When doing any regular vehicle maintenance or if you suspect a wheel bearing issue, they can be inspected. Do the following to check your bearings for wear without taking the wheels off.

Back in the old days, wheel bearings were composed of 2 cone bearings on each front side. When removing the brake rotors (or drums) these more old-fashioned bearings could be serviced by packing the bearings with grease. While some vehicles still retain this style of bearing, it is rare.

A humming or rumbling noise while driving is usually the prime indication of a worn wheel bearing. This sound will get louder if you take the wheel and lightly turn one direction of the other at speed or go on a slight curve in the road at speed. Driving on a damaged wheel bearing can be dangerous, considering that the wheel bearing is not sufficiently lubed and friction is extremely high at this point. This friction generates heat, which will eventually disintegrate the bearing more, when can lead to complete failure, wheel off, or loss of control of the vehicle.  This can occur anytime you are driving.

For this reason, SKF engineers supported re-engineering the expander to use rolling element bearings. In addition to lower running friction, the tight tolerances of rolling bearings allow the screw machines to run with very narrow end gap clearances between screw shafts and housing, which further increases efficiency. Calculations and tests showed that the related energy losses could be substantially reduced, typically from 30 kW to 12 kW, which means that a single expander can produce 18 kW more electricity output when a rolling bearing system is used.

A recently built 250 MW geothermal power plant in Asia is using the organic Rankine cycle (ORC) technology to produce green electric energy from geothermal heat. Almost 200 so-called screw expanders are used to drive the electricity generators. Screw expanders are based on the same mechanical principle as twin-screw compressors, but operate in the “opposite direction” to produce energy from expanding vapour, similar to a steam turbine. A particular engineering challenge was to reach the efficiency targets set by the plant owner. First tests showed that this could not be achieved when using hydrodynamic bearings. Note that five or six hydrodynamic bearings are used in each of the large screw expanders.

Learn the symptoms of a worn wheel hub, common causes, and why early replacement is key to maintaining your vehicle's safety.

Front wheel hub and bearing assemblycost

[2] Vanhaelst R, Kheir A, Czajka J, “A Systematic Analysis of the Friction Losses on Bearings of Modern Turbocharger”, Combustion Engines 1/2016 (164), pages 22–31.

Spin the wheel/tire by hand and listen carefully. You should hear a soft rubbing sound which is just the brake pads gliding over the rotor. A grinding sound centered in the very middle of the wheel is a dead giveaway for a failing wheel bearing. It’s important to note that when wheel bearings first start to go, it will normally be difficult to hear and tell. Usually only a road test under the weight of the vehicle will reveal that the bearing is going out.

The introduction of new environmentally friendly refrigerants (e.g., hydrofluoroolefins (HFO) with low global warming and ozone depletion potential) and the much higher temperature levels needed in heat pumps or data centre chillers often have an unwanted effect: the rate of dilution of the oil by the refrigerants is increased, sometimes up to dilution ratios of 50 % or more. In some cases, the oil viscosity becomes too low for hydrodynamic bearings and the compressors’ bearing arrangement needs to be changed to rolling bearings, which also gives the additional advantage of lower frictional losses and higher impeller positioning accuracy.

Once again, these are all just approximations. However, they are a great indication of what you can anticipate paying. Fortunately, wheel bearings last a long time, so you won’t need to change them very frequently.

Recently, SKF was deeply involved in the design of a new generation of large ammonia screw compressors for chiller and refrigeration applications. The customer, a leader in this field, typically used hydrodynamic journal bearings with relatively large bearing clearance to accommodate the radial loads and angular contact ball bearings for thrust loads. Currently cylindrical roller bearings with tight radial clearance tolerances are piloted as an alternative to hydrodynamic bearings. This improves the volumetric efficiency of the compressor; the oil consumption of the compressor system can also be reduced.

Wheel hub Bearing Assembly

The criticality of energy and resource efficiency, particularly in industrial production and power supply, is on the global agenda as almost never before. Despite technological progress, a lot of energy is still wasted in the world because of mechanical friction and fluid-dynamic losses in rotating machinery, including compressors, turbines, blowers and pumps. Here we show explanations and real-life examples in which considerable energy and cost savings could be obtained by replacing hydrodynamic fluid film bearings with modern rolling element bearings.

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Wheel hub assemblyreplacement cost

Choosing between all-wheel drive (AWD) and front-wheel drive (FWD) depends on your driving needs. Learn the pros, cons, and key factors to decide which drivetrain is best for your car.

SKF solutions and engineering capabilities enable the transition from hydrodynamic fluid film bearings to more efficient rolling bearing systems.

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Popular in German and Japanese vehicles, these units are the sealed roller bearing that you see on the back of the complete unit. In these cases, the entire steering knuckle must often be removed from the vehicle, and the bearing pressed out, and the new one pressed in. While the cost of the bearing drastically diminishes (usually these run between $25.00-50.00) the labor involved to replace the bearing goes up, usually to the tune of 2-4 hours to replace ($160-400.00).

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In the case of most vans and trucks today, along with older RWD cars, the rear wheel bearings are housed inside the solid axle, and are usually pressed into the axle tube, or pressed onto the drive axle itself. In either case, the cost of the bearing is usually between $25.00-50.00, whereas the labor to remove and press in a new bearing runs between 1-4 hours.

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As engineers and enthusiasts for high-performance cars know, ball bearing turbochargers have dominated the motorsport scene since the first ball bearings replaced journal bearings in turbochargers in the 24-hour LeMans races in the 1990s. There were two main reasons for this. Firstly, ball bearing systems showed lower running friction. And secondly, they avoided the need for high-pressure oil pumps that create power losses in journal systems where a lot of oil must be pumped through thin holes in the journal sleeves. Recent designs apply space saving cartridge units with hybrid ceramic ball bearings, taking performance to even higher levels.

Wheel Hub AssemblyKit

[3] Morales G E, Hauleitner R, Wallin H H, “Pure Refrigerant Lubrication Technology in Oil-Free Centrifugal Compressors”, Evolution 2 March 2017.

While you can lower your wheel bearing replacement cost by doing it yourself, be prepared to invest a bit of time into the repair. Experience is among the key elements impacting completion time and the estimates above are based on professional book times, not “I’m doing this for the first time” times. First-timers should expect the job to take around 4-6 hours.

Without getting under the car, grab each wheel at the top and bottom with both hands. You bottom hand should reach under the tire to the backside. Your top hand should grab the front top portion of the tire. Now, try to rock the tire back and forth by pulling outward with the bottom hand, and inward with the top hand, then reversing the motion.

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For thousands of years, mankind has applied rolling elements (bars, rollers, balls) to reduce friction and heat loss in transport and rotating machinery and to provide accurate and reliable positioning of rotating shafts. That is why rolling element bearings are sometimes also called anti-friction bearings or precision bearings. However, for different technical and historical reasons, a lot of “friction bearings” are still used in the world, typically called plain, sliding, journal, fluid film or tilting pad bearings, or more specifically hydrodynamic or hydrostatic bearings.

Wheel bearings live a tough life. Most of a vehicle's weight rides on the wheel bearings at the 4 corners of your vehicle. Once these bearings begin to deteriorate, a humming noise becomes noticeable. It's easiest to hear at speed when you turn the wheel slightly from side to side. When a rear wheel bearing goes out, the humming or grinding noise is usually constant.

Front Wheel Hub Assembly

Rolling element bearings are also often the preferred choice for intermittent operations and cold environments because of their low start-up friction, especially when using hybrid bearings with ceramic rolling elements. But what is more important for energy efficiency is that running friction is usually much lower for rolling element bearings, at least at low and medium speeds. According to a statement from J/E Bearing & Machine Ltd [1], the full fluid film in hydrodynamic plain bearings requires up to three times more energy to operate, even if start-up losses are excluded. The schematic figure below illustrates a typical result when comparing friction (power) losses in journal bearings compared with ball or roller bearings.

Today, aside from rear-wheel drive vehicles that use a solid axle (like trucks), most vehicles use a hub bearing. These consist of a bearing and flange surface that is bolted directly to the steering knuckle or rear transaxle. The bearing then has a hub face, with the wheel studs and tire-mounting surface. Often, an axle (often one with a CV joint) also passes through this bearing via a splined surface and has a large hub nut (called a spindle nut) that secures it at the bearing. This design makes up most bearings on vehicles today. There are some vehicles that still use a pressed-in hub bearing, where you re-use the original wheel hub, but this is becoming rare.

Large commercial or industrial chillers or heat pumps typically engage centrifugal or reciprocating compressors, which compress a refrigerant gas to enable heat transfer from a lower-temperature source to a higher-temperature sink. Traditionally, many refrigerant compressors were or still are gear-driven designs, often comprising hydrodynamic bearings lubricated with an oil-refrigerant mixture.

Front wheel bearing hub Assemblyreplacement cost

The vast majority of vehicles today use a complete-unit hub bearing. Here, the cost of the bearing is usually the bulk of the expense, as most hub bearings run between $80.00 to $300.00. Many of these have ABS sensors built into them. These bearings are unbolted from the steering knuckle, and a new bearing bolted on. Expect to pay for 1-2 hours of labor to replace per side, usually between $80-200.00.

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You can lower your wheel bearing replacement cost by changing them yourself. You should be able to do this in your own garage. However, it will require some specialized tools. Make sure to reference your vehicle’s service manual or seek out online information and determine the kind of wheel bearing your car or truck is geared up with prior to starting the repair work. Keep in mind that AutoZone rents all the specialized tools you will need to replace your wheel bearing and does so for free! Learn more about Loan-A-Tool here.

The data show that rolling bearings create lower bearing friction losses and also lead to lower volumetric seal gap losses due to better running accuracy. A positive effect on efficiency is also attributed to the fact that rolling element bearings require much less oil (typically less than 10 %) for lubrication than hydrodynamic bearings and so less oil is mixing into the refrigerant, leading to lower oil contamination in the heat exchangers. Therefore, chiller efficiency improvements of 3 % to 4 % can be achieved by using oil-lubricated rolling element bearings instead of journal or hydrodynamic bearings. Another major step in improving efficiency may be achieved by designing oil-free chillers, based on either SKF magnetic bearings or SKF Pure Refrigerant Lubricated (PRL) bearing solutions as written in SKF’s Evolving Chiller Performance brochure and in this Evolution article.

Next, if movement is present, inspect the lower ball joint (and upper if applicable) and see if the movement is coming from a worn ball joint. If ball joints are tight, then the wheel bearing is suspect.

Together with some application experts and key customers, data for frictional losses were collected from testing and field experience and consolidated for a typical medium-sized (~300kW) centrifugal chiller (fig. 3). In this comparison, the following types of losses were considered: bearing friction, volumetric sealing gap losses, check valve losses and heat transfer losses due to contamination of the heat exchangers by oil mixing with the refrigerant gas.

With the wheel bearing replacement cost in mind, you may be wondering if you can drive with a bad wheel bearing. A bad wheel bearing needs to be changed as soon as possible. There is no lubrication on a bad wheel bearing. Consequently, as you drive with a bad wheel bearing, you run the risk of the wheel bearing completely failing and breaking apart, which can cause massive stability problems when driving, even a crash. If you’re in the middle of nowhere and you need to drive a short way to get help to prevent this scenario, you should drive at a slower speed so that your wheel remains intact for a couple more hours.

Wheel hub assemblydiagram

Give us a call today or stop by your local AutoZone if you have any questions about wheel bearing replacement, where we have all the parts, tools, and advice to get the job done right! If the job is too big for you, look through our list of Preferred Shops in your area that can help you complete the job!

These vehicles up until very recently still used hub systems that house roller bearings or cone style. While these bearings themselves are often as cheap as 2WD vehicles, the process of removing them and disassembling the hub is often a little more time-intensive. Expect to pay for 1-1.5 hours of labor per side, which is usually $80-160.00, plus the bearings to replace. Keep in mind if the race is damaged in the hub, it will need to be pressed out, and a new race pressed in, leading to more time.

Traditional cone or roller bearings in older 2WD vehicles are often serviced when removing the rotors during a brake job. These bearings can easily be replaced, are less expensive to buy, and generally cost around $6-20.00 per unit, and $80-100.00 to service, along with the cost of replacing the rotor usually, as the bearing race is pressed in. All in, labor and rotor, most vehicles will run around $150.00 to replace and go up depending on rotor cost. In many cases, it’s cheaper to replace the rotor than it is to remove and press in a new bearing race.

However, hydrodynamic bearings have rather large clearances and will suffer from wear and scuffing in frequent start-stop operations or at very low speeds, which can be the case in VFD-driven applications. When the lubricating oil viscosity is low or the oil becomes heavily diluted by the process media, lubricant film build-up may not be sufficient anymore for good performance of hydrodynamic bearings, especially for the thrust tilting pad bearings. In this respect, rolling element bearings are a good alternative as they can operate with lower viscosity lubricants and dilution, especially when ceramic rolling elements are used.

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Wheel hub assemblyparts

Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

Wheel bearings live a tough life. Most of a vehicle's weight rides on the wheel bearings at the 4 corners of your vehicle. Once these bearings begin to deteriorate, a humming noise becomes noticeable. It's easiest to hear at speed when you turn the wheel slightly from side to side. When a rear wheel bearing goes out, the humming or grinding noise is usually constant. Back in the old days, wheel bearings were composed of 2 cone bearings on each front side. When removing the brake rotors (or drums) these more old-fashioned bearings could be serviced by packing the bearings with grease. While some vehicles still retain this style of bearing, it is rare. Today, aside from rear-wheel drive vehicles that use a solid axle (like trucks), most vehicles use a hub bearing. These consist of a bearing and flange surface that is bolted directly to the steering knuckle or rear transaxle. The bearing then has a hub face, with the wheel studs and tire-mounting surface. Often, an axle (often one with a CV joint) also passes through this bearing via a splined surface and has a large hub nut (called a spindle nut) that secures it at the bearing. This design makes up most bearings on vehicles today. There are some vehicles that still use a pressed-in hub bearing, where you re-use the original wheel hub, but this is becoming rare.

Saving 18 kW of power losses can mean more than 100,000 kWh of additional electrical energy output – per machine and per year. Multiplied by the large number of screw expanders used in one plant, this translates into more than a million dollars of additional profit per year.

For industrial equipment such as pumps, compressors and blowers, yearly runtimes of 4,000 to 8,000 hours are quite common, which implies that the electrical energy to drive those machines is usually by far the largest contributor to life cycle cost (LCC) and emissions. In many cases, a powerful means of improving energy efficiency is the use of direct-drive variable speed drives (VFDs), as well as the choice and careful design of the impeller, bearings and sealing system.

Shift back into park (for an automated transmission) or gear (for a manual transmission) prior to lowering the vehicle to the ground.

Hydrodynamic fluid film bearings rely on fluid (oil) films to separate the steel surface of the rotating shaft from the stationary housing support, using the long-known principles of hydrodynamic lubrication. Well-lubricated hydrodynamic bearings show practically no fatigue or mechanical wear, and they provide more fluid film damping than ball or roller bearings. Due to the relatively thick oil film, dirt and other particles have less impact on their performance because hard particles are partly embedded in the softer sleeve or pad materials and thus cannot harm the countersurfaces.

There should be very little motion in the tire. If you have any movement at all, either a wheel bearing, or ball joint is at fault.

Rear wheel bearings today are usually no different than fronts in terms of a complete hub bearing or pressed-on units. In the vast majority of cases here, a complete unit is used and unbolted / bolted to the rear transaxle (2WD vehicles) or independent rear axle.