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
The differential relies on two sets of tapered roller bearings: pinion bearings that support the pinion gear, and carrier (side) bearings that support the differential case and ring gear. Worn bearings cause noise and, if ignored, can ruin the gearset.
Bearing replacement means setting bearing preload again, which also affects the gear mesh, so it is done with the same care as gear setup.
Common signs
- Rumble or growl that is present whether accelerating or coasting
- Noise that changes with speed rather than load
- Play in the pinion yoke or flange
What the work usually involves
- Confirm the noise source by road test and inspection, ruling out wheel bearings and tires
- Replace pinion and/or carrier bearings and races
- Set pinion preload and carrier bearing preload, recheck backlash and contact pattern
- Replace the pinion seal and refill with specified lubricant
Steps vary by vehicle and component design. Values and procedures come from the manufacturer's service information.
Vehicles this applies to
Light-duty cars and trucks through Class 8 trucks; heavy-duty carriers have their own procedures and specifications.
Key terms
Gear backlash
The small amount of free movement between the ring gear and pinion teeth. Some clearance is needed for lubrication and heat expansion; too little or too much causes noise and accelerated wear. It is measured with a dial indicator, and the allowable range comes from the axle manufacturer.
Bearing preload
A controlled load applied to tapered roller bearings during assembly so they run without free play. Depending on the design it is set with shims, a crush sleeve or threaded adjusters, and is commonly checked as rotating torque. Preload values are specific to each axle and must come from the manufacturer.
Tooth contact pattern
The marking left on the ring gear teeth after they are coated with gear-marking compound and rotated under resistance. Technicians read the pattern on both the drive and coast sides to confirm pinion depth and backlash before final assembly.
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.
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.