Differential Parts

What is inside a differential

A differential lets the left and right wheels turn at different speeds in a corner while sending torque to both. The ring gear bolts to a carrier, the pinion gear drives the ring, and bearings support both. Seals keep gear oil in, and gaskets or covers close the housing. Because gears wear as a matched set, the ring and pinion are always replaced together.

Common replacement and upgrade parts

• Pinion seal and yoke: A leaking pinion seal is a frequent repair. A worn yoke surface can cause the new seal to leak again.
• Crush sleeve: A single-use spacer that sets pinion bearing preload on many axles. It must be replaced when the pinion is removed.
• Bearings and shims: Set gear position and backlash. Bearing wear shows up as whining or rumbling.
• Carriers and locker or open assemblies: Used when swapping to a different gear ratio, repairing damage or changing to a locking or open design.
• Gasket and cover parts: Reseal the housing after service.

Choosing the right part

Differential parts are specific to the axle model, not just the vehicle. Identify the axle first, such as a Dana 30, a GM 14 bolt or a Ford 10.25 inch, along with the spline count, ring gear diameter and ratio. Spline count and carrier bearing size must match your axle shafts. Always compare the part number against the manufacturer's specifications and confirm fitment for your exact year, make and model.

Installation notes

Setting up a ring and pinion requires correct pinion depth, bearing preload and backlash, usually checked with a dial indicator and marking compound. Mistakes cause noise and rapid wear, so many owners have this work done by a qualified shop. Use the gear oil grade and any friction modifier the manufacturer calls for, especially with limited-slip designs, and torque fasteners to specification. Break in new gears with gentle driving and change the oil after the first short interval.

Keep records as you work. Note the ring gear size, ratio, spline count and the lot or part numbers on each component, because future repairs are far easier when you know what is inside the housing. Inspect the gear oil for metal flakes, which can reveal bearing or gear wear before a failure.

How to confirm what you need before ordering

Start by pulling the axle cover or reading the tag, then write down the ring gear diameter, the ratio stamped on the ring gear or tag and the number of cover bolts. Next, decide whether you are repairing, regearing or adding a locker, because each job needs a different parts list.

• Repair: seals, bearings, crush sleeve, gasket or sealant and fresh gear oil.
• Regear: a matched ring and pinion, an installation kit and often a new carrier bearing set.
• Locker or carrier swap: a carrier matched to the ring gear bolt pattern and axle spline count.

Take careful notes on pinion yoke style and U-joint size too, since a worn yoke or a different driveshaft joint changes what you need. Avoid reusing old bearings with new gears, because their wear pattern will not match the new contact surface.