BMW 840i 2018-present Suspension Bolt Torque Specifications
This page provides detailed torque specifications for all suspension bolts on the 2018-Present BMW 840i, including front and rear suspension components. Ensure proper tightening for safe and optimal vehicle handling.
Important Information
Safety guidelines and reference information for proper torque application
Safety First
- Always verify torque specifications with your vehicle's factory service manual
- Use properly calibrated torque wrenches
- Replace all torque-to-yield (TTY) bolts - they are single-use only
- When in doubt, consult a professional mechanic
Quick Reference Guide
Quick Reference Guide
Common Torque Patterns
Star Pattern
Used for wheels and other circular bolt patterns
Cross Pattern
Used for gaskets and cover plates
Sequential Pattern
Used for head bolts and other critical components
Common Mistakes to Avoid
Common Mistakes to Avoid
Over-tightening
Exceeding the specified torque value can stretch or break fasteners, damage threads, or crack components.
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.
Follow the manufacturer's specified torque sequence pattern.
Dirty Threads
Dirt, rust, or old thread locker can affect torque readings and proper fastener tension.
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.
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.
Check if specs are for dry or lubricated threads. Use specified lubricant when required.
Recommended Tools
Recommended Tools
Torque Wrench (1/4" Drive)
Torque Wrench (3/8" Drive)
Torque Wrench (1/2" Drive)
Angle Gauge
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
Strut Shock Absorber
Torque specifications for components related to the strut/shock absorber assembly, including mounting to the chassis and top mounts.
1 Strut/Shock Absorber Lower Mounting Bolts
M12 x 1.5
Strut/Shock Absorber Lower Mounting Bolts
M12 x 1.5Torque Value
Important Notes
2 Strut Top Mount Bolts
M8 x 1.25
Strut Top Mount Bolts
M8 x 1.25Torque Value
Important Notes
Control Arms
Torque specifications for control arm bolts and connections to the chassis and steering knuckle.
1 Control Arm Bolts (Chassis Side)
M14 x 1.5
Control Arm Bolts (Chassis Side)
M14 x 1.5Torque Value
Important Notes
2 Steering Knuckle To Lower Control Arm Bolt
M14 x 1.5
Steering Knuckle To Lower Control Arm Bolt
M14 x 1.5Important Notes
Steering Components
Torque specifications for ball joints, tie rod ends, and related steering components.
1 Ball Joint Nut
M12 x 1.25
Ball Joint Nut
M12 x 1.25Torque Value
Important Notes
2 Tie Rod End Nut
M10 x 1.25
Tie Rod End Nut
M10 x 1.25Torque Value
Important Notes
Sway Bar
Torque specifications for sway bar links and mounting bracket components.
1 Sway Bar Link Nut
M10 x 1.5
Sway Bar Link Nut
M10 x 1.5Torque Value
Important Notes
2 Sway Bar Bushing Bracket Bolts
M8 x 1.25
Sway Bar Bushing Bracket Bolts
M8 x 1.25Torque Value
Important Notes
Brake System
Torque specifications for brake caliper and mounting bracket bolts as they are attached to the steering knuckle.
1 Brake Caliper Bolts
M12 x 1.75
Brake Caliper Bolts
M12 x 1.75Torque Value
Important Notes
2 Brake Caliper Mounting Bracket Bolts
M12 x 1.75
Brake Caliper Mounting Bracket Bolts
M12 x 1.75Torque Value
Important Notes
Wheel Speed Sensor
Torque specifications for the wheel speed sensor mounting to the steering knuckle.
1 Wheel Speed Sensor Mounting Bolt/Screw
M6 x 1.0
Wheel Speed Sensor Mounting Bolt/Screw
M6 x 1.0Torque Value
Important Notes
Troubleshooting Guide
Common issues, diagnostic steps, and prevention guidelines
Common Issues
Bolt stretching, stripped threads, uneven torque patterns
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
Diagnostic Steps
Visual inspection, torque verification, thread assessment
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
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
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
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 suspension bolts?
Why is using the correct torque specification important for suspension bolts?
Using the correct torque specification ensures proper clamping force. Under-torqued bolts can loosen, leading to suspension instability and potential failure. Over-torqued bolts can stretch or break, damaging components and also causing failure. Proper torque is critical for both performance and safety. For example, a loose control arm bolt could cause dangerous handling issues at speed, or the bolt could shear, leading to sudden loss of control.
Q2 What happens if I don't have a torque wrench?
What happens if I don't have a torque wrench?
While it's strongly recommended to use a torque wrench, you should NEVER attempt to use guesswork. If you don't have one, tighten the bolt with a hand wrench just until it is snug, and then seek professional help immediately for proper tightening. Using a torque wrench is the safest and most accurate way to achieve the correct fastener tension. Always recheck torque after a short test drive to ensure the fasteners haven't loosened.
Q3 Should I use new bolts when working on the suspension?
Should I use new bolts when working on the suspension?
It is generally recommended to use new bolts whenever disassembling the suspension. Many suspension bolts are torque-to-yield (TTY), meaning they stretch when torqued and are designed for single use. Reusing these bolts can lead to improper clamping force and failure. Always consult the official BMW repair manual for specific fastener replacement guidelines. Example: reused strut bolts can fail at high speed, endangering the driver.
Q4 What is the difference between Nm (Newton-meters) and lb-ft (foot-pounds) for torque?
What is the difference between Nm (Newton-meters) and lb-ft (foot-pounds) for torque?
Nm (Newton-meters) and lb-ft (foot-pounds) are both units of torque. Nm is the metric unit, and lb-ft is the imperial unit. You will need to know the correct unit when using your torque wrench. The manufacturer provides all specifications in both, and it's essential to use the correct unit to avoid errors. For example, using an lb-ft torque value when you should have used Nm could result in significantly over or under tightened bolts.
Environmental Considerations
Temperature, humidity, and seasonal effects on torque specifications
Temperature Effects
Includes: High Heat, Cold Weather, Thermal Cycling
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
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
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 tightening bolts to the correct specification. A 1/2" drive is recommended for most suspension components.
- Wide torque range (e.g., 20-200 Nm)
- Click-type mechanism for accuracy
- Reversible ratcheting head
Torque Wrench (3/8" Drive)
A smaller torque wrench is needed for lower torque fasteners in the suspension system. A 3/8" drive is helpful for smaller fasteners and harder to reach areas.
- Smaller torque range (e.g., 5-60 Nm)
- Click-type mechanism for accuracy
- Reversible ratcheting head
Socket Set (Metric)
A comprehensive set of metric sockets is required to fit various bolt and nut sizes on the BMW 840i suspension.
- Sizes ranging from 8mm to 24mm
- 6-point sockets for better grip
- Variety of depths and extensions
Wrench Set (Metric)
A metric wrench set is helpful to hold fasteners when tightening nuts, especially those that require two wrenches.
- Sizes matching socket set (8-24mm)
- Open-end and Box-end options
- Durable construction
Allen/Hex Key Set
Some suspension components use hex head fasteners. A metric hex key set is needed to tighten and loosen these.
- Sizes from 2.5mm to 10mm
- Ball-end options for angled access
- Durable construction
Extension Bars
Extension bars in various lengths are required to reach recessed bolts, especially in the suspension.
- 3", 6", and 10" lengths
- Various drive sizes to match wrenches
- Durable construction
Service Procedures
Front Strut/Shock Absorber Replacement
This procedure outlines the steps to replace the front strut/shock absorber including critical torque specifications.
- Loosen the wheel lugs and lift the vehicle safely.
- Remove the wheel.
- Disconnect the suspension sensor if equipped.
- Support the suspension control arm with a jack.
- Loosen the strut to hub pinch bolt.
- Disconnect the stabilizer bar link.
- Remove the upper strut mount bolts.
- Lower the control arm jack and carefully remove the strut assembly.
- Install new components, torquing the upper strut mounts to 22Nm
- Torque the Strut to Hub pinch bolt to 110Nm + 90 degrees
- Torque the wheel lugs to 140Nm
- Recheck torque settings after 50-100 miles
Rear Shock Absorber Replacement
This procedure outlines the steps to replace the rear shock absorber including critical torque specifications.
- Loosen the wheel lugs and lift the vehicle safely.
- Remove the wheel.
- Disconnect the suspension sensor if equipped.
- Support the rear control arm with a jack.
- Remove the lower shock mounting bolt.
- Remove the upper shock mounting bolts.
- Carefully remove the shock absorber assembly.
- Install new components, torquing the upper mounts to 22Nm.
- Torque the lower shock mounting bolt to 110Nm + 90 degrees.
- Torque the wheel lugs to 140Nm
- Recheck torque settings after 50-100 miles
Front Control Arm Replacement
This procedure outlines the steps to replace the front control arm including critical torque specifications.
- Loosen the wheel lugs and lift the vehicle safely.
- Remove the wheel.
- Support the suspension with a jack.
- Disconnect the ball joint from the steering knuckle.
- Remove the front and rear control arm bolts.
- Remove the control arm from the vehicle.
- Install new components, torquing the ball joint to the knuckle to 80 Nm
- Install the front control arm mounting bolt and tighten to 120 Nm + 90 degrees.
- Install the rear control arm mounting bolt and tighten to 120 Nm + 90 degrees.
- Torque the wheel lugs to 140Nm.
- Recheck torque settings after 50-100 miles
Technical Service Bulletins
Front Suspension Noise During Cold Weather
2020-11-15Some 2018-2020 BMW 840i models may experience front suspension creaking or knocking noise during cold temperatures. This is usually due to the sway bar links.
Resolution: Replace the front sway bar links with an updated part. Verify proper torque of all fasteners. Apply lubricant to polyurethane components of the suspension.
Rear Shock Absorber Leaking Issue
2021-05-20Certain 2019-2021 BMW 840i models have reported issues with rear shock absorber leakage. This issue requires replacement of the affected components.
Resolution: Replace both rear shock absorbers using the latest revision part. Verify correct torque specification during installation. Check for damaged hardware.
Front Control Arm Bushing Failure
2022-09-10Some 2020-2022 BMW 840i models are experiencing premature failure of the front control arm bushings. This will result in vibrations and clunking noises during driving.
Resolution: Replace the front control arms with updated bushings using the latest revision part. Verify proper torque specification during installation and ensure the correct alignment settings are set.
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Technical Information
- All specifications, including torque values, fluid capacities, and maintenance procedures, should be verified against your vehicle's factory service manual.
- Vehicle specifications and procedures may vary by model year, trim level, and region.
- Always follow the manufacturer's recommended procedures and safety precautions.
- Working on vehicles can be dangerous. Always take proper safety precautions and use appropriate safety equipment.
- If you're unsure about any procedure, consult a qualified professional mechanic.