BMW 335i 2012-2018 Drivetrain Bolt Torque Specifications & Fastener Values
BMW 335i 2012-2018

BMW 335i 2012-2018 Drivetrain Bolt Torque Specifications

Detailed torque specifications for drivetrain bolts on the 2012-2018 BMW 335i (F30, F31, F34) models. Includes transmission, differential, driveshaft, and axle bolt torque values.

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 components related to the engine flywheel and clutch assembly, responsible for transmitting power from the engine to the transmission.

1

Flywheel Bolts

M12 x 1.5
Torque Value
63 ft-lbs (85 N·m)
Important Notes
Tighten in a star pattern in multiple passes. Always use new bolts.
2

Clutch Pressure Plate Bolts

M8 x 1.25
Torque Value
20 ft-lbs (27 N·m)
Important Notes
Tighten in a star pattern in multiple passes.

Transmission

Specifications for bolts related to the transmission housing, mounting, and fluid maintenance.

1

Transmission Mounting Bolts

M12 x 1.75
Torque Value
35 ft-lbs (47 N·m)
Important Notes
Tighten evenly, ensuring transmission is properly aligned.
2

Transmission Oil Pan Bolts

M6 x 1.0
Torque Value
9 ft-lbs (12 N·m)
Important Notes
Tighten in a criss-cross pattern. Do not over-tighten to avoid damaging the pan.
3

Transmission Drain and Fill Plugs

M22 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
Use new sealing washer. Do not over-tighten to avoid stripping threads.

Propeller Shaft

Specifications for the propeller shaft assembly, including mounting points, flex disc, and center support bearing.

1

Propeller Shaft Bolts (to Transmission and Differential Flanges)

M10 x 1.5
Torque Value
18 ft-lbs (24 N·m)
Important Notes
Ensure proper alignment during installation. Use new bolts when possible.
2

Guibo/Flex Disc Bolts

M10 x 1.5
Torque Value
18 ft-lbs (24 N·m)
Important Notes
Use new bolts. Tighten evenly to ensure proper disc alignment.
3

Center Support Bearing Bolts

M8 x 1.25
Torque Value
20 ft-lbs (27 N·m)
Important Notes
Ensure bearing is properly aligned before tightening.

Differential

Specifications for bolts related to the differential housing, input/output flanges, and fluid maintenance.

1

Differential Input Flange Bolt

M10 x 1.5
Torque Value
65 ft-lbs (88 N·m)
Important Notes
Torque evenly to ensure the proper contact between flanges.
2

Differential Output Flange Bolts

M10 x 1.5
Torque Value
65 ft-lbs (88 N·m)
Important Notes
Torque evenly to ensure proper contact between flanges.
3

Differential Drain and Fill Plugs

M18 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
Use new sealing washer. Do not over-tighten to avoid stripping threads.

Drive Axles

Specifications for bolts securing the drive axles to the transmission/differential and wheel hubs.

1

Drive Axle/Half Shaft Bolts (to Differential or Transmission Flange)

M10 x 1.5
Torque Value
70 ft-lbs (95 N·m)
Important Notes
Ensure proper alignment of the axle and flange.
2

CV Joint/Axle Nut

M24 x 1.5
Torque Value
195 ft-lbs (265 N·m)
Important Notes
Use new nut. This is a critical component for wheel bearing preload.

Transfer Case

Specifications for components related to the transfer case system for all-wheel drive vehicles.

1

Transfer Case Mounting Bolts

M12 x 1.75
Torque Value
35 ft-lbs (47 N·m)
Important Notes
Tighten evenly, ensuring transfer case is properly aligned.
2

Transfer Case Drain and Fill Plugs

M18 x 1.5
Torque Value
25 ft-lbs (34 N·m)
Important Notes
Use new sealing washer. Do not over-tighten to avoid stripping threads.

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 preventing component failure, maintaining proper clamping force, and ensuring the longevity of your BMW's drivetrain. Over-tightening can lead to bolt stretching or fracture, while under-tightening can cause parts to loosen, leading to vibrations, wear, and potential catastrophic failure. Imagine a driveshaft bolt coming loose mid-drive, the consequences could be severe.

Q2

What happens if I over-torque a driveshaft bolt?

Over-torquing a driveshaft bolt can lead to several problems. First, the bolt itself could yield and permanently stretch, weakening it and making it more prone to failure later. Second, it can deform the mating surfaces on the driveshaft flange or transmission output, potentially leading to imbalance and vibration. In a worse case scenario, an overtorqued bolt might snap entirely while driving. For example, overtightening the flex disc bolts could result in early failure.

Q3

Do I need to replace bolts after removing them, specifically for the drivetrain?

Yes, many drivetrain bolts, particularly those subjected to high stress and torque, are designed to be 'torque-to-yield' (TTY) or 'stretch' bolts. These bolts are designed to stretch when tightened and should always be replaced after removal. Failing to replace these bolts risks losing clamping force, potential loosening, and eventual failure. For example, driveshaft bolts and certain differential bolts are typically TTY and need replacing every time. Always consult the BMW repair manual for your specific model.

Q4

What tools do I need to properly torque drivetrain bolts?

You will need a calibrated torque wrench that covers the range of specified torques for the bolts you are working with. It is critical to have a torque wrench with a range covering what is needed, for example, most transmission bolts will need higher torque than flex disc bolts. A variety of sockets and extensions to reach the bolts are also needed. Using an impact wrench instead of hand torquing could easily result in over torquing, leading to potential damage.

Q5

How often should I check the torque on my drivetrain bolts?

Typically, it is not necessary to routinely check the torque of drivetrain bolts unless you have recently performed maintenance or repairs. However, if you experience new vibrations, clunking noises, or have had any impact to the drivetrain area, it's a good idea to check the torque on relevant components. For instance, after replacing a driveshaft, checking the bolt torque after 50-100 miles is advisable.

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 calibrated torque wrench for applying accurate torque to fasteners. Essential for drivetrain components.

  • Wide torque range (e.g., 20-200 ft-lbs)
  • Click-type or digital readout
  • Accurate calibration
Learn more

Torque Wrench (3/8" Drive)

A smaller torque wrench for lower torque applications in the drivetrain, specifically with smaller fasteners and tight spaces.

  • Torque range (e.g., 5-80 ft-lbs)
  • Click-type or digital readout
  • Compact design for tight spaces
Learn more

Socket Set (Metric)

A comprehensive set of metric sockets in various sizes to fit the bolts and nuts used in the drivetrain system.

  • Standard and deep sockets
  • Sizes ranging from 8mm to 24mm
  • Durable chrome vanadium steel construction
Learn more

Extension Bars

Used to extend reach to fasteners in recessed areas of the drivetrain.

  • Various lengths for different needs
  • Durable steel construction
  • 1/2" and 3/8" drive options
Learn more

Universal Joint

Allows for torque application at an angle when a straight line approach is not possible.

  • 1/2" and 3/8" drive options
  • Durable steel construction
  • Smooth rotation
Learn more
Service Procedures

Driveshaft Bolt Torque Procedure

Proper procedure for tightening driveshaft bolts to the specified torque to ensure proper driveline operation.

  • Locate driveshaft bolts at the transmission and differential flanges.
  • Apply a drop of medium strength thread locker to each bolt.
  • Use the correct size socket and torque wrench.
  • Tighten bolts to the specified torque in a star pattern for even distribution.
  • Double check all torqued bolts
View full procedure

Differential Mounting Bolt Torque Procedure

Proper procedure for tightening differential mounting bolts to the specified torque to ensure secure and stable mounting.

  • Locate the differential mounting bolts securing it to the subframe.
  • Clean the bolt threads of any dirt or debris.
  • Tighten bolts to the specified torque using the correct size socket and torque wrench.
  • Tighten using a star pattern to ensure even pressure
  • Double check the torque on all bolts
View full procedure

Transmission Mounting Bolt Torque Procedure

Proper procedure for tightening transmission mounting bolts to the specified torque to ensure secure and stable mounting.

  • Locate the transmission mounting bolts that secure it to the engine or chassis.
  • Clean the bolt threads of any dirt or debris.
  • Tighten bolts to the specified torque using the correct size socket and torque wrench.
  • Tighten using a star pattern to ensure even pressure
  • Double check the torque on all bolts
View full procedure
Technical Service Bulletins

Excessive Vibration Due to Incorrect Driveshaft Bolt Torque

2016-03-15

Reports of excessive vibration or driveline noise on 2012-2016 335i models due to incorrect driveshaft bolt torque after service.

2012-2016 BMW 335i

Resolution: Inspect driveshaft bolts and re-torque to specification (64 Nm + 90 Degrees). Replace bolts if stretched or damaged.

Differential Mounting Bolt Loosening Issue

2017-09-22

A small number of differential mounting bolts have been reported to loosen due to incorrect torque or improper thread locking causing noise or play in the driveline on 2015-2018 BMW 335i models.

2015-2018 BMW 335i

Resolution: Inspect differential mounting bolts. Remove bolts and clean threads. Apply new medium strength thread locker and torque bolts to specification (68 Nm). Inspect after 1000km for proper torque retention.

About the Author

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Alan Montanye - Automotive Technical Specialist
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Alan Montanye

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