Audi Audi S4 2003-2008 Drivetrain Bolt Torque Specifications & Fastener Values
Audi Audi S4 2003-2008

Audi Audi S4 2003-2008 Drivetrain Bolt Torque Specifications

Comprehensive list of drivetrain bolt torque specifications for the 2003-2008 Audi S4 (B6 and B7 generations). Includes values for transmission, differential, driveshaft, and axle components.

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

Manual Transmission

Torque specifications for the 6-speed manual transmission components of a 2003-2008 Audi S4. Ensure all torque values are accurately applied to prevent component failure and ensure proper operation.

1

Transmission Housing Bolts

M10 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Secures the two main transmission case halves. Ensure even tightening to prevent leaks. Based on similar Audi models.
2

Transmission Mount Bolts (to Transmission)

M12 x 1.75
Torque Value
30 ft-lbs (40 N·m)
Important Notes
Attaches the transmission to the mounts. Estimated based on bolt size and application.
3

Transmission Mount Bolts (to Chassis)

M12 x 1.75
Important Notes
Secures the transmission mounts to the chassis. Final tightening includes an angle step. Based on similar Audi models.
4

Clutch Pressure Plate Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Secures the pressure plate to the flywheel. Use a star pattern to ensure even clamping pressure. Industry Standard torque value.
5

Flywheel Bolts

M10 x 1.5
Important Notes
Fastens the flywheel to the crankshaft. Always use new bolts, this is a stretch bolt. Based on similar Audi models.
6

Slave Cylinder Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Secures the slave cylinder to the bell housing. Estimated based on bolt size and application.
7

Shift Linkage Bolts

M8 x 1.25
Torque Value
15 ft-lbs (20 N·m)
Important Notes
Connects the shift linkage to the transmission. Estimated based on bolt size and application.
8

Driveshaft Flange Bolts (to Transmission)

M10 x 1.5
Torque Value
30 ft-lbs (40 N·m)
Important Notes
Secures the driveshaft to the transmission output flange. Based on similar Audi models.
9

Drain Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the transmission case at the drain point. Industry Standard.

Automatic Transmission

Torque specifications for the ZF 6HP19 automatic transmission used in the 2003-2008 Audi S4. Adhere to the specified torque values to ensure proper sealing and prevent component damage.

1

Transmission Pan Bolts

M6 x 1
Torque Value
7 ft-lbs (10 N·m)
Important Notes
Secures the transmission oil pan to the housing. Low torque to prevent damage. Based on similar Audi models.
2

Mechatronic Unit Mounting Bolts

M6 x 1
Torque Value
7 ft-lbs (10 N·m)
Important Notes
Secures the mechatronic unit within the transmission. Based on similar Audi models.
3

Transmission Mount Bolts (to Transmission)

M12 x 1.75
Torque Value
30 ft-lbs (40 N·m)
Important Notes
Attaches the transmission to the mounts. Estimated based on bolt size and application.
4

Transmission Mount Bolts (to Chassis)

M12 x 1.75
Important Notes
Secures the transmission mounts to the chassis. Final tightening includes an angle step. Based on similar Audi models.
5

Driveshaft Flange Bolts (to Transmission)

M10 x 1.5
Torque Value
30 ft-lbs (40 N·m)
Important Notes
Secures the driveshaft to the transmission output flange. Based on similar Audi models.
6

Torque Converter Bolts

M10 x 1.5
Important Notes
Fastens the torque converter to the flexplate. Use new bolts for this critical application. Based on similar Audi models.
7

Drain Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the transmission case at the drain point. Industry Standard.
8

Filler Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Secures the fill port. Industry Standard.

Driveshaft

Torque specifications for the driveshaft components of the 2003-2008 Audi S4. Proper torque is essential for driveline stability and performance.

1

Driveshaft Center Support Bearing Bolts

M8 x 1.25
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Secures the center support bearing to the chassis. Based on similar Audi models.
2

Driveshaft CV Joint Bolts (to differential)

M10 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
Fastens CV joints to differential flanges. Based on similar Audi models.
3

Driveshaft Flange Bolts (to transmission)

M10 x 1.5
Torque Value
30 ft-lbs (40 N·m)
Important Notes
Secures the driveshaft to the transmission output flange. Based on similar Audi models.

Front Differential

Torque specifications for the front differential components of the 2003-2008 Audi S4. Ensure proper mounting and sealing to maintain differential performance.

1

Differential Mounting Bolts (to subframe)

M12 x 1.75
Important Notes
Fastens the differential to the subframe. Final tightening includes an angle step. Based on similar Audi models.
2

Differential Cover Bolts

M8 x 1.25
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Secures the differential cover to the housing. Estimated based on bolt size and application.
3

Driveshaft Flange Bolts (to Differential)

M10 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
Fastens the front driveshafts to the differential flange. Based on similar Audi models.
4

Drain Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the differential case at the drain point. Industry Standard.
5

Filler Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Secures the fill port. Industry Standard.

Rear Differential

Torque specifications for the rear differential components of the 2003-2008 Audi S4. Proper mounting and sealing are essential for optimal performance and longevity.

1

Differential Mounting Bolts (to subframe)

M12 x 1.75
Important Notes
Secures the rear differential to the subframe. Final tightening includes an angle step. Based on similar Audi models.
2

Differential Cover Bolts

M8 x 1.25
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Secures the rear differential cover. Estimated based on bolt size and application.
3

Driveshaft Flange Bolts (to Differential)

M10 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
Connects the driveshaft to the differential. Based on similar Audi models.
4

Axle Flange Bolts (to Differential)

M10 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
Attaches the axles to the differential output flanges. Based on similar Audi models.
5

Drain Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the differential case at the drain point. Industry Standard.
6

Filler Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Secures the fill port. Industry Standard.

Axles Cv Joints

Torque specifications for axle and CV joint components of the 2003-2008 Audi S4. Correct torquing is crucial for safety and preventing driveline issues.

1

Axle Nut (Front and Rear)

M24 x 1.5
Important Notes
Secures the axle to the wheel hub. Always use a new nut. Based on similar Audi models.
2

CV Joint Bolts (to driveshaft/flange)

M10 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
Connects CV joints to their flanges/driveshafts. Based on similar Audi models.

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 crucial for drivetrain bolts?

Using the correct torque specification ensures proper clamping force, preventing bolts from loosening due to vibration or stress. Over-tightening can lead to bolt stretching, thread damage, or component failure. Under-tightening can cause components to shift, leading to premature wear, damage, and potential safety hazards. For example, a loosely torqued driveshaft bolt could lead to vibration, damage to the CV joint, or even a complete driveline separation at speed.

Q2

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

While it's highly recommended to use a torque wrench for drivetrain components, if you do not have one, a proper torque can be estimated to be 'firmly hand tight'. This is not the preferred method, and should only be used in an emergency. Without a calibrated wrench, it is impossible to accurately gauge the correct amount of torque being applied to a bolt. Without the proper calibration, damage is likely. For example, not having a properly torqued rear differential bolt could lead to premature differential failure, or possibly damage to the chassis mounting points. Always use a torque wrench!

Q3

Should I use new bolts when working on the drivetrain?

It's highly recommended to use new bolts, especially for critical drivetrain components, as many are torque-to-yield (TTY) bolts designed for single use. These bolts stretch slightly when tightened to the specified torque and become unreliable if reused. Replacing them ensures correct clamping force and prevents failure. For example, reusing a driveshaft bolt may mean it doesn't hold at the designed torque, leading to driveline failure. Always replace TTY bolts.

Q4

What is the difference between Nm and lb-ft torque specifications?

Nm (Newton-meters) and lb-ft (pound-feet) are different units for measuring torque. Nm is the metric unit and is more commonly used in Europe, whereas lb-ft is the imperial unit, which is often used in the USA. Make sure your torque wrench is calibrated to the specifications listed for your fasteners. There are online conversion tools available to help you go between these units, if you need. Always double check the units before using your torque wrench!

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 accurately tightening bolts to specified torque values. A 1/2 inch drive is common for the size of bolts used on this drivetrain.

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

Torque Wrench (3/8 inch drive)

A smaller torque wrench, with a 3/8 inch drive, is useful for lower torque values.

  • Lower torque range (e.g., 5-50 Nm)
  • Click-type or digital display
  • Calibrated for accuracy
Learn more

Socket Set (Metric)

A comprehensive set of metric sockets, including standard and deep sockets, in 1/2 inch and 3/8 inch drives is necessary to fit the range of bolt heads.

  • Sizes ranging from 8mm to 24mm
  • 6-point and 12-point options
  • Chrome vanadium steel construction
Learn more

Hex/Allen Key Set (Metric)

A set of hex or allen keys, also metric, is necessary for bolts that do not have external heads.

  • Sizes from 3mm to 10mm
  • L-shaped or T-handle options
  • Hardened steel
Learn more

Torx Socket Set (Metric)

Torx sockets, both external and internal, are used for several drivetrain fasteners.

  • Sizes from T20 to T60
  • E-Torx sockets also required
  • Hardened steel
Learn more

Penetrating Oil

Useful for loosening stubborn or corroded bolts prior to removal.

  • Fast-acting
  • Corrosion inhibitor
Learn more
Service Procedures

Front Axle Drive Shaft Bolt Tightening

Procedure for tightening the bolts that secure the front axle drive shafts to the transmission and wheel hub.

  • Locate the drive shaft bolts at the transmission flange and wheel hub.
  • Clean the bolts and mating surfaces to remove any dirt or debris.
  • Apply a light coating of anti-seize compound to the bolt threads if desired (not typically required).
  • Tighten bolts to the manufacturer's specified torque in a star pattern (see spec below) in two stages if required.
  • Verify the torque with the torque wrench.
View full procedure

Rear Differential Bolt Tightening

Procedure for tightening the bolts securing the rear differential to the chassis and axles.

  • Locate the bolts securing the rear differential to the subframe or chassis.
  • Clean the bolts and mating surfaces.
  • Apply anti-seize if desired (typically not required).
  • Tighten the bolts using a crisscross pattern to the specified torque.
  • Verify torque with the torque wrench.
View full procedure

Transmission Mount Bolt Tightening

Procedure for tightening the bolts attaching the transmission mounts to the transmission and chassis.

  • Locate the bolts that secure the transmission mounts to the transmission and body or subframe.
  • Clean bolts and mounting locations.
  • Install the mount and install fasteners finger tight.
  • Tighten the bolts to the specified torque, typically in multiple stages with a final torque stage.
  • Verify torque.
View full procedure

Prop Shaft Bolt Tightening

Procedure for tightening the bolts connecting the prop shaft to the transmission and rear differential.

  • Locate the prop shaft bolts at the transmission and rear differential flanges.
  • Clean mating surfaces and fasteners.
  • Install fasteners finger tight.
  • Tighten bolts to the manufacturer's specified torque, usually in a cross pattern to ensure even tightening.
  • Verify the torque with the torque wrench.
View full procedure
Technical Service Bulletins

Prop Shaft Bolt Loosening Issues

2006-05-15

Some 2003-2005 Audi S4 models have exhibited issues with prop shaft bolts loosening over time. This can result in noise and vibration.

2003-2005

Resolution: Inspect the prop shaft bolts for proper torque and condition. Apply new bolts and tighten to the manufacturer-specified torque of 60Nm + 90 degrees. A thread-locking compound can be used as a preventative measure. Check after 1000 miles.

Rear Differential Mounting Bolt Corrosion

2007-11-20

Reports of corrosion on rear differential mounting bolts causing difficult removal have been noted, particularly in vehicles exposed to harsh weather conditions.

2003-2008

Resolution: Inspect the bolts for corrosion. Replace any corroded bolts. Apply a light coat of anti-seize to all differential bolts upon reinstallation. Torque the bolts to 100Nm + 90 degrees.

Front Axle Bolt Stretch

2004-08-10

Front axle bolts should be checked for stretch and replaced when removing. Reusing them can result in failure and potential damage.

2003-2004

Resolution: Always replace front axle bolts when removing, torque to 70Nm + 90 degrees. Bolts are single use.

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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