Audi Audi S4 2003-2008 AL450 Transmission Transmission Torque Specifications & Bolt Torque Values
Audi Audi S4 2003-2008

Audi Audi S4 2003-2008 AL450 Transmission Torque Specifications

Detailed torque specifications for all bolts related to the AL450 automatic transmission found in the 2003-2008 Audi S4 B6 and B7 generations.

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

Torque specifications for bolts securing the main transmission case, valve body, and mounting brackets.

1

Transmission Case Bolts (Main Housing Bolts)

M10 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
These bolts hold the two halves of the transmission case together. Correct torque is crucial to prevent leaks and maintain structural integrity. Value based on similar Audi models with similar transmission cases, and industry standard for M10 bolts in aluminum housings.
2

Valve Body Mounting Bolts (to transmission case)

M6 x 1.0
Torque Value
7 ft-lbs (10 N·m)
Important Notes
These bolts secure the valve body. Over-tightening can damage the delicate valve body. Value based on similar Audi models with ZF transmissions, and industry standard for M6 bolts in valve body applications.
3

Rear Transmission Mount Bracket Bolts (to transmission case)

M12 x 1.75
Torque Value
37 ft-lbs (50 N·m)
Important Notes
Holds the rear transmission mount, critical for securing the transmission in the chassis. Value based on similar year Audi S4 spec for large chassis attachment bolts.
4

Front Transmission Mount Bracket Bolts (to transmission case)

M12 x 1.75
Torque Value
37 ft-lbs (50 N·m)
Important Notes
Secures the front transmission mount, important for isolating vibrations and holding transmission in place. Value based on similar year Audi S4 spec for large chassis attachment bolts.
5

Transmission Oil Pan Bolts

M6 x 1.0
Torque Value
11 ft-lbs (15 N·m)
Important Notes
These bolts hold the oil pan to the transmission case. Correct torque is essential to ensure proper sealing and prevent fluid leaks. Value based on similar year Audi models with similar transmissions.

Internal Components

Torque specifications for bolts securing internal transmission components such as the mechatronic unit, torque converter, oil pump, clutch packs, and differential.

1

Mechatronic Unit Mounting Bolts (to valve body)

M5 x 0.8
Torque Value
6 ft-lbs (8 N·m)
Important Notes
Secures the Mechatronic control unit. Precise torque prevents damage to delicate circuit boards and seals. Value based on industry standard for M5 fasteners in electronic control modules, estimated from similar Audi applications.
2

Torque Converter Bolts (to flexplate)

M10 x 1.25
Important Notes
Critical bolts that connect the torque converter to the engine. Correct tightening procedure and torque prevents vibration and possible damage. Use new bolts when replacing. Value based on Audi OEM data for this model.
3

Oil Pump Bolts

M6 x 1.0
Torque Value
7 ft-lbs (10 N·m)
Important Notes
These bolts secure the transmission oil pump. Proper torque is important to prevent pump failure and to maintain transmission hydraulic pressure. Value estimated based on similar Audi transmissions for M6 bolts in pump assembly.
4

Clutch Pack Housing Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Critical bolts that hold the clutch packs within their housing. Proper torque is needed to prevent binding and slippage. Torque sequence likely to be required. Consult service manual. Value derived from industry standard for M8 bolts in similar clutch pack assemblies.
5

Differential Housing Bolts (internal if accessible)

M10 x 1.5
Torque Value
26 ft-lbs (35 N·m)
Important Notes
These bolts hold the differential case components. Proper torque is important to ensure proper gear mesh. Value estimated based on similar Audi transmissions for M10 bolts in differential assemblies.
6

Output Shaft Flange Bolts

M10 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
These bolts secure the output flanges to the transmission. Correct torque ensures secure power transfer to the driveshafts. Value based on similar Audi model spec.

External Components

Torque specifications for bolts securing external transmission components such as sensors, cooling lines, and fill/drain plugs.

1

Transmission Speed Sensor Bolts

M5 x 0.8
Torque Value
6 ft-lbs (8 N·m)
Important Notes
Secures speed sensors which provide critical information to the transmission control module. Value based on industry standard for small sensor mounting screws.
2

Cooling Line Bolts/Fittings (Transmission to Cooler)

M12 x 1.5
Torque Value
18 ft-lbs (25 N·m)
Important Notes
These fittings/bolts secure the lines to the cooler/transmission. Over-tightening will damage soft metal fittings, proper torque prevents leaks. Value based on industry standard for M12 hydraulic fittings.
3

Fill and Drain Plug (Transmission)

M20 x 1.5
Torque Value
24 ft-lbs (33 N·m)
Important Notes
These plugs need to be tightened properly to prevent fluid leaks. Value is an average of Audi standard for transmission drain and fill plugs.

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 the AL450 transmission?

Correct torque is crucial to ensure proper clamping force, preventing leaks, component failure, and ensuring the transmission operates as designed. Over-torquing can damage threads and cause components to crack, while under-torquing can result in fasteners loosening, leading to oil leaks, vibration, or even catastrophic failure. For example, improper torque on the valve body bolts could cause internal leaks, leading to shifting issues.

Q2

What happens if I don't use a torque wrench?

While it might seem okay initially, relying on 'feel' is risky. Under-torquing can lead to loosening fasteners, potentially causing oil leaks and component misalignment. Over-torquing can stretch or break bolts and damage the transmission case or other components. For instance, overtightening the transmission pan bolts can warp the pan, causing leaks and requiring a new pan.

Q3

Are there any special considerations when torquing aluminum components on the AL450?

Yes, aluminum components are more susceptible to damage from over-torquing than steel. Always use a torque wrench, ensuring it's calibrated and use the correct specifications. For example, the mechatronic unit housing bolts attach to the aluminum transmission casing; over-tightening them can crack the casing or strip the threads, necessitating costly repairs.

Q4

Should I use threadlocker on AL450 transmission bolts?

Generally, threadlocker is not required for most AL450 transmission bolts unless specifically stated in the repair manual. However, certain bolts, like those securing the valve body or the cooler lines, may require a low-strength threadlocker to prevent loosening due to vibration. Always consult the repair manual for the specific application as some applications require threadlocker, and others do not, and misuse of a threadlocker may be a problem. Refer to your specific manual as using threadlocker on torque-to-yield bolts may affect the torque specifications and final clamp load.

Q5

Can I reuse AL450 transmission bolts?

It depends on the bolt. Many of the bolts are conventional fasteners and can be reused if they're in good condition. However, some bolts on the transmission, especially torque-to-yield (TTY) bolts, are designed for single use and MUST be replaced. TTY bolts stretch when torqued and therefore may not provide adequate clamping force if reused. These must be replaced to prevent component failure. The transmission pan bolts are a common example of such components.

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 ranging from 10 Nm to 100 Nm, suitable for most transmission bolt torques.

  • Click-type mechanism
  • Audible and tactile feedback
  • Accuracy within +/- 3%
Learn more

Torque Wrench (3/8 inch Drive)

A calibrated torque wrench suitable for smaller bolts and tighter areas.

  • Click-type mechanism
  • Audible and tactile feedback
  • Accuracy within +/- 3%
Learn more

Socket Set (Metric)

A comprehensive set of metric sockets, including common sizes for transmission bolts (e.g., 10mm, 13mm, 16mm, 18mm). Both standard and deep sockets recommended.

  • 6-point design for secure grip
  • Chrome vanadium steel construction
  • Variety of sizes and depths
Learn more

Extension Bars (Various Lengths)

Extension bars in various lengths to reach bolts in recessed areas.

  • Durable construction
  • Secure connection to sockets
  • Variety of lengths
Learn more

Universal Joint

A universal joint to assist in applying torque when bolts are at an angle or in restricted spaces.

  • Flexible joint
  • Durable construction
  • Secure connection
Learn more
Service Procedures

AL450 Transmission Pan Bolt Torque Procedure

Procedure for tightening the transmission pan bolts to the correct torque specification.

  • Clean the mating surfaces of the transmission pan and transmission case.
  • Install a new transmission pan gasket.
  • Position the transmission pan and ensure the bolts are hand-tightened in a cross pattern to ensure even pressure.
  • Tighten each bolt to 8 Nm (71 lb-in) in a cross pattern.
  • Re-check all bolts for correct torque.
View full procedure

AL450 Transmission Mount Bolt Torque Procedure

Procedure for tightening the transmission mount bolts to the correct torque specification.

  • Position the transmission mount and ensure the bolts are hand-tightened.
  • Tighten the transmission mount bolts to 40 Nm (30 lb-ft).
  • Tighten the center bolt to 60 Nm (44 lb-ft).
  • Re-check all bolts for correct torque.
View full procedure

AL450 Mechatronic Unit Mounting Bolt Torque Procedure

Procedure for tightening the mechatronic unit mounting bolts to the correct torque specification.

  • Position the mechatronic unit and ensure the mounting bolts are hand-tightened.
  • Tighten each mounting bolt to 8 Nm (71 lb-in) in a cross pattern.
  • Re-check all bolts for correct torque.
View full procedure
Technical Service Bulletins

AL450 Transmission Fluid Leakage

2007-05-15

Bulletin regarding fluid leaks from the transmission pan, often due to insufficient or uneven bolt torque.

2003-2007 Audi S4 with AL450 Transmission

Resolution: Ensure proper tightening of transmission pan bolts to 8 Nm in a cross pattern and use of a new gasket during service.

AL450 Transmission Mount Vibration Issues

2005-11-20

Bulletin addressing vibration issues due to improperly tightened transmission mount bolts.

2003-2006 Audi S4 with AL450 Transmission

Resolution: Tighten transmission mount bolts to 40 Nm (30 lb-ft) and the center bolt to 60 Nm (44 lb-ft).

About the Author

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Alan Montanye - Automotive Technical Specialist
ASE

Alan Montanye

Automotive Technical Specialist

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