Step by step explanation on how an automotive differential works. This information pertains to all vehicles.

Step 1 - An automotive differential is used to evenly distribute engine power to the drive wheels. These differentials exist in every vehicle which drive either front or rear wheels. Some vehicles utilizes front and rear wheel drive commonly known as four wheel drive. This is achieved through the use of a transfer case, which separates engine power into two drive shafts.

Automotive Differential

Step 2 - Inside the differential is a ring gear which is driven by a pinion gear (not in view.) This particular differential is equipped with a locker, which can sense wheel slip to couple the spider gears forcing both drive wheels to work as one.

Ring Gear and Locker

Step 3 - A pinion shaft is used to hold the spider gears in place while positioning each axle as to hold a retainer clip in place.

Pinion Shaft

Step 4 - A differential is equipped with a set of spider gears (four) which are used to allow each wheel to turn independently of each other. This operation is necessary for the vehicle to turn smoothly as the inner wheel will travel less distance than the outer wheel.

Spider Gears

Step 5 - Some differentials are designed with an axle retainer clip which is used to hold the axle in place.

Axle Retainer Clip

Step 6 - This retainer clip is responsible for holding the axles in place. The pinion shaft holds these clips (2) onto the axles securely.

Removed Axle Retainer Clip

Step 7 - An axle shaft is fastened into the differential to supply power which the ring and pinion gears have transformed by transferring energy to the wheels.

Axle Shaft

Step 8 - An axle bearing supplies a roller surface for the axle to ride against. This bearing is capable of handling the operating weight of the vehicle and is lubricated by differential gear oil.

Axle Bearing

Step 9 - Both axles and the pinion gear utilize a seal which contains the differential gear oil for lubrication.

Axle Seal

Step 10 - A gasket is used to seal the rear cover to the differential housing.

Differential Cover Gasket

Step 11 - A magnet is used to gather stray metal particles which are the result of metal parts meshing together. This magnet should be cleaned when servicing the differential.

Particle Magnet

Step 12 - A metal cover is used to contain differential gear oil, which is held in place using multiple mounting bolts.

Differential Cover

Step 13 - A differential is designed to maintain a level of gear oil lubricant, this check is done by removing the fill plug.

Gear Oil Level and Pinion Yoke

Helpful Information

A differential is connected to the transmission, which is driven by the engine. A driveshaft connects the transmission to the differential which is responsible for determining the number of rotations the axles will turn in relation to the driveshaft. Gear ratio's are used to multiply engine torque delivered to the drive wheels. Ring and pinion gears are helical cut for smooth operation.

Differential gear oil level should be checked and serviced according the manufacturers recommendations. Inspect fluid consistency along with contaminants, which could be a sign of bearing or gear operation failure. Any abnormal noises should be addressed before permanent damage occurs.


Written by
Co-Founder and CEO of
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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