In my 50 years in the auto repair industry, I can’t recall one good story about wheel bearings. Most involve some sort of brake system failure, tires exploding, or fire from a seized red-hot bearing igniting axle grease. Bad wheel bearings should not be ignored.

I’ve replaced hundreds, if not thousands, of wheel bearings. One thing I’ve learned: A bad wheel bearing always gives an indication it’s failing. These include:

Unusual noises coming from the wheels;Poor handling or pulling to one side while driving, cornering or braking;A shaking steering wheel or vibrating vehicle while driving;Uneven tire wear;The anti-lock braking (ABS) dash light comes on.

What Is a Wheel Bearing?

On modern front- and four-wheel-drive cars, wheel bearings are a set of permanently sealed, precisely machined steel ball or straight roller bearings. The balls or rollers are encased in a “cage” that supports the bearings, allowing them to rotate freely.

The cage and rollers are held together inside a hardened metal ring called a “race.” The seal keeps grease in and damaging water and debris out. Wheel bearings are installed inside, and secured to, the suspension, either by press-fit, bolts or a snap-ring. Once mounted, the wheel bearing rides on the axle shaft, allowing the tire/wheel to spin effortlessly.

Wheel bearings allow cars and trucks to run smoother and more efficiently by reducing friction and supporting vehicle weight.

Older rear-wheel-drive cars or trailers use a set of two tapered roller bearings that face each other. These should be routinely serviced every 20,000 miles, or once a year.

Why Do Wheel Bearings Fail?

Under normal driving conditions, wheel bearings should last 85,000 to 100,000 miles. They can fail for several reasons, including:

Low tire pressure: Excess heat from under-inflated tires can shorten bearing life.Road conditions:Hitting a pothole or bouncing off a curb can damage a wheel bearing.Getting in an accident: Any crash that damages the suspension can place undue stress on a wheel bearing.Driving on unbalanced tires or an out of alignment suspension system: Both increase stress on bearings, causing premature wear.Weather: Sub-freezing temperatures, or extended or extremely hot and dry summers, can decrease the effectiveness of wheel bearing lubricants.Failed seals: Once a seal fails and road salts, grit, dirt, dust or water gets into the bearing, failure is only a matter of time.Oversized wheels and tires:These cause increased strain and weight.Improper torquing: Under or over-tightening the axle hub nut can damage bearings.

Do Wheel Bearings Fail One at a Time or All Four at Once?

Unless your vehicle is submerged in a flood, in my experience it’s rare for all four wheel bearings to fail at once.

Can You Fix a Failing Wheel Bearing?

No. Sealed wheel bearings are non-serviceable.

Never reuse any wheel bearing (sealed or tapered) that’s loose, worn, noisy or shows any signs of wear. Trying to fix a loose or damaged wheel bearing can result in an accident and severe injury. Even if a pro suggests repairing a bearing, don’t let them.

Do I Need to Replace the Bearings on Both Axles at the Same Time if Only One Fails?

It depends. Pros disagree on this.

My opinion? If your vehicle has more than 50,000 miles or has been driven in harsh conditions, then it’s logical to replacing wheel bearings on both axles. However, if your vehicle has low mileage and the other bearing is in good condition, replacing only the damaged bearing should not be a problem.

How Much Does Wheel Bearing Replacement Cost?

The average cost to replace a sealed wheel hub bearing is around $350 per wheel. However, depending on the make and model, the shop labor rate ($47 to $215 per hour, according to AAA) and any additional damage could push the cost beyond $1,000 per wheel.

However, on some vehicles, it can be less than $100 per wheel. And you can save hundreds in labor if you DIY. If you don’t have the tools, most auto parts stores will lend you the specialty tools and equipment needed.

NOTE: Whether you DIY or your mechanic replaces the bearing, always install a new axle hub nut. Most hub nuts are prevailing torque fasteners. They’re used on critical components, like securing axle shafts to hub bearings, where a loose nut could lead to disastrous consequences.

Read More