Air Suspension Maintenance
Detecting Leaks & Restricted Airflow
- If both sides of the suspension are flat, there may be a leak between the air brake system and the suspension air system.
- If one side is flat, check for a leak between the height control valve and the air spring.
Automatic Height Control Valve Testing
- Disconnect the linkage and move the actuating arm up and down.
- If working correctly, the airbag should inflate and deflate accordingly.
Bushing Inspection
- Use a pry bar between the trailing arm and the hanger to check for movement.
- Abnormal tire wear is a strong indicator of worn bushings.
Shock Absorber Performance Check
- After operation, shocks should be warm to the touch. Cold shocks indicate a malfunction and require replacement.
- If the shock compresses too easily after removal, it should be replaced.
- Inspect shock bushings for wear.
Airbag Inflation & Failure Prevention
- A slight positive pressure maintains the airbag shape and prevents folding or pinching.
- Common causes of air spring failure:
- Overextension
- Abrasion
- Contamination
- Suspension misalignment
- Road hazards
- Fatigue and aging
Leaf Spring Suspension Maintenance
Key Inspection Points
- Spring leaves for cracks or damage.
- Center bolt condition.
- U-bolt nuts – ensure tightness and correct torque.
- Spring clips and spring eyes – check for cracks, motion, and proper lubrication.
- Front suspension spring shackle bolts – inspect for wear.
- Torque rods and other related suspension parts – including hangers, equalizers, and beam bushings.
- Shock absorbers – check for leaks and proper function.
Preventable Suspension Failures
U-Bolts
- Never reuse U-bolts!
- Ensure they are the correct grade.
- Proper alignment is crucial – check the top plate and saddle alignment holes.
- Allow the suspension to settle before re-torquing under load.
- Torque U-bolts per specifications and re-torque at 500 miles; continue periodic checks.
Spring Fatigue & Cracking
- Proper U-bolt maintenance extends spring life.
- Cracks are the primary sign of fatigue.
- Brake balance is crucial – poorly adjusted brakes overwork certain springs, leading to premature wear.
Torque Rod Neglect
- Affects spring life, bushings, brackets, bolsters, shocks, airbags, and other suspension components.
- Inspect regularly, especially transverse rods.
Lubrication Failures
- Lack of lubrication restricts movement and causes premature breakage.
- Excessive wear and exaggerated wear patterns result from poor lubrication.
Bushing Wear & Replacement Timing
- Delaying bushing replacement can lead to costly secondary repairs.
Shock Absorber Neglect
- Impacts spring life, bushings, and other suspension parts.
- Increases strain and vibration on radiators, electrical systems, cabs, and tires.
- Defective shocks contribute to airbag failure.
Final Thoughts
Regular suspension maintenance is a critical component of vehicle safety and efficiency. By inspecting for leaks, testing components, and staying proactive with part replacements, you can extend the life of your suspension system and avoid costly repairs. Don’t wait for a failure—schedule routine checks and keep your truck running smoothly!
