Audi Audi A8 2018-present DL501 Transmission Transmission Torque Specifications & Bolt Torque Values
Audi Audi A8 2018-present

Audi Audi A8 2018-present DL501 Transmission Torque Specifications

Detailed torque specifications for the DL501 transmission bolts found in the 2018-Present Audi A8 (D5) models. Includes information on bolt locations and tightening procedures.

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 Housing And Mounting

Components related to securing the transmission to the engine and chassis.

1

Transmission to Engine Bolts

M12 x 1.5
Torque Value
59 ft-lbs (80 N·m)
Important Notes
These bolts secure the transmission to the engine block. Correct torque is crucial for maintaining proper alignment and preventing leaks.
2

Transmission Mount to Chassis Bolts

M10 x 1.5
Torque Value
41 ft-lbs (55 N·m)
Important Notes
Secures the transmission mount to the chassis. Correct torque is vital for vibration control.
3

Transmission Mount to Transmission Housing Bolts

M10 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
Fasteners secure the mount to the transmission case. Proper torque prevents loosening.
4

Transmission Housing Bolts

M8 x 1.25
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Bolts join the transmission case halves. Even torque distribution and sequence is essential. Use a criss-cross pattern. Estimated value.

Mechatronics Unit And Components

Fasteners for the Mechatronics unit, valve body and related components.

1

Mechatronics Unit to Transmission Case Bolts

M6 x 1.0
Torque Value
7 ft-lbs (10 N·m)
Important Notes
Fasten the Mechatronics unit to the transmission case. Correct torque is very important as over tightening may crack the valve body. Estimated value. Use a torque sequence (refer to the workshop manual)
2

Solenoid Valve Retaining Screws

M5 x 0.8
Torque Value
4.5 ft-lbs (6 N·m)
Important Notes
Holds solenoid valves in place on the mechatronics unit. Correct torque is crucial to secure valves and prevent internal leaks. Estimated value.
3

Pressure Sensor Retaining Screws

M4 x 0.7
Torque Value
2.2 ft-lbs (3 N·m)
Important Notes
Secures pressure sensors to the transmission or valve body. Correct torque is essential for proper sensor function. Estimated value.

Internal Components And Fasteners

Fasteners for internal components within the transmission.

1

Transmission Pan Bolts

M6 x 1.0
Torque Value
7 ft-lbs (10 N·m)
Important Notes
Secures the transmission pan to the housing. Even torque ensures a leak-proof seal. Use a criss-cross tightening sequence.
2

Transmission Fluid Drain Plug

M24 x 1.5
Torque Value
26 ft-lbs (35 N·m)
Important Notes
Seals the fluid drain opening. Always replace sealing washer upon installation.
3

Transmission Fill Plug

M18 x 1.5
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Seals the fill port. Prevents leaks and ensures the integrity of the sealing washer. Always replace the sealing washer when installing.
4

Clutch Pack Retaining Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
These bolts hold the clutch assembly components together. These bolts typically require a torque sequence. Estimated value, refer to the service manual for detailed torque sequence procedure.
5

Differential Mounting Bolts to Transmission Case

M10 x 1.5
Torque Value
41 ft-lbs (55 N·m)
Important Notes
Fastens the differential to the transmission housing. Correct torque ensures proper alignment and prevents vibration and damage.
6

Input/Output Speed Sensor Bolts

M6 x 1.0
Torque Value
7 ft-lbs (10 N·m)
Important Notes
Secures the input and output speed sensors. Correct torque is crucial for accurate readings. Over tightening could crack the sensor casing. Estimated value.
7

Valve Body Mounting Screws

M5 x 0.8
Torque Value
4.5 ft-lbs (6 N·m)
Important Notes
Fastens the valve body to the transmission case or Mechatronics unit. Proper torque is vital to avoid leaks and maintain proper functioning of hydraulic circuits. Use a torque sequence (refer to the workshop manual). Estimated value
8

Oil Pump Housing Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Secures the oil pump to the transmission. Proper torque prevents leaks and ensures proper pump operation. Estimated value based on industry-standard practice.

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 crucial for DL501 transmission bolts?

Correct torque is essential to ensure proper clamping force, preventing bolt loosening due to vibrations, which can lead to fluid leaks, component damage, or transmission failure. Over-tightening can cause bolt stretching, thread damage, or even cracking of the transmission housing, while under-tightening leads to insufficient clamping, which could cause leaks or components to move under stress.

Q2

What happens if I over-torque a DL501 transmission bolt?

Over-torquing can permanently damage the bolt and/or the threads in the transmission case. This often results in bolt stretching or breakage, and possibly cracking of the housing around the bolt. In a worst-case scenario, this requires expensive repairs, including potential transmission removal and housing replacement.

Q3

Can I reuse DL501 transmission bolts, and if not, why?

Generally, no. Many DL501 transmission bolts, especially those related to critical areas, are designed for single use. They are often torque-to-yield (TTY) bolts, which stretch when properly tightened. Once stretched, they cannot be reused reliably and should be replaced with new bolts to ensure proper clamping force and prevent future issues.

Q4

Where can I find the correct torque specifications for my specific Audi A8 DL501 transmission?

The specific torque values should be in your vehicle's repair manual or a reputable online database for Audi repair information. Always use the exact torque specification for your model year. Be aware that various bolts within the transmission may have different torque specifications, so double-check each bolt's size and location against the repair information.

Q5

Should I use threadlocker on DL501 transmission bolts?

The need for threadlocker depends on the specific bolt and its location within the DL501 transmission. Some bolts come pre-treated with threadlocker or have a locking mechanism integrated. The official Audi repair procedure will specify which bolts, if any, require the application of threadlocker. It is critical to use the proper strength threadlocker if it is specified and avoid using it if not.

Q6

What tool is recommended for tightening transmission bolts?

Always use a calibrated torque wrench when tightening any bolt in the DL501 Transmission. This ensures an accurate torque reading. It is recommended to use a good quality torque wrench and check its calibration at regular intervals. Using an impact gun is never recommended as it is impossible to control torque accurately.

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 capable of measuring torque values within the specified range for the DL501 transmission bolts.

  • Accurate torque measurement
  • Audible click when target torque is reached
Learn more

Torque Wrench (3/8-inch drive)

A calibrated torque wrench capable of measuring torque values within the specified range for the smaller DL501 transmission bolts.

  • Accurate torque measurement
  • Smaller profile for tighter spaces
Learn more

Socket Set (Metric)

A comprehensive set of metric sockets, including sizes commonly used on the DL501 transmission.

  • Various sizes for different bolt heads
  • Durable construction
Learn more

Extension Bars (1/2-inch and 3/8-inch drive)

Extension bars to reach recessed bolts on the DL501 transmission.

  • Various lengths for different access requirements
  • Durable construction
Learn more

Universal Joint (1/2-inch and 3/8-inch drive)

Universal joints to provide angled access to bolts.

  • Flexible angle adjustment
  • Durable construction
Learn more
Service Procedures

DL501 Transmission Bolt Torque Procedure - Mechatronics Unit

Procedure for correctly torquing the bolts securing the mechatronics unit to the DL501 transmission.

  • Locate all the mechatronics unit bolts.
  • Clean threads of the bolts and tapped holes.
  • Install bolts by hand, ensure they are all engaged with threads.
  • Tighten all bolts in a crisscross pattern to 10 Nm (7.4 ft-lb).
  • Tighten all bolts in a crisscross pattern to 20 Nm (14.8 ft-lb).
  • Re-torque each bolt to 20 Nm (14.8 ft-lb) to confirm torque.
View full procedure

DL501 Transmission Bolt Torque Procedure - Transmission Housing Bolts

Procedure for correctly torquing the main housing bolts of the DL501 transmission.

  • Locate all the transmission housing bolts.
  • Clean threads of the bolts and tapped holes.
  • Install bolts by hand, ensure they are all engaged with threads.
  • Tighten all bolts in a crisscross pattern to 20 Nm (14.8 ft-lb).
  • Tighten all bolts in a crisscross pattern to 40 Nm (29.5 ft-lb).
  • Re-torque each bolt to 40 Nm (29.5 ft-lb) to confirm torque.
View full procedure

DL501 Transmission Bolt Torque Procedure - Oil Pan Bolts

Procedure for correctly torquing the oil pan bolts of the DL501 transmission.

  • Locate all the oil pan bolts.
  • Clean threads of the bolts and tapped holes.
  • Install bolts by hand, ensure they are all engaged with threads.
  • Tighten all bolts in a crisscross pattern to 10 Nm (7.4 ft-lb).
  • Re-torque each bolt to 10 Nm (7.4 ft-lb) to confirm torque.
View full procedure
Technical Service Bulletins

Potential Mechatronic Unit Bolt Loosening

2019-05-15

Some DL501 transmissions have been reported to experience loosening of the mechatronic unit bolts over time, potentially leading to transmission performance issues.

2018-2019 A8

Resolution: Verify torque specification of 20 Nm on mechatronic bolts. If previously tightened, it is advised to replace the bolts. Always use a properly calibrated torque wrench when applying torque to bolts.

Transmission Housing Bolt Inspection

2020-11-20

Bulletin regarding the inspection and torque of the transmission housing bolts on the DL501 transmission. Improper torque can lead to fluid leaks.

2018-2020 A8

Resolution: Verify correct torque spec of 40 Nm on all transmission housing bolts. Inspect for any signs of oil leaks around the housing. Follow specified bolt tightening pattern when tightening.

About the Author

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Alan Montanye - Automotive Technical Specialist
ASE

Alan Montanye

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