Wheel bearings are a critical component of your vehicle’s suspension system. They allow the wheels to spin freely while supporting the weight of the vehicle. However, like any mechanical part, wheel bearings can eventually wear out and fail. Understanding the common causes of wheel bearing damage can help you identify problems early and avoid more extensive repairs down the road.
What are wheel bearings?
Wheel bearings are sets of steel balls or tapered rollers contained in a metal ring called a race. They are located inside the wheel hubs, which are mounted to the vehicle’s suspension system. The bearings are fixed in place but spin freely, allowing the wheels to rotate with minimal friction.
Most modern vehicles use tapered roller bearings, which are comprised of two inner and outer bearings fitted together in sets of two in the hub assembly. The inner bearings sit closer to the spindle while the outer bearings are positioned near the outside of the hub. A solid metal spindle passes through the inner races and is fixed to the steering knuckle. The outer races are pressed into the wheel hub.
How do wheel bearings work?
As the wheel spins, the inner and outer bearings allow the hub and wheel to rotate freely around the spindle. At the same time, the bearings support side loads and absorb impacts from the road. A circular bearing retainer clip holds the bearings in place once they are packed with grease during assembly.
The grease lubricates the bearings as they spin. Seals on either side of the bearings keep the grease in and contaminants like dirt and water out. This allows the bearings to spin almost indefinitely without wear and maintenance.
What causes wheel bearings to fail?
While wheel bearings are designed to last tens of thousands of miles under normal conditions, several factors can contribute to premature bearing failure:
1. Age and mileage
Like any mechanical component, wheel bearings deteriorate with age and use. The steel balls/rollers and races experience wear every time the vehicle is driven. After enough accumulated miles, this can result in uneven surfaces, decreased clearance between parts and eventual bearing damage. For most modern vehicles, wheel bearings typically last between 80,000-100,000 miles.
2. Improper bearing installation
If a wheel bearing is not installed properly, it can lead to binding, uneven wear, loss of lubrication and eventual failure. Common mistakes include:
- Forgetting to pack the bearing with grease before installation
- Not fully seating the bearing during installation
- Not using the proper tools to press the bearing into the hub
- Installing the wrong bearing due to an application mismatch
- Applying too much or uneven pressure during press fit installation
3. Lack of maintenance
Routine maintenance helps preserve wheel bearings. But when maintenance is skipped or overlooked, wear accelerates. Neglected aspects include:
- Not regularly checking/changing axle fluid
- Failing to periodically repack bearings with fresh grease
- Not replacing seals that have cracked or failed
- Not addressing minor vibrations or noises that indicate bearing wear
4. Insufficient or incorrect lubrication
Wheel bearings require regular lubrication from axle fluid and bearing grease to prevent metal-on-metal contact. Without enough lubrication, the steel components grind against each other leading to overheating and eventual failure. Causes include:
- Low axle fluid level
- Old, diluted or incorrect grease
- Clogged grease fitting passages
- Failed seals allowing lubricant to leak
5. Excessive wheel loads
The heavier the load placed on the wheel bearings, the faster wear occurs. Heavier than designed wheel loads can be caused by:
- Carrying heavier payloads in trunk/bed
- Towing beyond vehicle rating
- Oversized wheels and tires
- Repeated hard cornering/impacts
6. Wheel imbalance
Out-of-balance wheels place uneven loads on bearings and races. The extra vibration wears bearings faster. Wheel imbalance can be the result of:
- Uneven tire wear
- Damage from hitting curbs
- Missing wheel weights
- Bent wheels
7. Misaligned wheels
Like imbalance, wheels that are misaligned place more stress on bearings compared to properly aligned wheels. Misalignment causes extra vibration and load on one side. This can be caused by:
- Colliding with road hazards like curbs
- Bent suspension components
- Worn steering/suspension parts
- Improper installation after suspension work
8. Excessive heat
Heat is the enemy of wheel bearings. Excessive heat causes the grease to soften and lose its lubricating properties. Overheated bearings are more prone to friction, wear and failure. Heat build up can result from:
- Insufficient grease
- Dragging brakes
- Wheel bearing defects
- Debris buildup inside the hub
9. Seals failure
The seals on either side of the wheel bearings keep contaminants out and lubricant in. When these seals are damaged or fail, dirt/debris can infiltrate the bearings. This leads to wear and corrosion. Causes of seal failure include:
- Normal wear and aging
- Incorrect seal installation
- Ripped or damaged seals
- Corrosion
10. Environmental contaminants
Exposure to contaminants like water, dirt/debris and road salt accelerate wear of wheel bearings. Contaminants lead to corrosion and abrasion inside the bearings. Inadequate seals, damaged boots and negligent maintenance allows entry of contaminants.
Signs of failing wheel bearings
Many drivers don’t notice their wheel bearings are failing until it’s too late. But there are early warning signs to look out for:
- Noise – Grinding, rumbling or growling noises coming from the wheel can indicate bearing damage
- Vibration – Excess vibration through the steering wheel can signal an inner bearing starting to fail
- Wobbling – If an outer bearing is failing, the wheel may wobble noticeably while driving
- Looseness – Too much play in the wheel when rocked indicates bearing wear
- ABS light – The ABS system often detects inconsistent rotational speeds when a bearing is failing
- Smoke/smell – Overheating bearings may produce burning smells or even smoke
- Fluid leakage – Grease leaking out around the seal is a sign the seal has failed
Addressing these warning signs quickly can allow for minor repairs versus complete hub replacement if the bearings are allowed to fail completely.
How to make wheel bearings last
While wheel bearings are wear parts designed to operate for thousands of miles, you can maximize their lifespan by:
- Driving smoothly – Minimize hard braking and cornering which place added stress on bearings
- Maintaining proper wheel alignment
- Balancing tires regularly
- Not overloading vehicle or trailer
- Checking/changing differential fluid regularly
- Addressing any bearing noises/vibration immediately
- Keeping seals protected from damage
- Avoiding potholes/road hazards
- Washing mud/debris off regularly to prevent contaminant buildup
Catching problems early is key to minimizing repair costs. Listen for changes in sounds from the wheels and pay attention to vibrations. Address these warning signs right away by having your shop inspect the bearings.
When to replace wheel bearings
Most mechanics recommend replacing wheel bearings once they have reached about 100,000 miles. Even if the bearings don’t yet show obvious signs of wear, the seals have likely aged to the point of increased failure risk. Replacing the bearings provides an opportunity to install new seals and grease for maximum life.
However, earlier bearing replacement may be advisable if you notice any unusual noise, wobble or vibration from a wheel. This indicates one or more bearings have worn down and should be replaced.
Likewise, if the seals are leaking grease or allow contaminants into the bearings, replacement should be done immediately to prevent further wear. Any time the wheel hub is removed for other repairs, many mechanics will also opt to install fresh bearings as preventive maintenance.
Wheel bearing replacement cost
Wheel bearing replacement cost varies quite a bit based on the year, make and model of vehicle. The labor time and part prices both influence the total bill. Here are some examples of average wheel bearing replacement costs for popular models:
| Vehicle | Parts Cost | Labor Time | Total Cost |
|---|---|---|---|
| Toyota Camry | $150 | 2.2 hours | $450 |
| Honda Civic | $130 | 1.5 hours | $350 |
| Ford F-150 | $175 | 2.5 hours | $500 |
For an older vehicle with simple wheel bearing configurations, total repair costs may be under $300. Newer vehicles with more complex hubs and labor-intensive repair procedures can cost $600 or more.
Can you drive with a bad wheel bearing?
Driving with badly worn or damaged wheel bearings is never recommended. A failed bearing can allow the wheel to wobble or even separate from the vehicle, potentially causing an accident. However, some minor wear is normally not an imminent danger.
If you hear early stage rumbling or growling from a wheel bearing, you can typically continue driving for a short time until it can be repaired. But the noise should diminish when turning one direction which indicates bearing wear. Avoid excessive speeds, hard cornering and large bumps which worsen the damage.
A loud grinding or knocking sound coming from the wheel means the bearings are in the final failure stage and should be fixed immediately. Significant wobble or looseness also means the vehicle shouldn’t be driven at all until repaired.
Steps for replacing wheel bearings
Replacing wheel bearings is not overly complex for mechanics, but does require some specialized tools and knowledge. The basic steps are:
- Lift and support the vehicle safely
- Remove the tire and wheel
- Disconnect brake caliper/rotor if needed for access
- Remove the dust cap, cotter pin, nut and washer from the spindle
- Carefully tap the spindle to separate the hub and bearing assembly
- Thoroughly clean and inspect all hub components
- Press the old bearings out and the new bearings in using a press
- Re-pack the new bearings with high quality grease
- Reinstall the hub, washer, nut, cotter pin and dust cap
- Reinstall brake components and wheel
- Lower vehicle and torque lug nuts to spec
The job can take 1-3 hours per wheel depending on the vehicle. Both inner and outer bearings, seals and races should always be replaced in sets. Allowing the vehicle to sit overnight after greasing allows the grease to properly distribute.
Conclusion
Wheel bearings operate silently and reliably for years before eventually wearing out. Knowing the common causes of premature failure allows you to be proactive about maintenance and early warning signs. This helps avoid more costly repair scenarios. Replacing wheel bearings at recommended intervals ensures you get the full lifespan out of each component.
