Everything You Need to Know About Wheel Bearings and the Noises They Make
One of the most frequent concerns raised by vehicle owners is the suspicion that “my car is making an unusual noise”. While cars are intricate machines capable of producing a variety of sounds from multiple sources, wheel bearings are among the key components that often cause noise when they begin to fail. This detailed guide will help you understand what a bad wheel bearing sounds like, and what steps are necessary to address the issue effectively.
What Is a Wheel Bearing?
Your vehicle’s wheels rotate around a stationary axle, and to facilitate this motion, a wheel bearing is essential. The wheel hub, which attaches the wheel to the vehicle, incorporates the bearing assembly—sometimes comprising both inner and outer bearings. In essence, a wheel bearing allows the wheel to spin smoothly while supporting the vehicle’s weight.
Most wheel bearings consist of small balls or cylindrical rollers positioned between two smooth metal rings—one fixed to the hub and the other around the axle. These components are designed to reduce friction and support rotational movement. The assembly often includes side plates that seal in lubricating grease, protecting the internal parts from dirt and moisture.
Given their constant exposure to road conditions, wheel bearings endure a tough life. The balls or rollers, roughly the size of a pencil or AA battery, are subjected to immense forces as they support the weight of the vehicle and facilitate high-speed rotation. While many bearings last up to 100,000 miles, wear and tear are inevitable due to various factors such as normal aging, impact damage, and environmental exposure.
What Is the Typical Lifespan of a Wheel Bearing?
On average, wheel bearings tend to last between approximately 85,000 and 100,000 miles (136,000 to 160,000 km). However, this lifespan can vary significantly depending on the quality of the bearing itself and the operating conditions it encounters. Proper maintenance and cautious driving can prolong their service life, while harsh conditions and rough roads tend to accelerate wear.
Key Indicators of a Failing Wheel Bearing
Recognizing early signs of wheel bearing failure is crucial for safety and cost management. Here are six essential symptoms to watch out for:
- Steering Wheel Vibrations: Unusual steering wheel vibrations, apart from a loose steering wheel, can be a sign of a compromised wheel bearing. The vibration often increases at higher speeds or during turns.
- Unusual Noises: A distinctive grinding, grating, or humming noise emanating from the wheel area, especially as speed increases, suggests a worn or damaged bearing.
- Loose Steering Response: A decrease in steering responsiveness or a feeling of looseness when maneuvering can indicate bearing issues.
- Uneven Tire Wear: Excessive or uneven tire wear patterns might be linked to bearing problems, as misaligned or loose bearings affect tire contact with the road.
- Brake System Anomalies: If braking feels less effective or there are unusual brake slips, suspect that a faulty bearing might be interfering with brake operation.
- ABS Warning Light: An illuminated Anti-lock Braking System (ABS) warning light can be related to abnormal pressure or sensor issues caused by bearing wear or damage.
Detecting the Sound of a Bad Wheel Bearing
Common auditory signs include:
- Humming: A persistent humming noise while driving can stem from wheel bearing issues or CV joints, among other causes.
- Squealing or Growling: Cyclical squealing, squeaking, or growling sounds, which typically change with vehicle speed, are classic indicators of bearing deterioration.
- Howling: Howling noises may occur during deceleration, indicating loose pinion-bearing preload, whereas continuous howling under acceleration suggests worn gears or bearings that aren’t supporting the load properly.
Causes of Noise and Damage in Wheel Bearings
Since wheel bearings are in constant motion, various factors can lead to noise generation or damage, including:
#1. Normal Wear and Tear
Over time, continuous use causes the internal components of wheel bearings to degrade naturally. The constant rotation, stress, and environmental exposure gradually wear down the balls or rollers, leading to increased friction and noise. Addressing worn bearings promptly is essential to prevent further damage.
#2. Rough Road Conditions
Driving over potholes, curbs, and uneven surfaces exerts additional stress on wheel bearings. Impact damages can create microscopic flaws that generate heat and friction, ultimately hastening bearing failure and noise production.
#3. Incorrect Installation
Improper mounting or assembly of wheel bearings can cause premature wear or damage. Ensuring professional installation with proper tools and adherence to manufacturer guidelines is critical for longevity and safety.
#4. Driving Through Water
Seals protect wheel bearings from contaminants, but repeated exposure to deep water can compromise these seals. Water ingress dilutes the lubricant, increasing friction and wear. Modern sealed bearings resist water better, but damage often necessitates replacement rather than repair.
#5. Unbalanced Tires and Worn Suspension Components
Tire imbalance or worn shocks and suspension parts place extra stress on wheel bearings, accelerating their deterioration and leading to noise and handling issues.
#6. Impact or Accident Damage
Collisions or impacts near the wheel area can damage the internal structure of bearings even if damage isn’t immediately apparent, resulting in noise and eventual failure.
#7. Manufacturing Defects
Though rare, some bearings may have factory defects that cause early wear or noise. In new vehicles, persistent bearing issues might point to such manufacturing flaws.
How to Diagnose a Failing Wheel Bearing
To evaluate your wheel bearing’s condition:
- Lift the vehicle using a floor jack until the tire is off the ground.
- Manually attempt to move the tire up and down, then side to side.
- If you notice wobbling or excessive free play, the bearing might be compromised.
For demonstration, refer to instructional videos illustrating how to perform this inspection effectively. Keep in mind that the severity of noise varies with the extent of damage.
Cost of Replacing a Wheel Bearing
Replacing a wheel bearing typically ranges from $250 to $600 per wheel, which includes parts and labor. The final cost depends on vehicle make, model, the shop’s hourly rate (usually between $47 and $215), and any additional damages encountered during replacement. For some vehicles, the expense can be less than $100 per wheel, especially if you opt for a DIY approach using tools borrowed from parts stores.
Important: Always replace the axle hub nut during bearing replacement. These nuts are often thread-sealed (prevailing torque fasteners) and are critical for secure and safe operation.
Is It Safe to Drive with a Suspected Bad Wheel Bearing?
If you suspect your wheel bearing is failing, it’s advisable to address the issue promptly. If driving is unavoidable, keep your speed low, avoid highway and long-distance driving, and monitor for worsening symptoms. Any increase in noise, vibration, or handling problems warrants stopping and inspecting the vehicle immediately.
Driving with a severely damaged bearing can lead to wheel seizing or detachment, risking driver safety. Additionally, prolonged operation can cause damage to other components like the hub, CV joint, or axle, resulting in more costly repairs and potential safety hazards.