Differential

Key takeaways

Key functions: A differential is installed on the axle shafts between wheels allowing the wheels to rate at different speeds. It also plays an important role in transferring the torque from the engine to the wheels.

Differential features: It is a complex assembly containing a big ring gear, a pinion gear, one or more spider gears, and two side gears. The pinion gear sends the torque from the engine to the ring gear. The spider gear rotates with the ring gear and passes the torque to the side gears, which connect to the wheels. The spider gear can also rotate on its own axis and so to allow the side gears to rotate at a different speed.

What is a differential?

The differential is an ingeniously designed mechanical part that you can find on every 4-wheel car. It can control and pass the torque from the engine to the driving wheels. A hypoid gear set (a ring gear and a pinion gear) is used to change the direction of the torque from the engine so that the power can make the drive wheels rotate. The inside of a differential is filled with fluid to keep every gear lubricated and minimize friction.

There are usually two or four spider gears in a differential nowadays to endure higher torque. The spider gears always move with the ring gear. They contact the side gears and make them rotate. If the car is going strictly straight, the spider gears will only rotate around the axis of the ring gear. If the car is turning left or right, two wheels will move at different speeds and so the side gears and the spider gears will rotate on their own axis to pass different torque to different wheels. This mechanism is important because if the wheels are rotating at different speeds and they are still getting the same amount of energy from the engine, one of them will have to skid to release the energy.

One circumstance that a traditional differential can’t deal with is when a drive wheel loses traction on a slippery road. The differential will pass more energy to the faster wheel, and this is great when the car is turning. But when a wheel loses traction, the wheel speed will be very fast. The differential will give a significant amount of power to the wheel that loses traction. Meanwhile, the wheel that remains gripped only gets little power. In this kind of situation, the car won’t be able to move. In order to deal with this problem, the limited-slip differential was introduced. In short, a limited slip differential can disengage the side gear of the low traction side so that the power can go to the high traction side. In this way, the limited-slip differential can act as a standard differential when the traction is normal, and prevent all the power from going to a slippery wheel when the traction situation is complex.

Normally, a differential does not break easily. But if it does encounter some problems, the longer these problems are left untreated, the higher it can cost when you finally manage to get it fixed. Here are some common symptoms that can indicate a differential problem.

Signs of a bad differential

• Abnormal tire wear: one of the differential’s jobs is to allow the drive wheels to rotate at different speeds. If the differential fails, the tires spin at the same rate during cornering, this can cause excessive wear to the tires.
• Abnormal noise: chattering noises, clunking sounds, and whining noises are often the symptoms that indicate your differential is failing. The whining noise could be caused by the ring gear and pinion gear. The chattering noise could be from the sticking clutch packs of a limited-slip differential. The clunking sound could be made for many reasons, but it is still a good sign telling you that it’s time to drain the fluid and check inside the differential.
• Leaking fluid: the differential is filled with fluid to reduce the friction between metal parts. If the seal is worn out, the fluid inside the differential can leak out. Without enough lubrication, the direct contact of the metal parts can dramatically reduce the lifetime of the differential.
• Metal shavings: when you drain the fluid, if you notice it is contaminated with metal shavings, you need to do more than just change the gear fluid. It is highly likely that the differential is failing internally.

Cost to fix a differential

Just like this article mentioned above, the differential is quite robust. But if it breaks, not only the part itself can cost you some money, but also the labor cost since it is a labor-intensive job to change or fix a differential. The good news is, here at A-Premium, we provide the highest quality differential with affordable prices and our famous A-Premium Service. If you need a new differential, your best choice is here.