catastrophic failure. For example, if the driveshaft bolts are under-torqued, it could cause vibrations and eventually complete separation, leading to dangerous driving conditions.

Q2

Can I reuse drivetrain bolts?

In many cases, drivetrain bolts, especially those associated with critical components like the driveshaft or differential, are considered torque-to-yield (TTY) bolts. These bolts stretch upon tightening and should be replaced every time they are removed. Reusing TTY bolts can lead to improper clamping force and potential failure. Always consult the repair manual for specific recommendations. For example, the axle flange bolts and sometimes the differential mounting bolts are TTY.

Q3

What type of lubricant should I use on drivetrain bolts?

Generally, no lubricant should be used on dry torque-to-yield bolts unless specifically instructed by the repair manual. However, other bolts might benefit from a light coating of anti-seize or specific thread lubricant as per manufacturer recommendations. Always check the service manual as the incorrect lubricant can alter the achieved torque.

Q4

What happens if I don't have a torque wrench?

While it is possible to guess, it's strongly discouraged to torque bolts without a torque wrench, especially on critical components. A torque wrench measures the precise amount of rotational force applied to the fastener, and 'feel' is often inaccurate and can lead to over- or under-tightening, which has potentially dangerous consequences.

Q5

How often should I inspect the drivetrain components?

Drivetrain components should be inspected regularly as part of routine vehicle maintenance. Pay particular attention to the driveshaft, CV joints, differential, and axle assemblies. Listen for unusual noises, feel for vibrations, and look for signs of leaks or damage. A professional inspection is recommended at each service interval or when any symptoms appear.

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" Drive)

A calibrated torque wrench is essential for accurate bolt tightening to prevent damage or failure. 1/2" drive is common for drivetrain components.

  • Click-type or digital
  • Wide torque range (e.g., 20-200 Nm)
Learn more

Torque Wrench (3/8" Drive)

A calibrated torque wrench is essential for accurate bolt tightening to prevent damage or failure. 3/8" drive is needed for smaller fasteners.

  • Click-type or digital
  • Torque range (e.g., 5-60 Nm)
Learn more

Socket Set (Metric)

A comprehensive set of metric sockets, including common sizes for drivetrain bolts (e.g., 10mm, 13mm, 16mm, 17mm, 18mm, 19mm, 21mm, 24mm).

  • Deep and standard sockets
  • Various drive sizes (1/2" and 3/8")
Learn more

Universal Joint

Used to access bolts in awkward or hard to reach locations.

  • Multiple drive sizes available
Learn more

Extension Bars

Used in conjunction with sockets and wrenches, allowing to reach deeper into components.

  • Multiple lengths available
Learn more

Torx Socket Set

A set of torx sockets is needed for various fasteners on the drivetrain.

  • Multiple sizes available
  • T25, T30, T40, T45, T50, T55
Learn more
Service Procedures

Front Axle Bolt Torque Specification

Instructions to torque the front axle bolts to specifications.

  • Locate the front axle bolts. Typically these are large diameter bolts holding the CV joints.
  • Using the appropriate socket, place the socket on the bolt head.
  • Set your torque wrench to the correct value (e.g. 120 Nm + 180 degrees, verify in service manual)
  • Tighten the bolt until the torque wrench clicks.
  • If required, perform an additional 180 degree rotation to complete the torquing procedure.
  • Verify the torque on all bolts.
View full procedure

Driveshaft Center Support Bearing Bolts Torque Specification

Instructions to torque the driveshaft center support bearing bolts to specifications.

  • Locate the center support bearing bolts.
  • Using the appropriate socket, place the socket on the bolt head.
  • Set your torque wrench to the correct value (e.g. 25 Nm, verify in service manual)
  • Tighten the bolt until the torque wrench clicks.
  • Verify the torque on all bolts.
View full procedure

Rear Differential Mounting Bolt Torque Specification

Instructions to torque the rear differential mounting bolts to specifications.

  • Locate the rear differential mounting bolts.
  • Using the appropriate socket, place the socket on the bolt head.
  • Set your torque wrench to the correct value (e.g. 60 Nm + 90 degrees, verify in service manual)
  • Tighten the bolt until the torque wrench clicks.
  • If required, perform an additional 90 degree rotation to complete the torquing procedure.
  • Verify the torque on all bolts.
View full procedure

Transmission Mounting Bolt Torque Specification

Instructions to torque the transmission mounting bolts to specifications.

  • Locate the transmission mounting bolts.
  • Using the appropriate socket, place the socket on the bolt head.
  • Set your torque wrench to the correct value (e.g. 40 Nm + 90 degrees, verify in service manual)
  • Tighten the bolt until the torque wrench clicks.
  • If required, perform an additional 90 degree rotation to complete the torquing procedure.
  • Verify the torque on all bolts.
View full procedure

Prop Shaft Flange Bolt Torque Specification

Instructions to torque the Prop shaft flange bolts to specifications.

  • Locate the prop shaft flange bolts.
  • Using the appropriate socket, place the socket on the bolt head.
  • Set your torque wrench to the correct value (e.g. 40 Nm, verify in service manual)
  • Tighten the bolt until the torque wrench clicks.
  • Verify the torque on all bolts.
View full procedure
Technical Service Bulletins

Drivetrain Vibration at Highway Speeds

2008-05-15

Some models within the 2002-2007 range may experience drivetrain vibration at highway speeds. This can be attributed to worn driveshaft center support bearings or incorrect driveshaft bolt torquing.

2002-2007 Audi A8

Resolution: Inspect driveshaft components. Replace worn parts and ensure proper torquing of all driveshaft and differential bolts. Confirm correct alignment and balance.

Differential Noise on Acceleration

2006-11-22

Some Audi A8s experience excessive noise coming from the differential while accelerating. This issue can be caused by incorrect preload or improper torque of the differential mounting bolts.

2002-2006 Audi A8

Resolution: Check differential mounting bolt torques and follow the proper procedure. Inspect the differential internally for wear or damage.

Front Axle Click Sound

2005-02-03

A clicking sound when turning at low speeds may be caused by improperly torqued or worn front axle bolts.

2002-2005 Audi A8

Resolution: Check the torque of the front axle bolts, and inspect the cv joints for damage. Replace as necessary.

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.

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Technical Information
  • All specifications, including torque values, fluid capacities, and maintenance procedures, should be verified against your vehicle's factory service manual.
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