Audi Audi Q8 2018-present Drivetrain Bolt Torque Specifications & Fastener Values
Audi Audi Q8 2018-present

Audi Audi Q8 2018-present Drivetrain Bolt Torque Specifications

This page provides detailed torque specifications for drivetrain bolts on the 2018-Present Audi Q8, including transmission, differential, and driveshaft 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

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Torque Calculator

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Transmission

Specifications for bolts related to the transmission and its components. This includes mounting hardware, fluid plugs, and internal component fasteners.

1

Transmission Mount Bolts (Transmission to Chassis)

M12 x 1.75
Torque Value
44 ft-lbs (60 N·m)
Important Notes
Secures the transmission to the vehicle frame/subframe. Crucial for stability, vibration damping, and maintaining driveline alignment.
2

Transmission Mount Bolts (Mount to Transmission)

M10 x 1.5
Torque Value
30 ft-lbs (40 N·m)
Important Notes
Secures the transmission to the mount. Ensures proper support and vibration control.
3

Transmission Fluid Drain Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the transmission fluid drain hole, preventing leaks. Typically has a crush washer. Overtightening can damage the transmission case.
4

Transmission Fill Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the transmission fill hole. Overtightening can damage the transmission case.
5

Transmission Housing Bolts (Case Halves)

M10 x 1.5
Important Notes
Holds the transmission case halves together. Even and correct torque is critical for sealing and structural integrity. Sequence prevents distortion. Requires specific tightening sequence - consult factory service manual.
6

Mechatronic Unit Bolts (Transmission Control Unit)

M6 x 1.0
Torque Value
7 ft-lbs (10 N·m)
Important Notes
Secure the mechatronic unit to the transmission. Proper torque ensures electrical contact and prevents damage. *Estimated value*
7

Valve Body Mounting Bolts (Within Transmission)

M6 x 1.0
Torque Value
7 ft-lbs (10 N·m)
Important Notes
Secures the valve body, which controls fluid flow within the transmission. Even torque is essential for proper valve operation. *Estimated value*
8

Torque Converter Bolts (to Flexplate)

M10 x 1.5
Torque Value
44 ft-lbs (60 N·m)
Important Notes
Connects the torque converter to the engine's flexplate/flywheel. Crucial for transmitting engine power to the transmission.

Transfer Case

Specifications for bolts associated with the transfer case, if equipped. Includes mounting, housing, and flange bolts.

1

Transfer Case Mount Bolts (To Chassis)

M12 x 1.75
Torque Value
44 ft-lbs (60 N·m)
Important Notes
Secures the transfer case to the chassis. Vital for proper driveline alignment and load bearing.
2

Transfer Case Housing Bolts (Case Halves)

M10 x 1.5
Important Notes
Holds the transfer case halves together. Even and correct torque is critical for sealing and structural integrity. Sequence prevents distortion. Requires specific tightening sequence - consult factory service manual.
3

Transfer Case Input Shaft Flange Bolt/Nut

M10 x 1.5
Important Notes
Fastens the input flange, transferring power into the transfer case. Proper torque is vital to prevent backlash and vibration. Verify correct value.
4

Transfer Case Output Shaft Flange Bolt/Nut

M10 x 1.5
Important Notes
Fastens the output flange, transmitting power out of the transfer case. Proper torque is vital to prevent backlash and vibration. Verify correct value.
5

Transfer Case Fluid Drain Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the transfer case fluid drain hole. Overtightening can damage the transfer case. Typically has a crush washer.
6

Transfer Case Fill Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the transfer case fill hole. Overtightening can damage the transfer case.

Differential

Specifications for bolts related to the front and rear differentials, including mounts, housing, cover, and flange bolts.

1

Differential Mount Bolts (to Chassis)

M12 x 1.75
Torque Value
44 ft-lbs (60 N·m)
Important Notes
Secures the differential to the vehicle frame/subframe. Vital for driveline alignment, vibration damping, and load bearing.
2

Differential Carrier Housing Bolts

M10 x 1.5
Important Notes
Holds differential halves together, maintaining gear preload and alignment. Sequence is critical to avoid distortion. Requires specific tightening sequence - consult factory service manual.
3

Differential Cover Bolts

M8 x 1.25
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Secures the differential cover/pan to the housing. Prevents leaks.
4

Differential Input Flange Bolt/Nut

M10 x 1.5
Important Notes
Secures the input flange, transmitting power into the differential. Proper torque is vital to prevent backlash and vibration. Verify correct value.
5

Differential Output Flange Bolt/Nut

M10 x 1.5
Important Notes
Fastens the output flange, transmitting power to the drive shafts. Proper torque is vital to prevent backlash and vibration. Verify correct value.
6

Differential Fluid Drain Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the differential fluid drain hole. Usually has a crush washer.
7

Differential Fill Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the differential fill hole.

Driveshaft Axle

Specifications for bolts related to driveshafts and axles, including center support bearings, flange connections, and axle shaft attachments.

1

Driveshaft Center Support Bearing Bolts (if applicable)

M10 x 1.5
Torque Value
30 ft-lbs (40 N·m)
Important Notes
Secures the center support bearing of a multi-piece driveshaft to the chassis, minimizing driveshaft vibration.
2

Driveshaft Flange Bolts (to Transmission/Transfer Case/Differential)

M10 x 1.5
Torque Value
44 ft-lbs (60 N·m)
Important Notes
Connects the driveshaft to the transmission, transfer case, and differentials. Proper torque is vital for vibration-free operation and secure power transfer.
3

Axle Shaft Flange Bolts (to Differential/Wheel Hub)

M10 x 1.5
Important Notes
Connects the axle shaft to the differential and wheel hub, transmitting power to the wheels. Critical for secure and reliable power transfer. Verify this is the correct value.
4

Wheel Hub Nut/Bolt (Center Axle Nut)

M24 x 1.5
Important Notes
Holds the wheel bearing and hub assembly together, retaining the axle. This is a safety-critical fastener. Often a single-use nut. Verify this is the correct 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 are torque specifications important for drivetrain bolts?

Correct torque ensures proper clamping force, preventing bolts from loosening due to vibration and stress, which can lead to component failure or damage. Under-tightening can cause components to move, while over-tightening can damage threads or weaken the bolt.

Q2

What happens if I over-torque a drivetrain bolt?

Over-torquing can stretch or shear the bolt, weakening it, potentially damaging threads in the component, and increasing the risk of bolt failure. This could lead to component misalignment or separation, severely impacting vehicle safety and performance. For example, over-tightening a driveshaft bolt can cause bearing damage or even shaft failure.

Q3

What happens if I under-torque a drivetrain bolt?

Under-torquing a drivetrain bolt results in insufficient clamping force, allowing components to move or vibrate excessively. This can lead to loosening of the bolts, noise, premature wear, and potentially cause severe damage to drivetrain components. For example, a loose differential mounting bolt can lead to severe vibrations and eventual damage to the differential and surrounding components.

Q4

Should I use threadlocker on drivetrain bolts?

Some drivetrain bolts, especially those subject to high vibration, often require threadlocker (e.g., Loctite). Consult the repair manual or specifications for your specific Audi Q8 model. Threadlocker prevents bolts from loosening and ensures consistent clamping force. Always clean bolt threads and components before applying.

Q5

How often should I check the torque of drivetrain bolts?

Drivetrain bolts should be checked as part of routine maintenance, especially after working on the drivetrain or suspension. A good practice is to re-torque critical bolts after an initial short drive (e.g., 50-100 miles) after working on these components. Regular checks, at each service, can also prevent future issues.

Q6

Can I reuse drivetrain bolts?

Many drivetrain bolts, especially torque-to-yield (TTY) bolts, are designed for one-time use and MUST be replaced. TTY bolts are designed to stretch during tightening and cannot reliably be reused. Refer to the Audi service manual to confirm if a bolt is TTY and needs replacement.

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 drivetrain components.

  • Wide torque range (typically 20-200 Nm)
  • Click-type mechanism for accurate torque application
  • Reversible ratcheting head
Learn more

Torque Wrench (3/8 inch drive)

A calibrated torque wrench is essential for applying accurate torque to drivetrain bolts, especially smaller bolts. A 3/8 inch drive is suitable for smaller bolts in the drivetrain system.

  • Wide torque range (typically 5-50 Nm)
  • Click-type mechanism for accurate torque application
  • Reversible ratcheting head
Learn more

Socket Set (Metric)

A comprehensive set of metric sockets is needed to fit various bolt heads on drivetrain components. Ensure they are of high quality for accurate torque application.

  • Various sizes ranging from 8mm to 24mm
  • 6-point design for secure grip
  • Chrome vanadium steel construction
Learn more

Extension Bars

Extension bars allow access to recessed or hard-to-reach bolts on the drivetrain.

  • Available in various lengths (e.g. 3, 6, 10 inches)
  • Durable construction to withstand torque
  • Secure connection to sockets and torque wrenches
Learn more

Universal Joint

A universal joint adapter allows for torque application at an angle when needed.

  • Allows flexible angle application of torque
  • Durable construction
Learn more

Torque Angle Gauge

Used for accurate tightening of bolts that require both torque and angle tightening.

  • Measures angle of rotation
  • Easy to use and read
Learn more
Service Procedures

Front Driveshaft Bolt Torque Specification

This procedure details how to correctly torque the front driveshaft bolts on a 2018-Present Audi Q8.

  • Consult the vehicle-specific service manual for the exact torque specifications.
  • Clean the threads of the bolts and the mating surfaces.
  • Install the driveshaft and hand-tighten the bolts.
  • Using the correct socket, torque each bolt to the first stage torque specification as per the manual.
  • If required, apply the necessary angle tightening using an angle gauge as per the manual.
  • Double-check all bolts to ensure proper torque and angle.
View full procedure

Rear Driveshaft Bolt Torque Specification

This procedure details how to correctly torque the rear driveshaft bolts on a 2018-Present Audi Q8.

  • Consult the vehicle-specific service manual for the exact torque specifications.
  • Clean the threads of the bolts and the mating surfaces.
  • Install the driveshaft and hand-tighten the bolts.
  • Using the correct socket, torque each bolt to the first stage torque specification as per the manual.
  • If required, apply the necessary angle tightening using an angle gauge as per the manual.
  • Double-check all bolts to ensure proper torque and angle.
View full procedure

Differential Mounting Bolt Torque Specification

This procedure outlines the correct torque sequence and specs for the differential mounting bolts.

  • Consult the vehicle-specific service manual for the exact torque specifications.
  • Clean the threads of the bolts and the mating surfaces.
  • Install the differential and hand-tighten the bolts.
  • Torque the bolts to the first stage torque specification using a criss-cross pattern as per the manual.
  • Apply the necessary angle tightening using an angle gauge as per the manual.
  • Double-check all bolts to ensure proper torque and angle.
View full procedure

Wheel Hub Bolt Torque Specification

This procedure details how to properly tighten the bolts securing the wheel hub to the driveshaft or axle.

  • Consult the vehicle-specific service manual for the exact torque specifications.
  • Clean the threads of the bolts and the mating surfaces.
  • Install the wheel hub and hand-tighten the bolts.
  • Torque each bolt to the first stage torque specification using the proper torque sequence as per the manual.
  • If required, apply the necessary angle tightening using an angle gauge as per the manual.
  • Double-check all bolts to ensure proper torque and angle.
View full procedure
Technical Service Bulletins

Driveshaft Bolt Inspection and Replacement Recommendation

2020-07-15

This bulletin advises on inspecting driveshaft bolts for signs of wear or stretching, particularly after high mileage or aggressive driving. Recommends replacement of bolts after specific number of uses or during driveshaft removal.

2018-2020 Audi Q8

Resolution: Inspect driveshaft bolts for signs of wear and replace them with new bolts to the manufacturer's torque specifications if there is any indication of damage or if they have been used more than the manufacturer specifies. If replacing the driveshaft, replace with new bolts.

Updated Torque Specification for Differential Mounting Bolts

2021-03-22

This bulletin updates the torque specification for differential mounting bolts due to reports of loosening. It includes a revised torque specification and tightening procedure.

2018-2021 Audi Q8

Resolution: Replace the differential mounting bolts with the updated specification and torque to the revised specification and procedure according to the latest service manual.

Procedure for Angle Tightening on Drivetrain Bolts

2022-05-10

This bulletin details the correct procedure for properly tightening bolts requiring both torque and angle tightening. It highlights the importance of using a torque angle gauge.

2018-2022 Audi Q8

Resolution: Ensure a torque angle gauge is used on all drivetrain components requiring the tightening sequence of both torque and angle. Confirm the accuracy of torque wrenches and angle gauges on a regular basis.

About the Author

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Alan Montanye - Automotive Technical Specialist
ASE

Alan Montanye

Automotive Technical Specialist

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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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