NHBB can provide reliable bearing life estimates based on semiempirical data to assist in accurately forecasting bearing life.

The wheel bearing on a wheel usually consists of a pair bearing assemblies running side by side on the shaft or spindle – this keeps the spindle running straight, while a single row of balls or rollers might allow the wheel to wobble. Exceptions would be the non-tapered roller bearings on rear wheel drive vehicles, which will have only one bearing assembly at the wheel end of the axle, but the inboard end of the axle on those units is splined to the differential assembly, which is spinning in its own set of tapered roller bearings.

Consult the table below for determining values X, Y and e. In all series, the rotational factor V is 1.0 for inner ring rotation and 1.2 for outer ring rotation with respect to load. The factor e (last column) represents the ratio of Fa/VFr for which the two equations are equal. If the ratio of loads is such that Fa/VFr ≤ e, then formula (a) is used; if Fa/VFr > e, then formula (b) is used.

Is your ABS light on, and you do not know what is causing it? A faulty wheel bearing can be a possibility. On some vehicles, the ABS sensor or encoder ring is integrated into the wheel hub and bearing assembly. As such, a failure of the wheel bearing can trigger the ABS light.

Wheel bearing what is itmade of

More often than not, bearings with primarily radial loads are subject to some axial forces. When the magnitude of the axial component of the load is greater than a negligible value, it is helpful to translate the combined radial and axial load into a radial load so that the basic life equation may be used. This radial load, known as the equivalent radial load, is defined as that constant stationary radial load which, if applied to a rotating inner ring, would give the same life as that which the bearing will attain under the actual conditions of load and rotation. For conventional bearing types other than those with filling notches, the equivalent radial loads are given by the maximum of the two values where:

The Basic Load Rating (C) for a radial or angular contact ball bearing is a calculated constant radial load which a bearing with a stationary outer ring can theoretically endure for a rating life of 1,000,000 revolutions of the inner ring. The ratings shown in this catalog are defined by ANSI/ABMA Standard 9 and Standard 11. The ratings for noncatalog bearings may be determined by referring to this standard.

The conventional rating life often has to be modified as a consequence of application abnormalities. The following conditions all have the practical effect of modifying the ideal theoretical rating life of L10:

A static load is a load acting on a nonrotating bearing. Experience shows that a total permanent deformation of 0.0001 of the rolling element diameter, at the center of the most heavily loaded rolling element/raceway contact, can be tolerated in most bearing applications without the bearing operation being impaired. The basic static load rating is, therefore, that load which produces the above deformation. As with the dynamic load ratings, the static rating determinations can be found in ANSI/ABMA Standard 9 and Standard 11.

Since the wheel bearings keep the wheel and hub assembly spinning on an axis, if the wheel bearing is compromised to the point that it can no longer maintain that axis, driving with a faulty bearing can be extremely dangerous—especially at high speeds. Think about a wheel that starts wobbling because the bearing decided to completely come apart while you’re in freeway traffic. This can happen without warning if you’ve become accustomed to the bearing’s noise as it continues to warn you by getting louder.

Certain materials are proven to have greater fatigue life than others operating under identical conditions. The theoretical L10 dynamic life is based on air-melt steel and standard ABMA formulas. The life adjustment factors for materials frequently used are shown here:

In the event that this happens under weather conditions that make the road slippery, immediately maneuver your vehicle to the nearest safe spot off the road.

a. Vibration and/or shock-impact loadsb. Angular misalignmentc. High speedd. Operating at elevated temperaturese. Lubricant effects

Below we define the terms basic dynamic load rating, static load rating, rating life, and reliability. We also provide the basic equations for calculating life and equivalent radial load, plus information about life adjustment, material factor, and other life adjustment factors.

Some may say that you can drive for up to a thousand miles with a failed wheel bearing—but the thing is, this is an arbitrary claim. There’s really no telling how long you can safely drive your vehicle in this state. It would depend on the severity of the damage to your wheel bearing, present road conditions, and other factors. So, it’s best not to push your luck.

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

The standard value L10 equals the total number of revolutions that 90% of a group of identical bearings will theoretically meet or exceed. For a single bearing, L10 also refers to the life associated with 90% reliability. The life which 50% of the group of bearings will meet or exceed (median life, or L50) is usually no greater than five times the rating life (refer to the table under Life Adjustment Factors).

One tricky thing about wheel bearing noise is that a bad tire can make almost exactly the same noise as a bad bearing; you don’t want to replace a wheel bearing for a noise concern when all you need is a new tire.

By now, you may have an idea of how important wheel bearings are. Thankfully, there are signs that can indicate that your wheel bearings are going bad.

Frontwheel bearingnoise symptoms

Note by Richard McCuistian, ASE-certified mechanic: I have personally seen a Crown Victoria that was making a noise I would have sworn was coming from the left rear axle bearing, but after removing and inspecting that bearing (which is difficult on a rear wheel drive vehicle), I discovered that the noise was actually originating from the left front tire. And I had nearly 40 years of automotive experience at the time.

Wheel bearingsymptoms

L (cycles) = Cycles (x 1 million)C = Dynamic load ratingPr = Equivalent radial loada1 = Reliability adjustment factora2 = Material adjustment factorN = rpm

Average life ofwheelbearings

It’s this abnormal sound that’s the most obvious sign something is wrong with your wheel bearings. Of course, because other issues, such as cupped tires, can mimic a bad wheel bearing, you’ll want to diagnose the sound properly.

Wheel bearing noise coincides with the rotation of the tires. The sound typically increases with vehicle speed as well. In some instances, the noise may also change when you turn the steering wheel in one direction or the other.

We use cookies to analyze our traffic. We also share information about you to our analytics partners who may combine it with other information that you've provided to them or that they've collected from your use of their services.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication. Read our full disclaimer here.

A faulty wheel bearing can cause your vehicle to pull to one side during braking. This symptom can also be related to faulty brake components.

New Hampshire Ball Bearings, Inc. (NHBB) is a leading manufacturer of precision bearings and complex bearing assemblies for the global aerospace, defense, medical, and high technology markets. The company is a subsidiary of MinebeaMitsumi Inc. and an integral part of the global brand, MinebeaMitsumi Aerospace.

How to tell whichwheel bearing isbad while driving

When a more conservative approach than conventional rating life (L10) is desired, the ABMA offers a means for such estimates. The table below provides selected multipliers for calculating failure rates down to 1% (L1).

Modern vehicles have sealed wheel bearings that cannot be disassembled without destroying the wheel bearing assembly in the process, and on vehicles with bearings like those, you only know a bearing is bad when it begins to make noise. That’s the earliest indication of a bad wheel bearing, and front wheel bearings (both on front wheel drive as well as rear wheel drive vehicles) are the most prone to fail on modern vehicles.

Additional nomenclature is as follows:– Z is the number of balls– D is the ball diameter in inchesValues of X, Y and e for load or contact angle other than shown are obtained by linear interpolation.

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Wheel bearingreplacement cost

Also, by replacing a bad bearing early on, you can also save yourself a lot of money by avoiding possible major repairs.

If the seal that is part of the bearing fails, moisture and dirt can enter the bearing’s grease, compromising the grease’s ability to keep the load bearing elements (balls and races) lubricated. But there are times when a bearing destroys itself even though the grease is not compromised. Tiny particles of metal can begin to flake off of the races, and when this happens, those particles mix with the grease so that it becomes a grinding compound of sorts, creating a “snowball” effect whereby more metal flakes off and enters the grease charge and the bearing gets noisier with time.

In cases like that, or when you just decide to keep driving until the failure is complete, the bearing itself will decide for you when it must be changed, and it can do so in very unpleasant ways and never at a good time. In other words, there are instances, when left unattended to, a faulty wheel bearing can create hazardous conditions, such as the following:

Loose wheel bearings can throw your car’s alignment off, leading to abnormal tire wear. There are, of course, many other problems that can create the same, undesirable results.  So, you’ll want to diagnose the issue thoroughly before condemning one or more of the wheel bearings

Once again, there are other issues besides a bad wheel bearing that can cause steering wheel vibrations. A thorough diagnosis is needed to verify the cause of the concern.

Wheel bearing what is iton a car

A bad wheel bearing can cause the brake rotor to wobble, which shoves the caliper piston back into its bore so that when you apply the brakes, you have unexpected pedal travel as a result – making it harder to stop or causing the vehicle to pull unexpectedly to one side – never a good thing in traffic.

Bearing fatigue life is a baseline estimate of the number of revolutions or hours that a bearing will operate before failing. The principal factor at play is metal fatigue, so failure is defined by the presence of spalling or flaking on a bearing’s raceways. Since, in reality, identical bearings operating under identical conditions fail at unpredictable intervals, and since there is no way to predict the actual life of a specific bearing, the industry utilizes a statistical formula to calculate rating life. The calculations shown below involve many parameters and are based on historical test data.

Mechanics will find a safe, empty, smooth paved road, then listen carefully to the noise while swerving gently from side to side – typically when you swerve to the right, you’re increasing the load on the left side bearings, and vice versa. And again, while this is a good practice, it’s easy to be fooled into replacing the wrong bearing, even using this method – that’s why some tire shops replace bearings in pairs. If you use this method and believe the noise is tire related, you can move the front tires to the rear and see if the noise changes.

Wheel bearings support the weight of the vehicle and allow the wheel/tire assembly to rotate when you’re traveling down the road. All four of your car’s wheels have wheel bearings and they are designed to last the life of the vehicle. In fact, many vehicles will travel hundreds of thousands of miles/kilometers and never need a wheel bearing replacement, but others may need one or more wheel bearings replaced over their lifetime.

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

When you’re driving with the music cranked up, you may not notice the different sounds that your vehicle makes. But the moment you turn the radio off and notice a growling, humming, or rumbling noise coming from your wheel bearing, you’ll know there’s a problem.

I have personally seen a Crown Victoria that was making a noise I would have sworn was coming from the left rear axle bearing, but after removing and inspecting that bearing (which is difficult on a rear wheel drive vehicle), I discovered that the noise was actually originating from the left front tire. And I had nearly 40 years of automotive experience at the time.

There are different kinds of wheel bearings depending on the year model and the design of the vehicle. Older rear wheel drive vehicles had cone type wheel bearings on the front wheels that could be removed, inspected, and packed with grease, and reinstalled with new seals. Some front-wheel drive vehicles have wheel bearings of this type on the rear. In other words, if a vehicle has cone-type bearings that can be removed, inspected, and repacked, it will always be on the NON-driving wheels – the ones that don’t propel the vehicle. Trailer wheels often have bearings of this type.

If your wheel bearing goes out while you’re on the road, it’s not advisable to keep driving. However, if there’s absolutely no alternative, make sure to maintain a slow and steady pace—do not accelerate or turn suddenly.

Wheel bearing what is itused for

Thank for pointing out that typo. The paragraph was supposed to read: Some front-wheel drive vehicles have wheel bearings of this type on the rear. We have updated the article.

Wheel bearing failure is a potentially dangerous situation at any time, so have your vehicle towed to the nearest mechanic and have your faulty wheel bearings replaced right away. Vehicle safety should always come first.

This paragraph doesn’t make sense: Older rear wheel drive vehicles had cone type wheel bearings on the front wheels that could be removed, inspected, and packed with grease, and reinstalled with new seals. Some rear wheel drive vehicles have wheel bearings of this type on the rear. In other words, if a vehicle has cone-type bearings that can be removed, inspected, and repacked, it will always be on the NON-driving wheels – the ones that don’t propel the vehicle.

Wheel bearings are in a hostile environment and are working very hard, but wheel bearings are very tough – they’re designed for the work they do. But product variability is a real thing, and again, some bearings fail while others never do.

You might have seen a vehicle pulling trailer that has had the bearings neglected to the point that the wheel gets hot enough to set the tire on fire – it can happen on your vehicle in extreme cases, but it’s rare.

Can your car still run with a faulty bearing? The technical answer might be yes; some wheel bearings might continue to operate normally despite the vehicle being driven with one or more noisy bearings for a very long time. The problem is that since the noise begins gradually and slowly gets worse, you might not even notice the noise if your vehicle is noisy in other ways.

Pro Tip: If a noise happens after the tires are rotated on a front wheel drive vehicle, it may be due to the wear pattern on the tires, so be aware of that, too.

A faulty wheel hub and bearing assembly can also cause a vibration felt in the steering wheel. Often, the sensation will change with vehicle speed or while the vehicle is cornering.

It’s worth noting that tire noise will usually change depending on the road surface. Wheel bearing noise, on the other hand, is consistent regardless of road surface and acceleration.

A worn-out wheel bearing may also make a high-pitched squealing sound while you’re driving. If you are able to observe these symptoms, have your vehicle checked right away. Even if your wheel bearings are not the culprit—there’s definitely something wrong with your vehicle.

The older style cone shaped bearings have a series of tapered rollers in a cage with a window for each roller to keep them evenly spaced while they ride between inner and outer races. But most modern sealed bearings have steel balls with inside and outside races.

The load ratings for NHBB precision ball and cylindrical roller bearings are based on ANSI/ABMA Standards 9 and 11. These standards specify the accepted methods for calculating load ratings and fatigue life of ball and cylindrical roller bearings. Since a multitude of variables may affect these calculations, they should be used for baseline estimates only. Load ratings for your application’s specific operating conditions should be calculated before making a final bearing choice.

Another tricky element of wheel bearing noise is the need to pinpoint which wheel bearing is making the noise. Sometimes even professional mechanics will struggle with this, and there are special listening devices shops use to pinpoint which bearing is making the noise. Some tire shops will replace both front bearings if there is a bearing noise coming from the front of the vehicle; not a bad practice, actually.

Remember, the wheel bearing not only allows the wheel/tire assembly to rotate along with the hub the wheel is bolted to, the bearing also carries the weight of the vehicle and maintains the spinning wheel’s axis by keeping it in a straight line. A failed wheel bearing won’t usually allow the wheel to come off completely unless the bearing has become so hot that the axle or spindle is glowing red. Not only can this cause a fire in the wheel well area, the wheel and hub can separate from the vehicle and… well, finish the thought. Granted, this is a very extreme case of a wheel bearing failure, but wheel bearings that have lost their grease can get extremely hot.