Audi Audi S8 2012-2018 Drivetrain Bolt Torque Specifications
Comprehensive list of drivetrain bolt torque specifications for the 2012-2018 Audi S8 (D4) model, including transmission, differential, and axle components.
Important Information
Safety guidelines and reference information for proper torque application
Safety First
- Always verify torque specifications with your vehicle's factory service manual
- Use properly calibrated torque wrenches
- Replace all torque-to-yield (TTY) bolts - they are single-use only
- When in doubt, consult a professional mechanic
Quick Reference Guide
Quick Reference Guide
Common Torque Patterns
Star Pattern
Used for wheels and other circular bolt patterns
Cross Pattern
Used for gaskets and cover plates
Sequential Pattern
Used for head bolts and other critical components
Common Mistakes to Avoid
Common Mistakes to Avoid
Over-tightening
Exceeding the specified torque value can stretch or break fasteners, damage threads, or crack components.
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.
Follow the manufacturer's specified torque sequence pattern.
Dirty Threads
Dirt, rust, or old thread locker can affect torque readings and proper fastener tension.
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.
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.
Check if specs are for dry or lubricated threads. Use specified lubricant when required.
Recommended Tools
Recommended Tools
Torque Wrench (1/4" Drive)
Torque Wrench (3/8" Drive)
Torque Wrench (1/2" Drive)
Angle Gauge
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
This section covers torque specifications for the transmission assembly, including mounting, pan, and fluid-related components. These specs are based on common ZF transmissions used in Audi vehicles of this era.
1 Transmission Mounting Bolts to Body/Subframe
M12 x 1.5
Transmission Mounting Bolts to Body/Subframe
M12 x 1.5Torque Value
Important Notes
2 Transmission Pan Bolts
M8 x 1.25
Transmission Pan Bolts
M8 x 1.25Torque Value
Important Notes
3 Transmission Fluid Drain Plug
M14 x 1.5
Transmission Fluid Drain Plug
M14 x 1.5Torque Value
Important Notes
4 Transmission Fluid Fill Plug
M14 x 1.5
Transmission Fluid Fill Plug
M14 x 1.5Torque Value
Important Notes
5 Torque Converter Bolts to Flexplate/Driveplate
M8 x 1.25
Torque Converter Bolts to Flexplate/Driveplate
M8 x 1.25Important Notes
6 Transmission Output Flange Bolts/Nuts
M10 x 1.5
Transmission Output Flange Bolts/Nuts
M10 x 1.5Torque Value
Important Notes
Driveshaft
This section includes torque specifications for the driveshaft, including center support bearings and CV joint bolts.
1 Driveshaft Center Support Bearing Bolts
M8 x 1.25
Driveshaft Center Support Bearing Bolts
M8 x 1.25Torque Value
Important Notes
2 Front Driveshaft CV Joint Bolts/Flange Bolts to Transmission
M10 x 1.5
Front Driveshaft CV Joint Bolts/Flange Bolts to Transmission
M10 x 1.5Torque Value
Important Notes
3 Front Driveshaft CV Joint Bolts/Flange Bolts to Front Differential
M10 x 1.5
Front Driveshaft CV Joint Bolts/Flange Bolts to Front Differential
M10 x 1.5Torque Value
Important Notes
4 Rear Driveshaft CV Joint Bolts/Flange Bolts to Rear Differential
M12 x 1.5
Rear Driveshaft CV Joint Bolts/Flange Bolts to Rear Differential
M12 x 1.5Torque Value
Important Notes
Front Differential
This section details torque specifications for the front differential, including mounting and cover bolts.
1 Front Differential Mounting Bolts to Subframe
M12 x 1.75
Front Differential Mounting Bolts to Subframe
M12 x 1.75Torque Value
Important Notes
2 Front Differential Side Cover Bolts/Drain/Fill Plugs
M10 x 1.5
Front Differential Side Cover Bolts/Drain/Fill Plugs
M10 x 1.5Torque Value
Important Notes
Rear Differential
This section details torque specifications for the rear differential, including mounting and cover bolts.
1 Rear Differential Mounting Bolts to Subframe
M14 x 2.0
Rear Differential Mounting Bolts to Subframe
M14 x 2.0Torque Value
Important Notes
2 Rear Differential Cover Bolts/Drain/Fill Plugs
M10 x 1.5
Rear Differential Cover Bolts/Drain/Fill Plugs
M10 x 1.5Torque Value
Important Notes
Axles
This section covers torque specifications for axle components, including the axle shaft nut and CV joint bolts.
1 Axle Shaft Nut (Hub Nut)
M24 x 1.5
Axle Shaft Nut (Hub Nut)
M24 x 1.5Important Notes
2 Axle Inner CV Joint Bolts to Differential
M10 x 1.5
Axle Inner CV Joint Bolts to Differential
M10 x 1.5Torque Value
Important Notes
Wheel Hub
This section includes torque specifications for the wheel bearing housing and related components.
1 Wheel Bearing Housing/Carrier Bolts
M14 x 1.5
Wheel Bearing Housing/Carrier Bolts
M14 x 1.5Important Notes
Troubleshooting Guide
Common issues, diagnostic steps, and prevention guidelines
Common Issues
Bolt stretching, stripped threads, uneven torque patterns
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
Diagnostic Steps
Visual inspection, torque verification, thread assessment
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
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
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
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 are torque specifications important for drivetrain bolts?
Why are torque specifications important for drivetrain bolts?
Proper torque ensures the bolts are tightened enough to prevent loosening under stress and vibration, but not so much as to cause damage like stretching, stripping threads, or component failure. Incorrect torque can lead to drivetrain malfunctions, premature wear, and even safety hazards. For example, an improperly torqued driveshaft bolt could loosen, leading to drivetrain noise, vibration, and potential failure.
Q2 What happens if I overtighten a drivetrain bolt?
What happens if I overtighten a drivetrain bolt?
Overtightening can stretch or weaken the bolt, damage the threads in the receiving component (e.g., transmission housing), or crush the gasket or sealing surfaces. This can lead to leaks, component failure, or the need for costly repairs. An overtightened differential mounting bolt might crack the mounting bracket.
Q3 What happens if I undertighten a drivetrain bolt?
What happens if I undertighten a drivetrain bolt?
Undertightening can allow the bolt to loosen over time due to vibration, leading to component movement, noise, and eventual failure. A loose transmission mount bolt, for instance, can cause clunking sounds and excessive movement, which can damage other components.
Q4 Do I need to use new bolts when reassembling drivetrain components?
Do I need to use new bolts when reassembling drivetrain components?
It's generally recommended to replace torque-to-yield (TTY) bolts and stretch bolts. These bolts are designed to stretch when tightened and should not be reused. Refer to the Audi service manual for your specific model to identify TTY bolts and other recommended bolt replacement criteria. For instance, driveshaft flange bolts often need to be replaced.
Q5 What tools are recommended for torquing drivetrain bolts?
What tools are recommended for torquing drivetrain bolts?
A calibrated torque wrench is essential for accurately applying torque. You may need a combination of sockets, extensions, and universal joints to access all the bolts. For example, a torque wrench with a low profile is useful for accessing bolts in tight engine bay locations. Ensure the torque wrench is within its calibration range for the specified torque.
Environmental Considerations
Temperature, humidity, and seasonal effects on torque specifications
Temperature Effects
Includes: High Heat, Cold Weather, Thermal Cycling
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
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
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 1/2" drive torque wrench capable of accurately measuring torque within the range required for drivetrain bolts.
- Adjustable torque settings
- Click-type mechanism for accurate torque application
- Clear scale for easy reading
Torque Wrench (3/8" Drive)
A 3/8" drive torque wrench for smaller bolts and applications with limited clearance.
- Adjustable torque settings
- Click-type mechanism for accurate torque application
- Clear scale for easy reading
Socket Set (Metric)
A comprehensive set of metric sockets in 1/2" and 3/8" drive sizes, including common sizes for drivetrain components.
- Durable construction
- Variety of sizes for different bolts
- Clear size markings
Extension Bars
Various length extension bars to reach recessed or hard to access bolts.
- Various Lengths
- Secure connection to sockets
- Durable construction
Universal Joint
Universal joints allow for angular torque application.
- Swivels in multiple directions
- Durable construction
- Secure connection to sockets
Service Procedures
Front Axle Bolt Torque Procedure
Procedure for torquing the bolts on the front axle assembly. Includes critical torque specs for CV joint and axle shaft bolts.
- Identify all required front axle bolts.
- Apply initial torque to bolts in a star pattern using 30% of specified value.
- Apply final torque to bolts in a star pattern.
- Verify torque using a calibrated torque wrench.
- Inspect bolts and connections for proper engagement.
Rear Differential Bolt Torque Procedure
Procedure for torquing the bolts on the rear differential assembly. Includes specs for mounting and fill/drain plugs.
- Identify all rear differential mounting bolts.
- Apply initial torque to bolts in a star pattern using 30% of specified value.
- Apply final torque to bolts in a star pattern according to spec.
- Torque differential fill and drain plugs to specified value.
- Verify all torque values using a calibrated torque wrench.
Driveshaft Bolt Torque Procedure
Procedure for torquing the driveshaft mounting bolts.
- Identify all driveshaft mounting bolts.
- Apply initial torque to bolts in a star pattern using 30% of specified value.
- Apply final torque to bolts in a star pattern according to spec.
- Verify all torque values using a calibrated torque wrench.
- Inspect driveshaft alignment after bolt installation.
Technical Service Bulletins
Excessive Driveshaft Vibration at High Speeds
2015-06-15Some 2012-2015 Audi S8 models may experience excessive driveshaft vibration at high speeds. This may be related to improper driveshaft bolt torque or driveline component wear.
Resolution: Inspect driveshaft, center bearing and differential mounts for play or damage. Verify proper torque specification on driveshaft bolts and replace any faulty or damaged components.
Rear Differential Mounting Bolt Loosening
2017-02-28Reports of rear differential mounting bolts loosening on 2015-2018 Audi S8 vehicles. Improper torque or worn mounting components can contribute to this issue.
Resolution: Inspect rear differential mounts for wear. Remove and re-torque all rear differential mounting bolts to the proper specification. Replace any worn or damaged mounts or bolts.
CV Joint Bolt Loosening on Front Axle
2016-09-10Certain 2012-2016 Audi S8s have experienced front CV joint bolt loosening after repeated high-stress operation. Torque these to spec.
Resolution: Inspect CV joint bolts for signs of loosening or damage. Retorque all front CV joint bolts to proper specification. Ensure bolts are not stretched or damaged. Replace if necessary.
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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.
- 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.