REAR AXLE AND SUSPENSION Visual Inspection Visually check for loose or missing fasteners, cracks in hanger, or axle connection brackets. Rear Suspension Fasteners For all vehicles, mandatory maintenance procedures include retightening of U-bolts and complete inspection. However, even with proper maintenance, many factors affect the service life of springs and suspension components, such as: fatigue, vehicle gross weight, type of load, road conditions, and vehicle speed. To maintain the performance of the air suspension, check fastener torque values after the first 2,000 miles (3,218 km) of service and every 60,000 miles (96,000 km) thereafter.
Check that springs are centered in hangers and in good condition. Check for cracks, wear marks, splits, or other defects on the surface of the spring. Torque recommendations apply to fasteners supplied and installed by vehicle manufacture. The values listed in the tables below, are for cadmium plated or phosphate and oil fasteners only. Replace defective parts. Because repaired springs cannot be fully restored to their original service life, replace the complete assembly if cracks or other defects are detected. It is important that U-bolts remain tight. Severe use of your vehicle can cause them to loosen faster. But all vehicles need to have their U-bolts checked and tightened regularly.
Be sure someone with the proper training and the right tools checks and tightens the U-bolts on your vehicle. U-bolts are difficult to tighten unless you have the right equipment. If you cannot tighten them correctly yourself, be sure to have them checked and tightened regularly by an authorized mechanic. 5 After replacement of any part or discovery of loose components, check the torque of all fasteners. After the first 500 miles (800 km) of operation, inspect the suspension periodically, as noted below: New springs settle-in after the vehicle's initial service, causing the U-bolts to become loose. 5-132 Y53-6077-1B1 (03/17)