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
Class 7 and 8 trucks use heavy-duty drive axles with large carriers, often in tandem pairs, built by axle manufacturers with their own service procedures. Single-reduction and two-speed designs are both common.
Drive axle service includes carrier inspection and rebuild, axle shaft and wheel-end work, lubrication, and diagnosing noise or leaks under load.
Common signs
- Gear or bearing noise under load
- Lube leaks at the carrier, axle flange or hub
- Metal in the lube at a service interval
- Overheating axle or burnt lube smell
What the work usually involves
- Inspection and lube service with the lubricant and fill method the axle manufacturer specifies
- Carrier removal and rebuild, or exchange with a remanufactured carrier
- Gear setup and bearing adjustment to the axle manufacturer's specifications
- Inspection of shafts, studs, wheel ends and seals
Steps vary by vehicle and component design. Values and procedures come from the manufacturer's service information.
Vehicles this applies to
Class 7–8 tractors, dump trucks, vocational trucks and fleet vehicles; similar work applies to many Class 6 trucks.
Key terms
Ring and pinion gearset
The final-drive gear pair inside the differential. The smaller pinion gear, turned by the driveshaft, drives the larger ring gear. The tooth-count ratio between them is the axle ratio (for example, 3.73:1). Ring and pinion gears are matched sets and are set up together.
Differential carrier
Depending on axle design, 'carrier' means either the case that holds the side and spider gears (with the ring gear bolted to it) or the complete removable center section of the axle, sometimes called a third member.
Full-floating axle
The wheel hub rides on its own bearings on a spindle that is part of the axle housing, so the housing carries the vehicle's weight and the axle shaft only transmits torque. Common on many 3/4-ton and 1-ton pickups and on commercial trucks.
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.
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.