BMW 340i 2012-2018 Drivetrain Bolt Torque Specifications & Fastener Values
BMW 340i 2012-2018

BMW 340i 2012-2018 Drivetrain Bolt Torque Specifications

Comprehensive guide to drivetrain bolt torque specifications for the 2012-2018 BMW 340i (F30) model, including transmission, differential, driveshaft, and related 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 Flywheel

Specifications for bolts securing the flywheel (manual transmission) or flexplate (automatic transmission) to the crankshaft. Proper torque is crucial for balanced power transfer.

1

Flywheel Bolts (Manual Transmission)

M12 x 1.5
Torque Value
55 ft-lbs (75 N·m)
Important Notes
These bolts are often Torque-to-Yield (TTY) and should be replaced upon removal. Ensure surfaces are clean and free of debris. Apply a light coat of threadlocker if recommended by the service manual.
2

Flex Plate Bolts (Automatic Transmission)

M12 x 1.5
Torque Value
55 ft-lbs (75 N·m)
Important Notes
These bolts are often Torque-to-Yield (TTY) and should be replaced upon removal. Ensure surfaces are clean and free of debris. Apply a light coat of threadlocker if recommended by the service manual.

Clutch Components

Specifications for bolts related to the clutch system in manual transmission vehicles. Proper torque is critical for clutch engagement and release.

1

Clutch Pressure Plate Bolts

M8 x 1.25
Torque Value
20 ft-lbs (27 N·m)
Important Notes
Tighten bolts in a star pattern. Ensure the pressure plate is properly aligned with the flywheel before tightening. Use a calibrated torque wrench.
2

Clutch Slave Cylinder Bolts

M6 x 1.0
Torque Value
15 ft-lbs (20 N·m)
Important Notes
Ensure the slave cylinder is properly seated before tightening. Do not overtighten as this could damage the cylinder or threads. Use a calibrated torque wrench.

Transmission

Specifications for bolts related to the transmission assembly, including mounting to the engine/chassis and case bolts.

1

Transmission Mounting Bolts

M12 x 1.75
Torque Value
37 ft-lbs (50 N·m)
Important Notes
Ensure transmission is properly aligned before tightening these bolts. Use a calibrated torque wrench. Apply threadlocker if recommended by service manual
2

Transmission Oil Pan Bolts

M6 x 1.0
Torque Value
7.4 ft-lbs (10 N·m)
Important Notes
Tighten bolts in a star pattern to ensure even seal compression. Do not overtighten as this could damage the pan or threads.
3

Transmission Case Bolts

M10 x 1.5
Torque Value
30 ft-lbs (40 N·m)
Important Notes
Tighten bolts in a cross pattern to ensure even seal compression. Apply threadlocker if recommended by service manual.

Transmission Service

Specifications for transmission drain and fill plugs. Proper torque prevents leaks and allows for easy future service.

1

Transmission Drain and Fill Plugs

M18 x 1.5
Torque Value
30 ft-lbs (40 N·m)
Important Notes
Use a new sealing washer each time. Do not overtighten as this could damage the threads.

Driveshaft

Specifications for bolts related to the driveshaft (propeller shaft). Proper torque is critical for minimizing vibrations and ensuring reliable power transfer.

1

Propeller/Drive Shaft Bolts (Transmission & Differential Flanges)

M10 x 1.5
Torque Value
59 ft-lbs (80 N·m)
Important Notes
Ensure proper driveshaft alignment before tightening. Apply threadlocker if recommended by service manual.
2

Driveshaft Center Support Bearing Bolts

M8 x 1.25
Torque Value
22 ft-lbs (30 N·m)
Important Notes
Ensure bearing is properly aligned before tightening. Do not overtighten. Apply threadlocker if recommended by service manual.

Differential

Specifications for bolts related to the differential unit, including output flanges and service plugs.

1

Differential Output Flange Bolts (to Driveshaft/Axle)

M10 x 1.5
Torque Value
59 ft-lbs (80 N·m)
Important Notes
These are often the same specification as the driveshaft bolts. Ensure proper flange alignment before tightening. Apply threadlocker if recommended by service manual.
2

Differential Drain/Fill Plug

M18 x 1.5
Torque Value
37 ft-lbs (50 N·m)
Important Notes
Use a new sealing washer each time. Do not overtighten as this could damage the threads.

Transfer Case

Specifications for transfer case drain and fill plugs (for All-Wheel-Drive models). Proper torque prevents leaks and allows for easy future service.

1

Transfer Case Drain/Fill Plug

M18 x 1.5
Torque Value
37 ft-lbs (50 N·m)
Important Notes
Use a new sealing washer each time. Do not overtighten as this could damage the threads.

Drive Axle

Specifications for bolts and nuts associated with drive axles/half shafts, including attachment to the transmission/differential and wheel hub. Proper torque is vital for joint and shaft reliability.

1

Drive Axle/Half Shaft Bolts (Transmission/Differential Side)

M10 x 1.5
Torque Value
65 ft-lbs (88 N·m)
Important Notes
Ensure proper alignment before tightening. Apply threadlocker if recommended by the service manual.
2

CV Joint/Axle Nut (Wheel Hub Side)

M24 x 1.5
Torque Value
214 ft-lbs (290 N·m)
Important Notes
This nut is often Torque-to-Yield (TTY) and should be replaced upon removal. Ensure proper wheel bearing preload and axle joint integrity. Use a calibrated torque wrench.

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 using the correct torque specification important for drivetrain bolts?

Using the correct torque specification is crucial for several reasons. Overtightening can stretch or break bolts, causing component failure or damage to the threads in the housings. Undertightening can lead to bolts loosening over time, causing vibrations, leaks, or eventual failure. Correct torque ensures proper clamping force, maintaining the integrity and safety of the drivetrain.

Q2

What happens if I overtighten a drivetrain bolt?

Overtightening a drivetrain bolt can cause several problems. The bolt itself may stretch beyond its yield point, leading to permanent deformation and a reduction in its clamping force. In some cases, the bolt can break or the threads in the component it's being fastened to can be stripped. This can be expensive to repair and can also create a dangerous situation. Imagine overtightening the driveshaft bolts; they may fail, leading to a catastrophic loss of control while driving.

Q3

Can I reuse drivetrain bolts, or should they be replaced?

It's best practice to replace certain drivetrain bolts, especially those that are torque-to-yield (TTY) bolts or have been previously torqued to a high value. These bolts are designed to stretch upon installation and may not provide the same clamping force if reused. For example, bolts securing the transmission to the engine or the rear differential to the chassis are often recommended to be replaced. Check your vehicle's repair manual or TIS documentation for specific bolt replacement guidelines.

Q4

What tools do I need to correctly torque drivetrain bolts?

You will need a calibrated torque wrench that covers the range of specified torque values for your vehicle. Additionally, you will often need a variety of sockets and extensions to access the bolts properly. A torque angle gauge may also be necessary for torque-to-yield bolts. Ensure the torque wrench is calibrated regularly for accurate readings. Do NOT use an impact gun to tighten or loosen, only to remove the bolt. Proper technique is crucial for accurate torque application.

Q5

Where can I find the exact torque specifications for my 2012-2018 BMW 340i drivetrain?

The most reliable source for exact torque specifications is your vehicle's repair manual or the BMW Technical Information System (TIS). Online forums and resources can be helpful, but always confirm with the official sources. Ensure you are using the correct information specific to your car's model and transmission.

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 larger bolts on the drivetrain to their specified torque.

  • Wide torque range suitable for drivetrain components
  • Click-type mechanism for accurate readings
  • Durable construction for repeated use
Learn more

Torque Wrench (3/8" Drive)

A 3/8" drive torque wrench is useful for smaller drivetrain bolts and fasteners that require lower torque settings.

  • Lower torque range for smaller bolts
  • Compact design for tight spaces
  • Click-type mechanism for accurate readings
Learn more

Socket Set (1/2" and 3/8" Drive)

A comprehensive socket set with both 1/2" and 3/8" drive sockets is needed to fit all bolt head sizes on the drivetrain.

  • Variety of socket sizes, both metric and standard
  • Durable chrome vanadium steel construction
  • Includes deep and standard sockets
Learn more

Extension Bars (1/2" and 3/8" Drive)

Extension bars of various lengths are helpful for reaching recessed bolts and fasteners on the drivetrain.

  • Various lengths to improve reach
  • Durable construction
  • Secure locking mechanism to prevent wobbling
Learn more

Universal Joint Adapters (1/2" and 3/8" Drive)

Universal joint adapters allow for access to bolts and fasteners at awkward angles.

  • Provides flexibility for angle applications
  • Durable construction
  • Smooth operation
Learn more
Service Procedures

Driveshaft to Differential Flange Bolt Torque

This procedure outlines the tightening of bolts connecting the driveshaft to the differential flange.

  • Locate the driveshaft to differential flange bolts.
  • Apply specified torque to each bolt in a star pattern to ensure even clamping.
  • Double-check the torque on all bolts.
View full procedure

Differential Mounting Bolt Torque

This procedure covers the torque specifications for the bolts securing the differential to the chassis.

  • Locate the differential mounting bolts.
  • Tighten bolts to the specified initial torque in a cross pattern.
  • Tighten bolts to the final torque in the same cross pattern.
View full procedure

Transmission Mount Bolt Torque

This procedure details the tightening sequence for the bolts that secure the transmission mount.

  • Locate the transmission mount bolts.
  • Tighten all bolts to the specified torque using a proper torque wrench
  • Double check torque values after initial torque
View full procedure

Wheel Hub Bolt Torque

This procedure covers the correct torque settings for tightening the wheel hub bolts.

  • Locate the wheel hub bolts
  • Using a cross pattern, tighten bolts to the correct torque specification
  • Double-check the torque on all bolts
View full procedure
Technical Service Bulletins

Incorrect Driveshaft Bolt Torque May Cause Vibration

2016-05-12

Incorrect torque of the driveshaft bolts to the differential flange can lead to premature wear and vibrations at speed. This bulletin provides the correct torque and tightening procedure.

2012-2016 BMW 340i

Resolution: Ensure driveshaft bolts are torqued to 64nm + 90 degrees. Always replace bolts when removed.

Differential Mounting Bolt Loosening

2017-11-20

Some vehicles have exhibited loose differential mounting bolts. This bulletin updates torque specifications and tightening sequence.

2016-2018 BMW 340i

Resolution: Use a torque wrench to tighten the differential mounting bolts to the updated specification of 80nm + 90 degrees. Always replace bolts when removed.

Transmission Mounting Bolt Fatigue

2018-03-15

Some transmission mounts have shown signs of loosening due to improper torqueing. This bulletin covers the correct torqueing sequence and bolt type.

2017-2018 BMW 340i

Resolution: Tighten transmission mounting bolts to 56nm + 60 degrees. Always replace bolts when removed.

About the Author

Expert automotive knowledge and experience

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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