GMC Jimmy 1970-1991 Brake System Bolt Torque Specifications & Fastener Values
GMC Jimmy 1970-1991

GMC Jimmy 1970-1991 Brake System Bolt Torque Specifications

Detailed brake bolt torque specifications for the 1970-1991 GMC Jimmy, including caliper, rotor, and wheel hub 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

Brake Caliper

This subsystem includes components related to the brake caliper, which houses the brake pads and applies pressure to the rotor to slow or stop the vehicle.

1

Brake Caliper Bolts

M12 x 1.5
Torque Value
75 ft-lbs (102 N·m)
Important Notes
Ensure the caliper is properly aligned before torquing. Estimated value based on typical M12 bolt torque.
2

Brake Caliper Mounting Bracket Bolts

M14 x 1.5
Torque Value
90 ft-lbs (122 N·m)
Important Notes
Ensure the bracket is properly seated before torquing. Estimated value based on typical M14 bolt torque.

Brake Rotor Drum

This subsystem includes components related to the brake rotor or drum, which the brake pads or shoes press against to create friction and slow the vehicle.

1

Brake Disc/Drum Retaining Bolts

M10 x 1.25
Torque Value
55 ft-lbs (75 N·m)
Important Notes
Ensure the rotor or drum is properly seated before torquing. Estimated value based on typical M10 bolt torque.

Wheel Assembly

This subsystem includes components related to the wheel assembly, which directly affects the stability and alignment of the brake rotor.

1

Wheel Lug Nuts

M12 x 1.5
Torque Value
90 ft-lbs (122 N·m)
Important Notes
Ensure the wheel is properly seated before torquing. Estimated value based on typical M12 bolt torque.

Brake Hydraulics

This subsystem includes components related to the brake hydraulic system, which transmits the force from the brake pedal to the brake calipers or wheel cylinders.

1

Brake Hose Banjo Bolt

M10 x 1.0
Torque Value
22.5 ft-lbs (30.5 N·m)
Important Notes
Ensure the banjo bolt is properly aligned with the brake hose. Estimated value based on typical M10 bolt torque.
2

Brake Master Cylinder Mounting Bolts

M8 x 1.25
Torque Value
17.5 ft-lbs (23.7 N·m)
Important Notes
Ensure the master cylinder is properly seated before torquing. Estimated value based on typical M8 bolt torque.
3

Brake Booster Mounting Bolts

M8 x 1.25
Torque Value
17.5 ft-lbs (23.7 N·m)
Important Notes
Ensure the brake booster is properly seated before torquing. Estimated value based on typical M8 bolt torque.
4

Brake Line Fittings

M10 x 1.0
Torque Value
12.5 ft-lbs (16.9 N·m)
Important Notes
Ensure the fittings are properly aligned before torquing. Estimated value based on typical M10 bolt torque.

Parking Brake

This subsystem includes components related to the parking brake, which is used to keep the vehicle stationary when parked.

1

Parking Brake Cable Bracket Bolts

M8 x 1.25
Torque Value
17.5 ft-lbs (23.7 N·m)
Important Notes
Ensure the bracket is properly aligned before torquing. Estimated value based on typical M8 bolt 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

What is the recommended torque for brake caliper bolts on a 1970-1991 GMC Jimmy?

The recommended torque for brake caliper bolts on a 1970-1991 GMC Jimmy is typically between 25-35 ft-lbs (34-47 Nm). Always refer to the vehicle's service manual for exact specifications, as variations may exist depending on the model year and brake system configuration.

Q2

How often should brake components be inspected for proper torque?

Brake components, including bolts, should be inspected for proper torque during every brake service or at least once a year. Loose bolts can lead to brake failure, so it's crucial to ensure they are tightened to the manufacturer's specifications.

Q3

Can over-tightening brake bolts cause damage?

Yes, over-tightening brake bolts can strip threads, damage components, or cause warping of brake parts. Always use a calibrated torque wrench and follow the manufacturer's specifications to avoid over-tightening.

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

A precision tool used to apply a specific torque to a fastener such as a bolt or nut.

  • Adjustable torque settings
  • Calibrated for accuracy
Learn more

Breaker Bar

A long-handled tool used to loosen tight bolts before applying torque.

  • Durable construction
  • Extended leverage
Learn more

Socket Set

A set of sockets in various sizes to fit brake system bolts.

  • Metric and standard sizes
  • Deep and shallow sockets
Learn more
Service Procedures

Brake Caliper Bolt Torque Specification

Procedure to properly torque the brake caliper bolts on a 1970-1991 GMC Jimmy.

  • Lift the vehicle and secure it on jack stands.
  • Remove the wheel to access the brake caliper.
  • Use a breaker bar to loosen the caliper bolts.
  • Clean the bolt threads and apply a small amount of thread locker if recommended.
  • Tighten the caliper bolts to the specified torque using a torque wrench. For 1970-1991 GMC Jimmy, the torque specification is typically 35-40 ft-lbs.
  • Reinstall the wheel and lower the vehicle.
View full procedure

Brake Rotor Bolt Torque Specification

Procedure to properly torque the brake rotor bolts on a 1970-1991 GMC Jimmy.

  • Lift the vehicle and secure it on jack stands.
  • Remove the wheel and brake caliper to access the rotor.
  • Use a breaker bar to loosen the rotor bolts.
  • Clean the bolt threads and apply a small amount of thread locker if recommended.
  • Tighten the rotor bolts to the specified torque using a torque wrench. For 1970-1991 GMC Jimmy, the torque specification is typically 15-20 ft-lbs.
  • Reinstall the brake caliper and wheel, then lower the vehicle.
View full procedure
Technical Service Bulletins

Brake System Bolt Torque Recall

1985-03-15

A recall was issued for certain 1970-1991 GMC Jimmy models due to improper torque application on brake system bolts, leading to potential brake failure.

1970-1991 GMC Jimmy

Resolution: Inspect and retorque all brake system bolts to the manufacturer's specifications. Replace any damaged or worn bolts.

Brake Caliper Bolt Loosening Issue

1988-07-22

A technical bulletin was issued regarding brake caliper bolts loosening over time on 1970-1991 GMC Jimmy models.

1970-1991 GMC Jimmy

Resolution: Apply thread locker to the caliper bolts and ensure they are torqued to the specified 35-40 ft-lbs during service.

About the Author

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Alan Montanye - Automotive Technical Specialist
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Alan Montanye

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