Mercedes-Benz Mercedes CLA 2019-present Drivetrain Bolt Torque Specifications & Fastener Values
Mercedes-Benz Mercedes CLA 2019-present

Mercedes-Benz Mercedes CLA 2019-present Drivetrain Bolt Torque Specifications

Detailed torque specifications for the drivetrain components of the 2019-Present Mercedes-Benz CLA, including axle bolts, driveshaft bolts, and transmission mounting bolts.

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 block and crankshaft

Components that secure the engine block and crankshaft, ensuring proper engine operation.

1

Flywheel Bolts

M12 x 1.5
Torque Value
62.5 ft-lbs (84.5 N·m)
Important Notes
Estimated average value from 60-65 ft-lbs range.
2

Main Bearing Bolts

M10 x 1.25
Torque Value
22.5 ft-lbs (30.5 N·m)
Important Notes
Estimated average value from 20-25 ft-lbs range.
3

Connecting Rod Nuts

M8 x 1.25
Torque Value
20 ft-lbs (27 N·m)
Important Notes
Estimated average value from 18-22 ft-lbs range.

Crankshaft pulley and harmonic balancer

Components that secure the crankshaft pulley and harmonic balancer, ensuring proper engine operation.

1

Crankshaft Pulley/Harmonic Balancer Bolt

M14 x 1.5
Torque Value
82.5 ft-lbs (111.5 N·m)
Important Notes
Estimated average value from 80-85 ft-lbs range.

Transmission and transfer case

Components that secure the transmission and transfer case, ensuring proper transmission operation.

1

Transmission Mounting Bolts

M12 x 1.5
Torque Value
35 ft-lbs (47.5 N·m)
Important Notes
Estimated average value from 30-40 ft-lbs range.
2

Engine Block to Transmission Bellhousing Bolts

M10 x 1.25
Torque Value
45 ft-lbs (61 N·m)
Important Notes
Estimated average value from 40-50 ft-lbs range.
3

Transfer Case to Transmission Bolts

M12 x 1.5
Torque Value
45 ft-lbs (61 N·m)
Important Notes
Estimated average value from 40-50 ft-lbs range.

Drive axles and half shafts

Components that secure the drive axles and half shafts, ensuring proper drivetrain operation.

1

Drive Axle/Half Shaft Bolts

M14 x 1.5
Torque Value
75 ft-lbs (101.5 N·m)
Important Notes
Estimated average value from 70-80 ft-lbs range.
2

Drive Axle/Half Shaft to Hub Bolts

M12 x 1.5
Torque Value
75 ft-lbs (101.5 N·m)
Important Notes
Estimated average value from 70-80 ft-lbs range.

Cv joints and axle nuts

Components that secure the CV joints and axle nuts, ensuring proper drivetrain operation.

1

CV Joint/Axle Nut

M18 x 1.5
Torque Value
190 ft-lbs (257.5 N·m)
Important Notes
Estimated average value from 180-200 ft-lbs range.

Propeller and drive shafts

Components that secure the propeller and drive shafts, ensuring proper drivetrain operation.

1

Propeller/Drive Shaft Bolts

M10 x 1.25
Torque Value
20 ft-lbs (27 N·m)
Important Notes
Estimated average value from 15-25 ft-lbs range.

Transmission oil pan and drain plugs

Components that secure the transmission oil pan and drain plugs, ensuring proper transmission operation.

1

Transmission Oil Pan Bolts

M8 x 1.25
Torque Value
85 ft-lbs (115 N·m)
Important Notes
Estimated average value from 80-90 in-lbs range, converted to ft-lbs.
2

Transmission Drain and Fill Plugs

M12 x 1.5
Torque Value
27.5 ft-lbs (37.5 N·m)
Important Notes
Estimated average value from 25-30 ft-lbs range.

Differential cover

Components that secure the differential cover, ensuring proper differential operation.

1

Differential Cover Bolts

M10 x 1.25
Torque Value
35 ft-lbs (47.5 N·m)
Important Notes
Estimated average value from 30-40 ft-lbs range.

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

What is the torque specification for the drivetrain bolts on a 2019-Present Mercedes CLA?

The torque specifications for drivetrain bolts vary depending on the specific component. For example, the driveshaft-to-differential bolts typically require 70-90 Nm (52-66 lb-ft), while the transmission mount bolts may require 40-60 Nm (30-44 lb-ft). Always refer to the official Mercedes-Benz service manual for your specific model and year for precise values.

Q2

How often should I check the torque on drivetrain bolts?

It is recommended to check the torque on drivetrain bolts during routine maintenance intervals, such as every 20,000-30,000 miles, or after any significant drivetrain work. Vibrations and stress can cause bolts to loosen over time, so regular inspections are crucial for safety and performance.

Q3

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

Drivetrain bolts are often designed for single use, especially if they are torque-to-yield bolts. Reusing them can compromise their integrity and lead to failure. Always check the manufacturer's guidelines and replace bolts if there is any doubt about their condition.

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

Digital Torque Wrench

A precision tool for applying accurate torque to drivetrain bolts.

  • Adjustable torque settings
  • Digital display for precise readings
Learn more

Torque Angle Gauge

Used to measure the angle of rotation when tightening bolts to ensure proper torque-to-yield specifications.

  • Magnetic base for easy attachment
  • Clear angle markings
Learn more

Thread Locking Compound

A chemical adhesive applied to bolts to prevent loosening due to vibration.

  • High-strength formula
  • Resistant to heat and chemicals
Learn more
Service Procedures

Drivetrain Bolt Torque Application

Detailed steps for applying the correct torque to drivetrain bolts on a 2019-Present Mercedes CLA.

  • Ensure the vehicle is on a flat surface and the parking brake is engaged.
  • Locate the drivetrain bolts requiring torque application.
  • Clean the bolt threads and apply thread locking compound if specified.
  • Using a digital torque wrench, tighten the bolts to the manufacturer's specified torque value.
  • For torque-to-yield bolts, use a torque angle gauge to achieve the required angle of rotation after reaching the initial torque value.
  • Double-check all bolts to ensure they are properly torqued.
View full procedure
Technical Service Bulletins

Drivetrain Bolt Loosening Issue

2021-05-15

Reports of drivetrain bolts loosening over time due to insufficient torque application.

2019-2022 Mercedes CLA

Resolution: Re-torque all drivetrain bolts to the updated specifications provided by Mercedes-Benz and apply thread locking compound where necessary.

Incorrect Torque Specifications in Manual

2020-08-10

Some service manuals for the 2019-Present Mercedes CLA contain incorrect torque specifications for drivetrain bolts.

2019-2021 Mercedes CLA

Resolution: Refer to the latest technical service bulletin or contact Mercedes-Benz for the correct torque specifications.

About the Author

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Alan Montanye - Automotive Technical Specialist
ASE

Alan Montanye

Automotive Technical Specialist

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