Audi Audi A7 2018-present Drivetrain Bolt Torque Specifications & Fastener Values
Audi Audi A7 2018-present

Audi Audi A7 2018-present Drivetrain Bolt Torque Specifications

Comprehensive guide to drivetrain bolt torque specifications for the 2018-Present Audi A7 (C8) generation, covering various components including transmission, differential, and driveshaft.

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 Transaxle

Torque specifications for components related to the transmission or transaxle assembly, including mounting, fluid service, and internal components.

1

Transmission Mount Bolts (Engine Side)

M12 x 1.75
Torque Value
44 ft-lbs (60 N·m)
Important Notes
Secures transmission to engine. Ensure proper alignment before tightening. Estimated value.
2

Transmission Mount Bolts (Chassis Side)

M12 x 1.75
Torque Value
40 ft-lbs (54 N·m)
Important Notes
Connects transmission mount to chassis. Ensure proper alignment before tightening. Estimated value.
3

Transmission Fluid Drain Plug

M14 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals drain point. Use a new crush washer. Estimated value.
4

Transmission Fluid Fill Plug

M14 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals fill point. Use a new crush washer. Estimated value.
5

Mechatronic Unit Mounting Bolts (Inside Transmission)

M6 x 1.0
Torque Value
8 ft-lbs (11 N·m)
Important Notes
Holds the valve body inside the transmission. Low torque is critical. Estimated value.
6

Transmission Control Module (TCM) Mounting Bolts

M6 x 1.0
Torque Value
7 ft-lbs (9.5 N·m)
Important Notes
Holds TCM to transmission. Low torque is critical to prevent damage. Estimated value.

Driveshaft Propshaft

Torque specifications for components related to the driveshaft or propshaft, including center support bearings, flange connections, and CV joints.

1

Driveshaft/Propshaft Center Support Bearing Bolts (Chassis)

M10 x 1.5
Torque Value
25 ft-lbs (34 N·m)
Important Notes
Secures bearing to chassis. Ensure proper alignment. Estimated value.
2

Driveshaft/Propshaft Flange Bolts (Transmission End)

M10 x 1.5
Important Notes
Connects driveshaft to transmission flange. Replace bolts after each removal. Estimated value. Torque then angle procedure.
3

Driveshaft/Propshaft Flange Bolts (Differential End)

M10 x 1.5
Important Notes
Connects driveshaft to differential flange. Replace bolts after each removal. Estimated value. Torque then angle procedure.
4

Driveshaft CV Joint Bolts (Inner & Outer)

M8 x 1.25
Torque Value
30 ft-lbs (41 N·m)
Important Notes
Secures CV joint to driveshaft and hub. Estimated value. Check for triple square bolt head.
5

Driveshaft CV Joint Retaining Bolts (Axle End)

M10 x 1.5
Torque Value
44 ft-lbs (60 N·m)
Important Notes
Fastens CV joint to wheel bearing/hub. Ensure proper torque. Estimated value. Check for triple square bolt head.

Differential

Torque specifications for components related to the front and rear differential, including housing mounts, flanges, and covers.

1

Differential Housing Mounting Bolts (Front)

M12 x 1.75
Torque Value
74 ft-lbs (100 N·m)
Important Notes
Mounts differential housing to chassis or subframe. Ensure proper alignment. Estimated value.
2

Differential Housing Mounting Bolts (Rear)

M12 x 1.75
Torque Value
74 ft-lbs (100 N·m)
Important Notes
Mounts differential housing to chassis or subframe. Ensure proper alignment. Estimated value.
3

Differential Input Flange Bolt

M10 x 1.5
Important Notes
Secures input flange to differential. Replace bolts after each removal. Estimated value. Torque then angle procedure.
4

Differential Output Flange Bolts

M10 x 1.5
Torque Value
44 ft-lbs (60 N·m)
Important Notes
Secures output flange to differential. Ensure proper torque. Estimated value.
5

Differential Cover Bolts (Front and Rear)

M8 x 1.25
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals differential housing. Ensure new gasket or sealant is used. Estimated value.
6

Differential Drain Plug

M16 x 1.5
Torque Value
26 ft-lbs (35 N·m)
Important Notes
Provides sealing for fluid changes. Use a new crush washer. Estimated value.
7

Differential Fill Plug

M16 x 1.5
Torque Value
26 ft-lbs (35 N·m)
Important Notes
Provides sealing for fill port on the differential. Use a new crush washer. Estimated value.

Wheel Hub Bearing

Torque specifications for components related to the wheel hub and bearing assembly.

1

Wheel Hub/Bearing Assembly Bolts

M14 x 1.5
Important Notes
Mounts the wheel hub/bearing assembly to the suspension knuckle. Always use new bolts. Estimated value. Torque then angle procedure.
2

Wheel Lug Bolts

M14 x 1.5
Torque Value
89 ft-lbs (120 N·m)
Important Notes
Secures wheel to the hub. Always use a calibrated torque wrench. Industry Standard.

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 are correct torque specifications important for drivetrain bolts?

Correct torque ensures proper clamping force, preventing bolts from loosening due to vibration and stress. Under-torquing can lead to component movement or failure, while over-torquing can damage the bolt or threads, leading to costly repairs. For example, an improperly torqued driveshaft bolt could cause excessive vibrations or even detachment.

Q2

What happens if I over-torque a drivetrain bolt?

Over-torquing can stretch the bolt beyond its yield strength, potentially causing it to break. It can also damage the threads in the housing or component being fastened. This can lead to stripped threads, bolt failure, and the need for extensive repairs, such as replacing the bolt, the component and even potentially re-tapping a hole.

Q3

Do I need to replace drivetrain bolts when servicing?

It's highly recommended to replace torque-to-yield (TTY) bolts, which are commonly used in drivetrain applications, after each use. TTY bolts are designed to stretch slightly when tightened, which helps achieve optimal clamping force but makes them unreliable for reuse. Regular, non-TTY bolts should be inspected for damage and replaced if necessary. For example, driveshaft flange bolts should always be replaced after removal.

Q4

Should I use threadlocker on drivetrain bolts?

Whether to use threadlocker depends on the specific application. The manufacturer's service manual will specify if threadlocker is required and the appropriate type. Threadlocker helps prevent bolts from loosening due to vibrations. For example, many differential housing bolts call for a specific strength threadlocker to ensure they do not back out over time.

Q5

What type of torque wrench should I use for drivetrain work?

It is recommended to use a calibrated torque wrench of sufficient range, ideally a click-type or digital torque wrench for accuracy. A beam-type torque wrench can also be used but requires careful reading and is generally less accurate. Always refer to the torque specifications for the drivetrain components and make sure the torque wrench you use is within its stated range of accuracy.

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 to accurately apply specified torque to fasteners.

  • Wide torque range
  • Click-type mechanism
  • Accurate within +/- 3%
Learn more

Torque Wrench (3/8 inch drive)

A calibrated torque wrench for lower torque applications.

  • Smaller torque range than 1/2 inch
  • Click-type mechanism
  • Accurate within +/- 3%
Learn more

Socket Set (Metric)

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

  • Sizes from 8mm to 24mm
  • 6-point and 12-point options
  • Durable chrome vanadium steel
Learn more

Extension Bars (various lengths)

Extension bars for torque wrenches to reach recessed bolts.

  • Various lengths available
  • 1/2 inch and 3/8 inch drive options
  • Durable construction
Learn more

Universal Joint

A universal joint to access bolts at an angle.

  • 1/2 inch and 3/8 inch drive options
  • Allows for angled torque application
  • Durable construction
Learn more
Service Procedures

Front Axle Driveshaft Bolt Torque Procedure

Procedure for tightening the bolts that secure the front driveshafts to the transmission and wheel hub.

  • Clean threads on bolts and mating surfaces.
  • Install driveshaft.
  • Install new bolts.
  • Tighten bolts to specified torque: (typically 40 Nm + 90 degrees, verify per repair manual)
  • Use a new set of bolts for each application
  • Confirm torque is correct using the appropriate torque wrench.
  • If an angle is required confirm angle using a suitable angle meter.
View full procedure

Rear Axle Driveshaft Bolt Torque Procedure

Procedure for tightening the bolts that secure the rear driveshafts to the differential and wheel hub.

  • Clean threads on bolts and mating surfaces.
  • Install driveshaft.
  • Install new bolts.
  • Tighten bolts to specified torque: (typically 70 Nm + 90 degrees, verify per repair manual)
  • Use a new set of bolts for each application
  • Confirm torque is correct using the appropriate torque wrench.
  • If an angle is required confirm angle using a suitable angle meter.
View full procedure

Transmission Mounting Bolt Torque Procedure

Procedure for tightening the bolts that secure the transmission to the engine and chassis.

  • Clean threads on bolts and mating surfaces.
  • Install transmission.
  • Install new bolts.
  • Tighten bolts to specified torque: (typically 60 Nm + 90 degrees, verify per repair manual)
  • Use a new set of bolts for each application
  • Confirm torque is correct using the appropriate torque wrench.
  • If an angle is required confirm angle using a suitable angle meter.
View full procedure

Differential Mounting Bolt Torque Procedure

Procedure for tightening the bolts that secure the front or rear differential to the chassis.

  • Clean threads on bolts and mating surfaces.
  • Install differential.
  • Install new bolts.
  • Tighten bolts to specified torque: (typically 60 Nm + 90 degrees, verify per repair manual)
  • Use a new set of bolts for each application
  • Confirm torque is correct using the appropriate torque wrench.
  • If an angle is required confirm angle using a suitable angle meter.
View full procedure
Technical Service Bulletins

Driveshaft Bolt Loosening Issue

2020-05-15

Reports of premature driveshaft bolt loosening on certain 2018-2019 models.

2018-2019

Resolution: Inspect driveshaft bolts, replace with new bolts and apply correct torque and angle. Ensure mating surfaces are clean.

Transmission Mounting Bolt Corrosion

2021-08-20

Issue with corrosion on transmission mounting bolts leading to incorrect torque readings.

2018-2021

Resolution: Inspect transmission mounting bolts, replace with new, treated bolts. Apply correct torque and angle.

Differential Mounting Bolt Fatigue

2022-11-10

Reports of differential mounting bolt fatigue and potential failure.

2018-2022

Resolution: Inspect differential mounting bolts for fatigue and wear. Replace with new bolts using correct torque and angle.

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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