On rear-wheel-drive and all-wheel-drive vehicles, the rear differential plays an essential role. Not only does the rear differential help deliver engine horsepower and torque to the rear wheels, but it also allows the wheels to rotate at different speeds while cornering.

As long as it's serviced properly, a rear differential can last for the life of your vehicle. However, the following issues can make short work of your differential if it's not serviced in time.

1. Fluid Leaks

Like any other component that relies on moving parts, your rear differential needs constant lubrication for smooth and consistent operation. Nearly every moving part inside of the differential is kept in a constant bath of gear oil to reduce friction from metal-on-metal contact. A gasket made from rubber, cork, or silicone helps maintain a seal between the rear differential housing and its cover.

Leaks aren't uncommon for rear differentials. Gaskets can fail with time, age, and external damage, making them prone to leakage. A loose or damaged differential cover can also leak gear oil. Leaks can also happen if the differential housing itself suffers any severe damage.

A rear differential leak can eventually result in low fluid levels. The resulting lack of lubrication can damage internal components, leading to gear whine upon acceleration or at certain speeds. If you spot traces of gear oil on the underside of the differential or on the ground underneath the vehicle, you should have it checked out by your mechanic.

2. Fluid Failure

Differential lubricants can also wear out and lose their effectiveness as time goes on. How often you'll need to change your gear oil depends on your manufacturer's recommendations. Some recommend differential fluid changes every 30,000 miles, while others go as far as 150,000 miles before recommending a change. Other factors, such as towing and aggressive driving, can cause fluid changes to come sooner rather than later.

Waiting too long for a differential fluid change can have disastrous consequences. Differential lubricants can lose their viscosity as they wear out, allowing friction and heat within the differential to reach dangerous levels. Eventually, the fluid becomes too worn out to protect against damage caused by metal-on-metal contact.

Differential fluid failure can cause serious damage to your rear differential's internals. If you haven't checked or changed your fluid within the last 30,000 miles, you should have it looked at by a professional.

3. Worn Bearings

Your rear differential also contains several bearings that not only facilitate smooth movement, but also help support the axles. These bearings can wear out over time, resulting in loud rumbling or whirling noises that can be heard at high speeds. Shavings and other debris from bad bearings can also contaminate the differential fluid, and the excess friction caused by failed bearings can also cause the fluid to break down sooner.

Worn bearings should be inspected as soon as possible to minimize the potential damage they can cause to your rear differential.

4. Universal Joint Failure

The rear differential and driveshaft are connected by a series of universal joints, also known as "U-joints." These joints allow for a more flexible connection between the transmission, driveshaft, and differential, thereby overcoming height differences between all three components. Many rear-wheel-drive and all-wheel-drive vehicles also use constant velocity or CV joints for the same reason.

A failing U-joint can knock the driveshaft out of balance, resulting in vibrations that increase in intensity as your vehicle's speed increase. Problematic U-joints can also cause clunking noises upon acceleration. U-joint problems can also lead to ring or pinion gear failure due to the stresses placed on the differential.

To learn more, contact a company like Huntington Beach Transmissions.