Wheel bearings are a critical component in a vehicle’s suspension system. They allow the wheels to spin freely while supporting the weight of the vehicle.
Without properly functioning wheel bearings, the wheels would not be able to rotate smoothly or safely.
Wheel bearings consist of steel balls or rollers contained in a metal ring called a race. They are designed to handle both radial and thrust loads.
Radial loads push perpendicular to the axis of rotation, while thrust loads push parallel to the axis.
Modern wheel bearings are sealed units that are pre-packed with grease during manufacturing. This keeps contaminants out and lubrication in.
Proper functioning of wheel bearings is essential for safe handling and control of a vehicle. If the wheel bearings fail, it can lead to excessive wheel wobbling, noise, uneven tire wear, and steering wander.
In extreme cases, it may even lead to catastrophic separation of the wheel from the vehicle.
That’s why routine inspection and maintenance of wheel bearings is critical. Understanding why wheel bearings fail can help drivers and mechanics prevent problems before they occur.
What is a Wheel Bearing?
A wheel bearing is a set of steel balls or rollers contained in a metal ring called a race that sits between the wheel hub and spindle. The bearing allows the wheel to spin freely with minimal friction.
The main components of a wheel bearing are:
- Outer race – The stationary outer ring that sits in the wheel hub.
- Inner race – The inner ring that attaches to the spindle and rotates with the wheel.
- Ball bearings or tapered rollers – Steel balls or tapered rollers that roll between the races to allow smooth rotation.
- Cage – Holds the bearings or rollers in place as they roll.
- Seals – Rubber seals that keep lubricant in and contaminants out.
Wheel bearings must be properly lubricated to function. The ball bearings or tapered rollers roll freely between the greased inner and outer races, allowing the wheel hub and spindle to rotate independently.
This reduces friction when the wheel spins. Quality bearings that are properly lubricated can provide thousands of miles of smooth, quiet operation.
How Do Wheel Bearings Work?
Wheel bearings are a crucial component that allows the wheels on your vehicle to spin smoothly.
They are made up of steel balls or tapered rollers that are held together by a metal ring called a race.
The bearings are contained inside a metal housing that is sealed with rubber seals to keep out contaminants.
Inside the wheel hub is an inner and outer bearing. The inner bearing fits tightly over the spindle, while the outer bearing fits into the wheel hub.
A separate part called the hub sits between the inner and outer bearings.
When the wheel rotates, the hub spins around the axle spindle. The inner and outer bearings allow this motion by reducing friction between the spinning hub and the non-moving spindle.
The steel balls inside the bearings roll between the hub and the race, keeping the two surfaces separated. This allows the hub to spin with minimal friction.
Grease is packed into the bearings to lubricate them and reduce friction even further. Seals keep the grease in place and prevent dirt and moisture from contaminating the bearings. This helps prolong the life of the bearings and keeps them spinning smoothly.
Proper wheel bearing operation is critical for safe and comfortable driving. When bearings fail, it causes increased resistance while driving, noise, and can eventually lead to catastrophic failure.
That’s why routine inspection and maintenance is important for identifying potential problems early.
Common Causes of Wheel Bearing Failure
Wheel bearings can fail for a variety of reasons. Some of the most common causes include:
- Age and Mileage: Wheel bearings are wear items that gradually deteriorate over time and mileage. The grease inside the bearings breaks down and loses its lubricating properties. Seals wear out, allowing contaminants inside. Old and high-mileage bearings are more prone to failure.
- Damage: Impact damage from hitting curbs or potholes can damage the bearing components. Denting or deforming any part of the bearing assembly will lead to premature failure.
- Improper Installation: If a technician does not properly install new bearings using the correct tools and procedures, it may result in binding, uneven loading, or inadequate preload. This leads to early failure.
- Lack of Lubrication: Wheel bearings require frequent lubrication to remain healthy. If the grease dries up due to a torn seal or cap, or if it is not repacked often enough, the bearings will wear out faster.
Proper installation, routine maintenance, and avoiding damage are key to maximizing wheel bearing life.
But no bearing lasts forever – age and mileage will inevitably take a toll. Being aware of the common failure causes can help drivers prevent problems and recognize when a bearing needs attention.
Symptoms of a Failing Wheel Bearing
A failing wheel bearing will usually exhibit certain symptoms that can alert the driver of an issue.
Being aware of these signs can help prevent more serious problems from developing. Some of the most common symptoms of a worn wheel bearing include:
- Strange noises coming from the wheel area – This is often described as a humming, growling or roaring sound that changes pitch as wheel speed increases. The noise usually gets louder the faster you drive.
- Wheel wobbling – Bad bearings will allow more play in the wheel, which can cause wobbling or shaking. This may be noticeable when braking or making turns.
- Vibration felt in the steering wheel or seats – The extra movement in the wheel can translate into vibrations felt in the car. Many drivers first notice a vibration in the steering wheel or driver’s seat.
- Uneven tire wear – Excessive wheel play will cause abnormal tire wear. This may show up as bald spots or a choppy wear pattern on the tire tread.
- Pulling in one direction – If a bearing is failing on just one wheel, it may create a pulling sensation making the car drift to that side.
Paying attention to these signs of a failing bearing can prevent extensive damage from occurring. Any unusual noises, wobbling or vibrations from a wheel area should be inspected immediately.
Consequences of Wheel Bearing Failure
Wheel bearing failure can lead to some serious consequences if not addressed promptly. Here are some of the main risks and effects of driving with a failed bearing:
Safety Hazards
A collapsed or disintegrating bearing can cause the wheel to wobble or even detach from the vehicle entirely.
This poses a major safety hazard, as it can lead to loss of control and potential rollovers. A loose wheel can easily cause accidents or make the vehicle uncontrollable.
Impaired Handling
As the wheel bearing deteriorates, it will allow more play and wobble in the wheel. This can make the steering erratic and reduce stability.
Your ability to steer and handle the vehicle will be hindered, making it difficult to control.
Further Damage to Components
The excessive play and friction resulting from a failed bearing can also grind down brake rotors, destroy wheel hubs and put strain on axles.
If left unattended, a collapsed bearing can cause extensive damage to these other components that are much more costly to repair or replace.
In summary, it’s critical to address any potential wheel bearing issues immediately. Driving with a compromised bearing risks safety, reduces vehicle control and handling, and often leads to cascading damage of associated parts.
Don’t ignore the symptoms of a failing wheel bearing, as the consequences can be severe.
How to Diagnose a Bad Wheel Bearing
Diagnosing a failing wheel bearing early is crucial to avoid more extensive repairs. Here are the main ways to check for a bad wheel bearing:
Visual Inspection
Look for signs of leaking grease around the wheel and visible damage to the bearing seal. Any grease around the wheel likely indicates a damaged seal that has allowed lubricant to escape.
Inspect the tire tread wear. If the tread is significantly more worn on one side of the tire, it could point to a wheel bearing issue on that wheel.
Uneven or rapid tire wear can signify a misaligned wheel from a bad bearing.
Check for Play and Noise
Jack up the vehicle and support it securely on jack stands. Grab the wheel at the top and bottom and push and pull to feel for any looseness or play. There should be no discernible movement.
Rotate the wheel and listen closely for any growling, grinding or rumbling noises coming from the wheel area. Any unusual sounds likely indicate worn-out or damaged wheel bearings.
Use Diagnostic Tools
Mechanics often use a dial indicator gauge to check for play when diagnosing bad wheel bearings. The tool measures any wheel wobble or movement.
Infrared temperature sensors can identify overheating wheel bearings before complete failure. Higher than normal temperatures suggest bearing wear.
Vibration detectors and acoustic tests help identify noise patterns indicative of failing bearings. These advanced diagnostic tools can pinpoint the problem wheel(s).
Carefully checking for signs of wear and using diagnostic tools allows early detection of bad wheel bearings before they lead to dangerous failures.
Promptly replacing worn bearings reduces the risk of extensive damage to the wheels and other components.
Repairing or Replacing a Wheel Bearing
Replacing a bad wheel bearing is usually necessary once it has become damaged or worn out.
While it is possible to just replace the bearing inside the hub assembly, most mechanics recommend replacing the entire hub assembly for best results.
Here is an overview of the wheel bearing replacement process:
- The wheel will need to be removed from the vehicle to access the wheel hub assembly. This requires jacking up the vehicle and removing the tire and brake components.
- The hub assembly is held on by bolts that must be removed. A breaker bar is usually needed to loosen them due to how tight they get over time. Caution must be used to avoid damaging any ABS sensor wires.
- Once the hub assembly is off, the inner and outer bearing seals must be carefully removed. The old bearings can then be pressed out and new bearings pressed into place after thoroughly cleaning the hub bore.
- The hub assembly is then reinstalled in reverse order. Proper torque specifications must be followed when tightening the bolts back down.
- Finally, the brake components and wheel are reinstalled to complete the job.
For a typical passenger vehicle, the average cost for a professional mechanic to replace a wheel bearing is $150-$300 per wheel.
This cost can be higher for larger trucks. The parts themselves usually cost between $50-$150.
With some DIY mechanical skills, wheel bearing replacement can be done at home for much cheaper. However, having a shop do it ensures proper installation and adjustments.
So in summary, wheel bearing replacement requires disassembling the brakes and wheel components to access the hub assembly.
After removal, the old bearing is pressed out and a new one pressed in. Reassembly is done in reverse order of disassembly.
Overall it’s a straightforward job for mechanics and costs $150-$300 per wheel when done professionally. Proper replacement ensures the wheel spins freely and safely.
Preventing Wheel Bearing Failure
Routine inspection and maintenance are key to preventing premature wheel bearing failure.
Wheel bearings are sealed and lubricated, so they don’t require frequent servicing. However, there are some steps you can take to maximize their lifespan:
- Inspect tires and wheels regularly – Look for any signs of abnormal or uneven tire wear, which can indicate a bad wheel bearing. Also check wheels for any wobbling or vibration.
- Listen for sounds – If you hear growling, grinding or humming sounds from a wheel area as you drive, especially at higher speeds, it likely means a wheel bearing is wearing out. Address any unusual noises right away.
- Change oil regularly – The wheel bearings are lubricated by the engine oil. Keeping clean oil and regularly scheduled oil changes will help extend the life of the bearings.
- Align wheels properly – Improper wheel alignment puts more stress on wheel bearings and can lead to premature failure. Have the alignment checked whenever new tires are installed.
- Replace bearings in pairs – If one bearing is worn out, chances are the one on the opposite wheel is also near the end of its lifespan. Replacing in pairs helps prevent repeat breakdowns.
- Follow manufacturer service schedule – The owner’s manual will specify recommended intervals for inspecting, lubricating, and replacing wheel bearings based on driving conditions and mileage.
With vigilant monitoring and routine maintenance, wheel bearings can last for many tens of thousands of miles.
Catching problems early and replacing bearings before they fail completely will help prevent safety hazards and costly repairs down the road.
Conclusion
Wheel bearings are a crucial component of your vehicle’s suspension system. Their main function is to allow the wheels to spin freely while supporting the weight of the vehicle.
When wheel bearings start to fail, it can lead to a variety of problems including abnormal tire wear, wheel wobbling, grinding noises, and excessive vibration.
In severe cases, a collapsed bearing can cause the wheel to lock up while driving, leading to a loss of control.
It’s important to have any suspected wheel bearing issues inspected and repaired promptly. Driving on a bad bearing will only cause further damage over time.
Routine maintenance and inspections can help prevent premature bearing failure. Listen for noises and feel for vibrations when driving, as these are telltale signs of wear.
Replacing worn bearings early on is much less expensive than waiting for complete failure down the road.
Properly functioning wheel bearings are essential to your safety and the performance of your vehicle.
Paying attention to these components and having repairs done by a qualified mechanic will help avoid breakdowns and keep your wheels spinning smoothly for the long haul.
The conclusion summarizes the importance of functional wheel bearings for safe driving and preventing costly repairs. Maintaining and replacing bearings when needed is key.
