BMW 340i 2019-present Drivetrain Bolt Torque Specifications & Fastener Values
BMW 340i 2019-present

BMW 340i 2019-present Drivetrain Bolt Torque Specifications

This page provides detailed torque specifications for drivetrain bolts on the 2019-Present BMW 340i (G20/G21) model. Includes torque values for the 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

Search Specifications

Search by component name, bolt size, or description

Torque Calculator

Convert between different torque units

Engine To Transmission

This section details the torque specifications for components connecting the engine to the transmission, including the flywheel/flexplate, and mounting bolts.

1

Flywheel Bolts (Manual Transmission)

M12 x 1.5
Torque Value
55 ft-lbs (75 N·m)
Important Notes
Ensure flywheel is properly aligned before tightening. Use new bolts if recommended by the service manual.
2

Flex Plate Bolts (Automatic Transmission)

M10 x 1.25
Important Notes
Tighten to the specified torque, then by an additional 90 degrees. Use new bolts.
3

Transmission Mounting Bolts

M12 x 1.75
Torque Value
50 ft-lbs (68 N·m)
Important Notes
Ensure the transmission is properly aligned and supported before tightening.
4

Torque Converter Bolts

M10 x 1.5
Torque Value
35 ft-lbs (47 N·m)
Important Notes
Ensure torque converter is fully seated to the flex plate. Use new bolts when possible.

Transmission

This section covers the torque specifications for various components within and attached to the transmission.

1

Transmission Oil Pan Bolts

M6 x 1.0
Torque Value
10 ft-lbs (14 N·m)
Important Notes
Tighten in a cross pattern to avoid warping the pan.
2

Transmission Drain and Fill Plugs

M18 x 1.5
Torque Value
20 ft-lbs (27 N·m)
Important Notes
Use new crush washers if recommended by the manual. Do not over-tighten to avoid damaging the threads.
3

Output Flange/Companion Flange Bolts

M10 x 1.5
Torque Value
50 ft-lbs (68 N·m)
Important Notes
These bolts secure the output flanges to the transmission where the driveshaft or axles bolt onto. Proper torque is necessary to prevent vibration and ensure joint integrity.

Drive Shaft

This section covers the torque specifications for the driveshaft and its associated components.

1

Propeller/Drive Shaft Bolts

M10 x 1.5
Torque Value
60 ft-lbs (81 N·m)
Important Notes
Ensure correct orientation of driveshaft to prevent vibration.

Rear Axle

This section includes torque specifications for the rear axle, differential, and associated components.

1

Drive Axle/Half Shaft Bolts

M10 x 1.5
Torque Value
85 ft-lbs (115 N·m)
Important Notes
Ensure proper seating of the axle before tightening.
2

CV Joint/Axle Nut

M24 x 1.5
Torque Value
185 ft-lbs (251 N·m)
Important Notes
Use a new nut if recommended by the service manual. Proper torque is crucial for wheel bearing preload.
3

Differential Mounting Bolts/Nuts

M14 x 2.0
Torque Value
60 ft-lbs (81 N·m)
Important Notes
Torque values may vary by location, consult service manual. Ensure proper differential alignment.
4

Differential Drain/Fill Plug

M16 x 1.5
Torque Value
30 ft-lbs (41 N·m)
Important Notes
Use a new crush washer if recommended by the manual.
5

Output Flange/Companion Flange Bolts (Differential)

M10 x 1.5
Torque Value
50 ft-lbs (68 N·m)
Important Notes
These bolts secure the output flange to the differential, ensure the flange is correctly aligned.

Transfer Case

This section contains the torque specifications for the transfer case found in xDrive (AWD) equipped vehicles.

1

Transfer Case Drain/Fill Plug

M16 x 1.5
Torque Value
25 ft-lbs (34 N·m)
Important Notes
Use a new crush washer if recommended by the manual.

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?

Using the correct torque ensures proper clamping force, preventing bolts from loosening due to vibration or stress. Over-tightening can damage threads or components, while under-tightening can lead to failure. For example, an under-torqued driveshaft bolt could vibrate loose, causing catastrophic drivetrain damage.

Q2

Where can I find the exact torque specifications for my specific 2019-Present BMW 340i drivetrain bolts?

The most reliable source is the official BMW repair manual for your specific model year. Reputable online resources dedicated to BMW repair can also provide this information, but always verify their accuracy. These specifications can vary slightly depending on the exact components installed and year, so always confirm prior to assembly. If in doubt, consult a trained and certified BMW technician.

Q3

Should I use new bolts when reassembling drivetrain components?

In many cases, yes. Many drivetrain bolts are designed as torque-to-yield (TTY) bolts, which stretch when tightened and should not be reused. Reusing TTY bolts can lead to improper clamping and potential failure. Examples include many driveshaft and axle bolts. Consult your repair manual to identify TTY bolts, which should ALWAYS be replaced.

Q4

What tools do I need to properly torque drivetrain bolts?

A calibrated torque wrench is essential. It allows you to apply the correct amount of force. Use appropriate sockets and extensions to reach bolts without damaging them or the surrounding components. Avoid using impact tools for final torque settings, instead use them to quickly install the hardware, and then finish using a torque wrench.

Q5

Can I use anti-seize or threadlocker on drivetrain bolts?

Follow the manufacturer's recommendations for each specific bolt. Generally, threadlocker is recommended for applications that are subject to vibration and prone to loosening. Anti-seize is typically not needed on most applications. Consult the repair manual for specific recommendations based on each individual fastener.

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 capable of measuring torque values in the 10-200 Nm range.

  • Precise torque measurement
  • Click-type mechanism
  • Reversible ratcheting head
Learn more

Torque Wrench (3/8" Drive)

A 3/8" drive torque wrench for smaller fasteners, capable of measuring torque values in the 5-50 Nm range.

  • Precise torque measurement
  • Click-type mechanism
  • Reversible ratcheting head
Learn more

Socket Set (Metric)

A comprehensive metric socket set, including shallow and deep sockets, in 1/2" and 3/8" drive sizes, specifically for use on BMW drivetrains.

  • 6-point sockets
  • Chrome Vanadium steel construction
  • Wide range of sizes (8mm-24mm)
Learn more

Universal Joint Adapter

A universal joint adapter (1/2" and 3/8" drive) for accessing fasteners at awkward angles.

  • Durable construction
  • Allows access to difficult fasteners
  • Swivel design
Learn more

Torque Angle Gauge

A torque angle gauge for fasteners that require both a torque value and an additional angle of rotation.

  • Accurate angle measurement
  • Easy to read dial
  • Adjustable arm
Learn more
Service Procedures

Driveshaft Bolt Torque Procedure

This procedure outlines how to correctly torque the driveshaft bolts on a 2019-Present BMW 340i.

  • Clean all bolt threads and mating surfaces.
  • Install driveshaft, ensuring proper alignment.
  • Tighten all bolts by hand to a snug fit.
  • Torque bolts to the specified first stage torque value using a torque wrench.
  • If required, apply the specified angle of rotation using a torque angle gauge.
  • Verify all bolts are correctly torqued.
View full procedure

Differential Mount Bolt Torque Procedure

This procedure details the proper way to torque the differential mounting bolts on a 2019-Present BMW 340i.

  • Clean all bolt threads and mating surfaces.
  • Install differential mounts, ensuring correct orientation.
  • Install bolts and tighten by hand to a snug fit.
  • Torque bolts to the specified first stage torque value using a torque wrench.
  • If required, apply the specified angle of rotation using a torque angle gauge.
  • Verify all bolts are correctly torqued.
View full procedure

Transmission Mounting Bolt Torque Procedure

This procedure details the proper way to torque the transmission mounting bolts on a 2019-Present BMW 340i.

  • Clean all bolt threads and mating surfaces.
  • Install transmission mounts, ensuring correct orientation.
  • Install bolts and tighten by hand to a snug fit.
  • Torque bolts to the specified first stage torque value using a torque wrench.
  • If required, apply the specified angle of rotation using a torque angle gauge.
  • Verify all bolts are correctly torqued.
View full procedure
Technical Service Bulletins

Driveshaft Bolt Loosening Issue

2021-05-15

Some 2019-2020 BMW 340i models have reported driveshaft bolt loosening. This is attributed to improper initial torque and incorrect fastening procedures.

2019-2020

Resolution: Inspect driveshaft bolts for any signs of loosening. Replace if necessary and follow the correct torque procedure, including any angle tightening required. Use new bolts and apply thread locker.

Differential Mounting Bolt Fatigue

2022-08-20

Certain instances of differential mounting bolt fatigue and cracking have been observed in 2020-2022 BMW 340i models with high mileage or performance modifications. This can cause premature wear and noises.

2020-2022

Resolution: Inspect differential mounting bolts for cracks, elongation or signs of fatigue. Replace with new bolts and re-torque to specification, following the correct tightening sequence. Consider using higher grade bolts for performance applications.

Transmission Mount Bolt Shear

2023-01-10

Cases of transmission mount bolt shear have been reported in 2021-2023 BMW 340i models that have experienced hard driving or high stress scenarios. This can cause excessive vibration and driveline damage.

2021-2023

Resolution: Inspect transmission mounting bolts for signs of shear or cracks. Replace with new, high-quality bolts and ensure proper torque and tightening sequence during reassembly. Consider using a thread locker for added security.

About the Author

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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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