Audi Audi S4 2016-present Drivetrain Bolt Torque Specifications & Fastener Values
Audi Audi S4 2016-present

Audi Audi S4 2016-present Drivetrain Bolt Torque Specifications

Comprehensive torque specifications for various drivetrain bolts on the 2016-Present Audi S4 (B9 and B9.5 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

Transmission

Torque specifications for components related to the transmission or gearbox. This includes mounting bolts, plugs, and internal components.

1

Transmission Housing Bolts (to engine)

M10 x 1.5
Torque Value
35 ft-lbs (47 N·m)
Important Notes
Secures the transmission to the engine block. Critical for alignment and preventing leaks. Estimated value based on similar applications.
2

Transmission Mount Bolts (to chassis)

M12 x 1.75
Important Notes
Fastens the transmission mount to the chassis. Torque plus angle ensures correct mount compression.
3

Transmission Fill Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the transmission fill port. Use a new crush washer. Estimated value.
4

Transmission Drain Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the transmission drain port. Use a new crush washer. Estimated value.
5

Mechatronic Unit Bolts (within transmission)

M6 x 1.0
Torque Value
6 in-lbs (8 N·m)
Important Notes
Secures the mechatronic unit within the transmission. Low torque to prevent damage. Estimated value.
6

Dual Clutch Pack Bolts

M10 x 1.5
Important Notes
Secures the dual clutch assembly. Torque plus angle ensures correct clamping force.
7

Valve Body Bolts (within transmission)

M6 x 1.0
Torque Value
7.4 in-lbs (10 N·m)
Important Notes
Secures the valve body within the transmission. Proper torque is critical for operation. Estimated value.

Front Differential

Torque specifications for the front differential components, including housing, mounts, and plugs.

1

Differential Housing Bolts (to transmission/engine)

M10 x 1.5
Torque Value
40 ft-lbs (54 N·m)
Important Notes
Secures the front differential to the transmission/engine. Critical for structural integrity. Estimated value.
2

Differential Mount Bolts (to subframe)

M12 x 1.75
Important Notes
Fastens the front differential mount to the subframe. Torque plus angle ensures secure mounting.
3

Differential Fill Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the differential fill port. Use a new crush washer. Estimated value.
4

Differential Drain Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the differential drain port. Use a new crush washer. Estimated value.

Rear Differential

Torque specifications for components of the rear differential, including housing, mounts, cover, and plugs.

1

Differential Housing Bolts (to subframe)

M10 x 1.5
Torque Value
40 ft-lbs (54 N·m)
Important Notes
Secures the rear differential to the subframe. Critical for driveline integrity. Estimated value.
2

Differential Mount Bolts (to subframe)

M12 x 1.75
Important Notes
Secures the rear differential mount to the subframe. Torque plus angle ensures proper compression and mounting.
3

Differential Cover Bolts

M8 x 1.25
Torque Value
20 ft-lbs (27 N·m)
Important Notes
Secures the differential cover and prevents fluid leaks. Estimated value.
4

Differential Fill Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the differential fill port. Use a new crush washer. Estimated value.
5

Differential Drain Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the differential drain port. Use a new crush washer. Estimated value.

Driveshaft

Torque specifications for components related to the driveshaft, including center support bearing and flange bolts.

1

Driveshaft Center Support Bearing Bolts (to chassis)

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Fastens the driveshaft support bearing to the chassis. Estimated value.
2

Driveshaft Flange Bolts (to transmission/differential)

M10 x 1.5
Torque Value
35 ft-lbs (47 N·m)
Important Notes
Connects the driveshaft to the transmission and differentials. Ensures proper power transfer. Estimated value.
3

Driveshaft Bolts (between sections)

M10 x 1.5
Torque Value
35 ft-lbs (47 N·m)
Important Notes
Secures the two halves of a multi-part drive shaft. Estimated value.

Axles

Torque specifications for axle components, including flange bolts and CV joint boot clamps.

1

Axle Flange Bolt (to wheel hub)

M10 x 1.5
Torque Value
52 ft-lbs (70 N·m)
Important Notes
Fastens the axle to the wheel hub. Estimated value.
2

Axle Shaft Bolt (Transmission Side)

M10 x 1.5
Important Notes
Fastens the axle to the transmission. Torque plus angle ensures proper mounting. Estimated value.
3

CV Joint Boot Clamp

N/A
Torque Value
0 ft-lbs (0 N·m)
Important Notes
Proper crimping method is needed (not a torque value).

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?

Using incorrect torque can lead to several problems. Under-torquing can cause fasteners to loosen over time, leading to component failure or vibration. Over-torquing can stretch or break bolts, damage threads in housings, or distort mating surfaces, potentially causing leaks or catastrophic failure of drivetrain components. In the case of the S4's drivetrain, the high power output means this is even more important.

Q2

Should I use new bolts every time I work on the drivetrain?

While not always mandatory for every bolt, it's highly recommended for critical drivetrain components such as the driveshaft, transmission mounting bolts, and differential bolts. These are often 'torque-to-yield' bolts that stretch slightly when torqued. Reusing them can result in unreliable clamping forces and increase the risk of failure. For example, if replacing your front differential, it’s best to get all new mounting bolts.

Q3

What should I do if a bolt doesn't tighten properly at the correct torque spec?

If a bolt feels like it's stripping or 'giving' at the specified torque, stop immediately. Attempting to force it further could lead to damaging the threads, bolt, or the component it's securing. Inspect the threads of both the bolt and the receiving hole for damage. If damaged, consider using a thread repair kit or replacing the affected component. Do not proceed until it is fixed. For example, if you find the transmission mount bolt hole in the frame is damaged after removal, a thread repair is needed before reinstallation.

Q4

Do I need any special tools to torque drivetrain bolts?

Yes, a calibrated torque wrench is essential for accurately tightening bolts to the specified torque. You might also need various sockets, extensions, and possibly universal joints to access hard-to-reach fasteners in the drivetrain. In many cases, an inch-pound and foot-pound torque wrench will be needed. For instance, the smaller bolts on the rear differential may require inch pounds of torque, while the larger axle bolts require foot pounds.

Q5

How often should I check the torque on drivetrain bolts?

It's generally recommended to check the torque on drivetrain bolts after initial installation, after a short break-in period (e.g., 50-100 miles) and then at each major service interval, or if you experience unusual noises or vibrations. If you've driven in especially harsh conditions, checking the torque sooner might be beneficial. For example, if you have been on a racetrack, inspect all drivetrain components soon after.

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 applying accurate torque to drivetrain bolts. A 1/2 inch drive is suitable for most applications on the S4 drivetrain.

  • Wide torque range (e.g., 20-150 ft-lbs)
  • Click-type mechanism for accurate torque application
  • Calibration certificate recommended
Learn more

Torque Wrench (3/8 inch drive)

A calibrated 3/8 inch drive torque wrench is useful for smaller bolts and areas with limited access. Needed for lower range torque values.

  • Lower torque range (e.g., 5-80 ft-lbs)
  • Click-type mechanism for accurate torque application
  • Calibration certificate recommended
Learn more

Various Socket Set (Metric)

A comprehensive set of metric sockets is necessary to fit various bolt head sizes on the drivetrain.

  • Includes sizes ranging from 8mm to 24mm
  • 6-point sockets are recommended to prevent rounding bolts
  • Both standard and deep sockets are useful
Learn more

Extension Bars

Extension bars are essential for accessing recessed or hard-to-reach bolts within the drivetrain assembly.

  • Various lengths (3, 6, 10 inches)
  • Durable construction
  • 1/2 and 3/8 inch drive
Learn more

U-Joint/Swivel Socket

A U-joint or swivel socket allows for torque application at angles, necessary for certain drivetrain fasteners.

  • 1/2 and 3/8 inch drive options
  • Durable construction
  • Allows for off-angle access
Learn more
Service Procedures

Front Axle Bolt Torque Procedure

This procedure outlines the steps to correctly torque the front axle bolts on the Audi S4.

  • Locate the axle bolt.
  • Using the correct sized socket, place it on the bolt.
  • Set the torque wrench to the specified value (e.g., 70 Nm + 90 degrees).
  • Tighten the bolt until the torque wrench clicks.
  • If an angle is specified, proceed with the angle torque procedure.
  • Verify the final torque value.
View full procedure

Driveshaft Center Support Bearing Bolt Torque Procedure

This procedure outlines the steps to correctly torque the center support bearing bolts on the Audi S4.

  • Locate the center support bearing bolts.
  • Using the correct sized socket, place it on the bolt.
  • Set the torque wrench to the specified value (e.g., 40 Nm).
  • Tighten the bolts in a criss-cross pattern until the torque wrench clicks.
  • Verify the final torque value.
View full procedure

Rear Differential Mount Bolt Torque Procedure

This procedure outlines the steps to correctly torque the rear differential mount bolts on the Audi S4.

  • Locate the rear differential mount bolts.
  • Using the correct sized socket, place it on the bolt.
  • Set the torque wrench to the specified value (e.g., 60 Nm + 90 degrees).
  • Tighten the bolts until the torque wrench clicks.
  • If an angle is specified, proceed with the angle torque procedure.
  • Verify the final torque value.
View full procedure

Transmission Mount Bolt Torque Procedure

This procedure outlines the steps to correctly torque the transmission mount bolts on the Audi S4.

  • Locate the transmission mount bolts.
  • Using the correct sized socket, place it on the bolt.
  • Set the torque wrench to the specified value (e.g., 50 Nm).
  • Tighten the bolts until the torque wrench clicks.
  • Verify the final torque value.
View full procedure
Technical Service Bulletins

Driveshaft Bolt Loosening Issue

2018-05-15

Some 2017-2018 S4 models have reported issues with driveshaft bolt loosening. This bulletin provides updated torque specifications and application procedure.

2017-2018

Resolution: Apply updated torque specification (e.g., 50 Nm + 180 degrees) with fresh hardware. Ensure bolts are correctly prepped. Follow the service procedure and use new bolts.

Rear Differential Mounting Bolt Update

2020-09-20

This bulletin addresses a reported issue with rear differential mount bolt stretch/failure and provides updated torque specification

2016-2020

Resolution: Replace rear differential bolts with updated revision. Apply updated torque specification (e.g., 75 Nm + 90 degrees) with fresh hardware and thread locker. Follow updated tightening procedure from ELSAwin

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