BMW 840i 2018-present Drivetrain Bolt Torque Specifications & Fastener Values
BMW 840i 2018-present

BMW 840i 2018-present Drivetrain Bolt Torque Specifications

This page provides detailed torque specifications for various drivetrain bolts on the 2018-Present BMW 840i (G14, G15, G16) models, including the driveshaft, differential, and axle 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

Search Specifications

Search by component name, bolt size, or description

Torque Calculator

Convert between different torque units

Engine Interface

These specifications cover the critical connections between the engine and the transmission, including the flywheel and related components. Proper torque is crucial for reliable power transfer and preventing vibration.

1

Flywheel Bolts

M12 x 1.5
Torque Value
74 ft-lbs (100 N·m)
Important Notes
Use a star pattern sequence for tightening. Ensure threads are clean and lightly lubricated with engine oil. Always replace if removed.

Transmission

These specifications detail the torque values for various components of the transmission assembly, including mounting bolts, oil pan, and drain plugs. Correct torque is essential for structural integrity and preventing fluid leaks.

1

Transmission Mounting Bolts

M10 x 1.5
Torque Value
48 ft-lbs (65 N·m)
Important Notes
These bolts secure the transmission to the engine block. Ensure proper alignment before tightening. Use a cross tightening pattern. Always replace if removed.
2

Transmission Oil Pan Bolts

M6 x 1.0
Torque Value
8 ft-lbs (11 N·m)
Important Notes
Tighten in a cross pattern to ensure even gasket compression. Do not overtighten as it may cause gasket leaks.
3

Transmission Drain and Fill Plugs

M18 x 1.5
Torque Value
29 ft-lbs (40 N·m)
Important Notes
Use new crush washers for the drain and fill plugs. Do not overtighten.
4

Transmission to Transfer Case Bolts

M10 x 1.5
Torque Value
48 ft-lbs (65 N·m)
Important Notes
Estimated value. This applies to AWD models only. Ensure proper alignment before tightening. Use a cross tightening pattern. Always replace if removed.

Drive Axles

Specifications for securing the drive axles to the transmission and wheel hubs. This section ensures proper power delivery to the wheels and correct bearing preload.

1

Drive Axle/Half Shaft Bolts

M10 x 1.5
Torque Value
63 ft-lbs (85 N·m)
Important Notes
These bolts secure the drive axle to the transmission or wheel hub. Ensure the bolts are lightly lubricated before installing. Use a cross tightening pattern.
2

CV Joint/Axle Nut

M24 x 1.5
Torque Value
148 ft-lbs (200 N·m)
Important Notes
This nut secures the CV joint to the wheel hub. It is critical for proper bearing preload. Use a new axle nut whenever removed.

Driveshaft

These specifications are for the bolts connecting the driveshaft to the transmission and differential. Proper torque is critical for smooth and reliable power transfer to the rear axle.

1

Propeller/Drive Shaft Bolts (Front)

M10 x 1.5
Torque Value
74 ft-lbs (100 N·m)
Important Notes
Use a cross pattern for tightening the bolts evenly. Ensure bolts are lightly lubricated before installing. Always replace if removed.
2

Rear Driveshaft Flange Bolts (Connecting to the Differential)

M10 x 1.5
Torque Value
74 ft-lbs (100 N·m)
Important Notes
Ensure proper alignment of the driveshaft to the differential flange. Use a cross pattern for tightening the bolts evenly. Always replace if removed.

Differential

This section covers the mounting bolts and service plugs for the differential. Proper torque is vital for maintaining correct alignment, securing the differential to the chassis, and preventing fluid leaks.

1

Differential Mounting Bolts

M12 x 1.75
Torque Value
74 ft-lbs (100 N·m)
Important Notes
Estimated value. Torque these bolts in a cross pattern to ensure even pressure. Always replace if removed.
2

Differential Drain/Fill Plug

M22 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
Always use new crush washers for the drain and fill plugs. Do not overtighten.

Transfer Case

These specifications are specific to all-wheel-drive (AWD) vehicles and concern the service plugs for the transfer case. Correct torque values are needed to ensure proper sealing and fluid containment.

1

Transfer Case Drain/Fill Plug

M18 x 1.5
Torque Value
29 ft-lbs (40 N·m)
Important Notes
Always use new crush washers for the drain and fill plugs. Do not overtighten.

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 is it important to use the correct torque specifications when working on the drivetrain?

Using the correct torque specifications is crucial for several reasons. Under-torqued bolts can loosen over time due to vibration, leading to component failure or damage. Over-torqued bolts can stretch or break, potentially causing similar problems, and can even damage the threaded holes. Correct torque ensures optimal clamping force, prevents stress on components, and ensures the long-term reliability of the drivetrain system. For example, improperly torqued driveshaft bolts could result in severe vibration or a complete failure.

Q2

Where can I find the correct torque specifications for my BMW 840i's drivetrain components?

The most accurate and reliable source for torque specifications is the BMW repair manual specific to your 840i's model year. You can also find information in reputable online automotive databases or from a certified BMW technician. Always double-check the information to confirm it's correct for your exact vehicle configuration. General forums should be used cautiously, as information there might not be correct or up to date.

Q3

Should I use new bolts when reassembling drivetrain components?

In many cases, yes. BMW often recommends using new bolts, especially for critical components like the driveshaft, differential, and transmission mounts. These bolts are often designed to stretch slightly upon torquing (torque-to-yield), and reusing them could result in incorrect clamping force, leading to problems later on. Refer to the repair manual for specific recommendations regarding bolt replacement.

Q4

What tools do I need to properly torque drivetrain bolts?

You will need a calibrated torque wrench capable of measuring torque within the required range for the drivetrain components. A set of sockets matching the bolt sizes, and possibly extensions or swivels, may also be needed to access the bolts. Always ensure the torque wrench is calibrated regularly for accurate measurements. Avoid using impact wrenches to tighten bolts to their final torque specification.

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" Drive)

A 1/2" drive torque wrench is essential for accurately tightening drivetrain bolts to the manufacturer's specifications.

  • Wide torque range (e.g., 20-200 Nm)
  • Click-type or digital display
  • Accurate within +/- 2%
Learn more

Torque Wrench (3/8" Drive)

A 3/8" drive torque wrench is needed for smaller, less torque-intensive bolts in the drivetrain.

  • Lower torque range (e.g., 5-60 Nm)
  • Click-type or digital display
  • Accurate within +/- 2%
Learn more

Socket Set (Metric)

A comprehensive metric socket set is necessary to fit the various bolt heads on the drivetrain.

  • Sizes ranging from 8mm to 24mm
  • 6-point sockets for better grip
  • Various extensions and adapters
Learn more

Universal Joint

Allows access to bolts in difficult to reach locations.

  • Allows socket to swivel on an angle
  • Standard 1/2" and 3/8" drives
Learn more
Service Procedures

Driveshaft Bolt Torque Procedure (Transmission Side)

Procedure for properly tightening the driveshaft bolts to the output flange of the transmission.

  • Clean all mating surfaces and bolt threads.
  • Install new bolts, or reuse bolts that are in excellent condition.
  • Initially tighten all bolts by hand until snug.
  • Using the appropriate torque wrench, tighten all bolts in a star pattern to 60 Nm.
  • Double-check each bolt with the torque wrench to ensure accurate torque.
View full procedure

Driveshaft Bolt Torque Procedure (Differential Side)

Procedure for properly tightening the driveshaft bolts to the input flange of the differential.

  • Clean all mating surfaces and bolt threads.
  • Install new bolts, or reuse bolts that are in excellent condition.
  • Initially tighten all bolts by hand until snug.
  • Using the appropriate torque wrench, tighten all bolts in a star pattern to 60 Nm.
  • Double-check each bolt with the torque wrench to ensure accurate torque.
View full procedure

Differential Mounting Bolt Torque Procedure

Procedure for correctly torqueing the bolts that attach the differential to the chassis.

  • Clean all mating surfaces and bolt threads.
  • Install new bolts, or reuse bolts that are in excellent condition.
  • Initially tighten all bolts by hand until snug.
  • Using the appropriate torque wrench, tighten all bolts in a star pattern to 100 Nm.
  • Double-check each bolt with the torque wrench to ensure accurate torque.
View full procedure

Wheel Hub Nut Torque Procedure

Procedure for properly tightening the wheel hub nut to the vehicle's specification.

  • Install new nut.
  • Initially tighten the nut by hand until snug.
  • Using the appropriate torque wrench, tighten to 300 Nm
  • Double-check the nut with the torque wrench to ensure accurate torque.
View full procedure
Technical Service Bulletins

Driveshaft Bolt Loosening Concerns

2021-05-15

Some instances of driveshaft bolt loosening have been reported. This bulletin outlines inspection and tightening procedures.

2018-2021 BMW 840i

Resolution: Inspect driveshaft bolts for signs of damage or looseness. Follow the specified torque procedure for tightening, and replace bolts if necessary.

Differential Mounting Bolt Corrosion Advisory

2022-08-20

Vehicles operating in high corrosion environments may experience corrosion on differential mounting bolts. This bulletin outlines inspection procedures.

2018-2022 BMW 840i

Resolution: Inspect differential mounting bolts for signs of corrosion. Clean corroded bolts, or replace if necessary, and ensure they are properly torqued upon installation.

Wheel Hub Nut Inspection Advisory

2023-01-10

Advisory to inspect the wheel hub nut for proper torque, and to replace the nut each time.

2018-2023 BMW 840i

Resolution: Inspect the wheel hub nut for proper torque and replace as needed.

About the Author

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Alan Montanye - Automotive Technical Specialist
ASE

Alan Montanye

Automotive Technical Specialist

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