Buick LaCrosse 2017-2019 Drivetrain Bolt Torque Specifications & Fastener Values
Buick LaCrosse 2017-2019

Buick LaCrosse 2017-2019 Drivetrain Bolt Torque Specifications

Detailed torque specifications for bolts related to the drivetrain components of the 2017-2019 Buick LaCrosse, including transmission, differential, and driveshaft.

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 connecting the flywheel to the crankshaft and the clutch assembly to the flywheel. Proper torque is crucial for power transfer and preventing vibration.

1

Flywheel Bolts

M10 x 1.5
Torque Value
46 ft-lbs (62 N·m)
Important Notes
Apply threadlocker to bolt threads. Torque in a star pattern.
2

Clutch Pressure Plate Bolts

M8 x 1.25
Torque Value
25 ft-lbs (34 N·m)
Important Notes
Torque in a star pattern to ensure even pressure distribution. This is an estimated value, verify with a service manual.

Transmission Mounting

Specifications for bolts mounting the transmission to the engine and vehicle frame, as well as case components. Proper torque is essential for alignment, vibration prevention, and leak prevention.

1

Transmission Mounting Bolts

M12 x 1.75
Torque Value
37 ft-lbs (50 N·m)
Important Notes
Ensure proper alignment before tightening. May require multiple torque passes.
2

Transmission Case Bolts

M8 x 1.25
Torque Value
20 ft-lbs (27 N·m)
Important Notes
Torque in a cross pattern. This is an estimated value, verify with a service manual.
3

Transmission Oil Pan Bolts

M6 x 1.0
Torque Value
8.8 ft-lbs (12 N·m)
Important Notes
Torque in a cross pattern to ensure even pressure distribution. Use a new gasket or sealant as needed.
4

Transmission Drain and Fill Plugs

M18 x 1.5
Torque Value
27 ft-lbs (37 N·m)
Important Notes
Use a new crush washer for proper sealing.

Driveshaft And Axles

Specifications for bolts connecting the driveshaft, axles, and CV joints. Correct torque is critical for power transfer, joint stability, and preventing vibration.

1

Drive Axle/Half Shaft Bolts

M10 x 1.5
Torque Value
118 ft-lbs (160 N·m)
Important Notes
Tighten all bolts evenly, alternating between bolts.
2

CV Joint/Axle Nut

M24 x 1.5
Torque Value
177 ft-lbs (240 N·m)
Important Notes
High torque is critical for proper wheel bearing preload. Use a new nut if specified.
3

Propeller/Drive Shaft Bolts

M10 x 1.5
Torque Value
30 ft-lbs (40 N·m)
Important Notes
Ensure proper alignment of the driveshaft before tightening. Torque in a cross pattern
4

Driveshaft Center Support Bearing Bolts

M10 x 1.5
Torque Value
35 ft-lbs (47 N·m)
Important Notes
Estimated torque value. Verify with a service manual. Tighten evenly.
5

Output Shaft Flange Bolts (Transmission & Differential)

M12 x 1.75
Torque Value
50 ft-lbs (68 N·m)
Important Notes
Estimated value, verify with a service manual. Tighten evenly.

Differential And Transfer Case

Specifications for bolts in the differential and transfer case, including drain/fill plugs. Proper torque is essential for preventing leaks and maintaining proper function.

1

Differential Ring Gear Bolts

M12 x 1.5
Important Notes
Tighten to the specified torque then turn an additional 90 degrees. Estimated torque, verify with the service manual.
2

Differential Drain/Fill Plug

M18 x 1.5
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Use a new crush washer for proper sealing.
3

Transfer Case Drain/Fill Plug

M18 x 1.5
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Use a new crush washer for proper sealing. Applies only to 4WD/AWD models.

Wheel Hub

Specifications for bolts securing the wheel hub and bearing assembly to the vehicle's knuckle. Though not directly drivetrain, these are critical to proper wheel function and safety.

1

Wheel Hub/Bearing Bolts

M12 x 1.75
Torque Value
118 ft-lbs (160 N·m)
Important Notes
Tighten all bolts evenly. Check for proper seating before final torque.

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 specifications ensures that bolts are tightened adequately to prevent loosening under stress and vibration, but not so tight that they become damaged or distort components. Improper torque can lead to drivetrain failures, premature wear, or even catastrophic accidents. For example, overtightening a CV axle nut could damage the bearing, while undertightening it could cause the axle to come loose while driving.

Q2

What happens if I overtighten a drivetrain bolt?

Overtightening can stretch or break the bolt, strip the threads in the receiving component, or crush the gasket/sealing surface. This can weaken the joint and lead to failure, and can be expensive to repair. A severely overtightened bolt on the driveshaft, for instance, might fail under load, causing loss of vehicle control.

Q3

What happens if I undertighten a drivetrain bolt?

Undertightening a bolt can allow movement and play at the connection, leading to increased stress, wear, and potential loosening over time. This could cause vibrations or noises, and ultimately component failure. For example, loose transmission mount bolts could cause excessive engine and transmission movement, damaging other components and impairing vehicle handling.

Q4

Should I use new bolts when working on the drivetrain?

Yes, it is highly recommended to use new bolts, especially torque-to-yield (TTY) bolts, whenever they are removed. These bolts are designed to stretch when torqued, and reusing them can result in inaccurate clamp loads. Many drivetrain components, such as the propeller shaft and differential, use TTY bolts.

Q5

Do I need any special tools for torquing drivetrain bolts?

Yes, you will need a calibrated torque wrench with the appropriate range and sockets to match the bolt sizes. For accurate results, the torque wrench should be within its calibration period. Also, it may be necessary to use jointed sockets or adapters to access certain bolts with clearance issues.

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 is essential for accurately tightening bolts to specified torque values.

  • Wide torque range (e.g., 20-250 ft-lbs)
  • Audible click when torque is reached
  • Accuracy within +/- 3%
Learn more

Torque Wrench (3/8" Drive)

A smaller torque wrench for lower torque applications, useful for smaller fasteners.

  • Lower torque range (e.g., 5-80 ft-lbs)
  • Audible click when torque is reached
  • Accuracy within +/- 3%
Learn more

Socket Set (Metric)

A comprehensive set of metric sockets is necessary to fit the various bolt heads on the drivetrain components.

  • Variety of sizes (e.g., 8mm - 24mm)
  • 6-point and 12-point options
  • Durable construction
Learn more

Socket Extensions

Extensions of various lengths are needed to reach recessed bolts and fasteners.

  • Various lengths (e.g., 3", 6", 10")
  • Durable construction
  • 1/2" and 3/8" drive options
Learn more

Universal Joint

A universal joint allows access to bolts located at angles.

  • 1/2" and 3/8" drive options
  • Durable construction
  • Wide range of motion
Learn more
Service Procedures

Driveshaft Bolt Torque Procedure

This procedure outlines how to properly torque the driveshaft bolts.

  • 1. Locate the driveshaft bolts connecting the driveshaft to the transmission and rear differential.
  • 2. Using the appropriate socket, hand-tighten all driveshaft bolts.
  • 3. Using a torque wrench set to 60 ft-lbs (81 Nm), torque each bolt in a star pattern.
  • 4. After torquing to 60 ft-lbs, tighten each bolt an additional 45 degrees.
  • 5. Verify all bolts are tightened to the correct torque and angle.
View full procedure

Transmission Mount Bolt Torque Procedure

This procedure explains the correct way to tighten transmission mount bolts.

  • 1. Locate all the transmission mount bolts securing the transmission to the frame.
  • 2. Hand-tighten all the transmission mount bolts.
  • 3. Torque the transmission mount bolts to 45 ft-lbs (61 Nm).
  • 4. If required by the specific mount, tighten an additional specified angle, as indicated in technical specifications.
  • 5. Re-check the torque on all bolts to ensure proper tightness.
View full procedure

Rear Differential Mount Bolt Torque Procedure

This procedure is to guide the tightening of the rear differential mount bolts.

  • 1. Locate all rear differential mount bolts securing the differential to the frame.
  • 2. Hand-tighten all the rear differential mount bolts.
  • 3. Torque the bolts to 65 ft-lbs (88 Nm).
  • 4. Verify all bolts are tightened to the correct torque.
  • 5. Inspect all mounts for correct alignment and positioning.
View full procedure

Axle Nut Torque Procedure

This procedure outlines the proper torqueing of the axle nuts.

  • 1. Locate the axle nuts at the wheel hubs.
  • 2. Ensure the vehicle's weight is on the wheels when torquing these nuts.
  • 3. Tighten the axle nut to 177 ft-lbs (240 Nm).
  • 4. Verify the torque on all axle nuts.
  • 5. After driving a short distance, re-check axle nut torque.
View full procedure
Technical Service Bulletins

Driveshaft Bolt Loosening Issue

2018-05-15

Some 2017-2018 LaCrosse models have experienced driveshaft bolt loosening. This may result in vibration or abnormal noise.

2017-2018

Resolution: Inspect and re-torque the driveshaft bolts per service procedure. If loosening reoccurs, use new bolts and proper thread locker.

Rear Differential Mounting Bolt Corrosion

2019-02-20

Certain vehicles operating in areas with heavy salt or corrosion may experience corrosion of the rear differential mount bolts.

2017-2019

Resolution: Inspect rear differential mounting bolts for corrosion. Replace as needed and apply anti-seize compound during re-installation. Re-torque to specifications.

Transmission Mount Bolt Creaking Noise

2017-12-10

Some 2017 models have reported creaking noise from transmission mounts. This issue has been attributed to insufficient torque on the transmission mounting bolts.

2017

Resolution: Inspect and re-torque transmission mount bolts using the specific procedure. Replace any excessively worn or deformed mounts.

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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