Manufacturer specifications apply. This page explains concepts only. Torque values, clearances, preload, backlash ranges and procedures vary by axle model and must come from the vehicle or component manufacturer's service information. This directory does not publish repair specifications.
What this service covers
Many truck axle complaints start in the suspension: worn spring bushings, torque rods, U-bolts, air springs or mounts let the axle move out of position, which upsets alignment, driveline angles and tire wear.
Diagnostics look at the axle, suspension and driveline together so the root cause is fixed, not just the symptom.
Common signs
- Driveline vibration that changes with load
- Axle walk or clunk on starts and stops
- Uneven drive or trailer tire wear
- Air suspension that doesn't hold ride height
What the work usually involves
- Inspect and measure suspension components, mounts and fasteners
- Check ride height on air suspensions against the manufacturer's setting
- Measure driveline operating angles and axle alignment
- Recommend and complete repairs, then verify by road test
Steps vary by vehicle and component design. Values and procedures come from the manufacturer's service information.
Vehicles this applies to
Class 3–8 commercial trucks, tractors and trailers.
Key terms
Tandem drive axle
Two driven rear axles on a heavy truck, the forward-rear and rear-rear axles, which share the load and the driving torque. Common on Class 8 tractors, dump trucks and vocational trucks.
Driveline operating angle
The angle at each U-joint between the two shafts it connects. A standard cross-type U-joint speeds up and slows down slightly within each turn when it operates at an angle; drivelines are designed so these fluctuations cancel out. Allowable angles come from the vehicle and driveline manufacturer.
Thrust angle
The direction the rear axle points compared to the vehicle's geometric centerline. A thrust angle that is out of specification can make the vehicle track sideways ('dog-track') and leave the steering wheel off-center.
Choosing a shop
- Confirm the shop works on your vehicle class and, for trucks, your axle make.
- Ask what parts they install (new, remanufactured or rebuilt) and what warranty applies.
- Check the listing's verification status and date in this directory.