Auto Service World
Feature   November 1, 2013   by Steve Pawlett

Hub Bearings: Expanding Market Opportunities

There are few repairs where the inferior quality of the parts can become apparent to the customer in a more dramatic fashion than with hub bearing replacement: front-end noise and vibration is very disturbing to drivers. The customer’s annoyance will likely be directed at the shop that installed the hubs, because they naturally expect the shop to steer them in the right direction when it comes to quality components.

By recommending quality wheel hub bearings, jobbers can avoid these comeback nightmares. Given the growth of the aging car park “sweet spot,” there is ample opportunity for market growth in this category – by stocking and selling premium name-brand bearings and wheel hubs, and educating customers on the importance of preventative maintenance using quality components.

The Automotive Aftermarket Suppliers Association (AASA) recently launched a new marketing campaign as a part of its successful “Know Your Parts” program that focuses on the hub bearing category.

“Customers who avoid or delay maintaining their vehicles pose a potential safety risk to themselves, their families, and everyone travelling on roads and highways,” says AASA president and CEO Bill Long. “AASA strongly supports addressing the issue of unperformed/underperformed maintenance through continued consumer education and reasonable, safety-friendly, and cost-effective vehicle inspection programs.”

The hub bearing campaign is the first in a series of category-specific campaigns designed to educate technicians, shop owners, service writers, and other industry repair professionals on the value of installing only quality premium parts. The campaign is funded and sponsored by AASA and member hub bearing suppliers SKF, Timken, NTN, Federal Mogul (Moog), Schaeffler (FAG), and Brake Parts Inc. (Raybestos).

The new campaign kicked off in October and will run for three months. It will be multi-channel with a dedicated micro website, print ads in targeted trade publications, digital banner ads, a fully mobile optimized site, a strong social component, and major presence at AAPEX.

The site features unique articles, graphics, and videos as well as informative content from sponsor companies. All of the content educates the repair professional audience on the benefits of installing only quality hub bearings. Those benefits include durability, proper ABS function, and elimination of noise and vibration in vehicle operation.

“We’ve had success with the Know Your Parts campaign to date,” says Bill Hanvey, AASA vice-president, programs and member services. “It is was time, however, for us to take the message to the next level and provide service providers and consumers alike a resource that provides the information they need to make an informed product decision.”

Along with the launch of the new hubs campaign, AASA has refreshed and re-launched the Know Your Parts site. The refreshed site features a video player and will be mobile-friendly. In addition, the association plans to increase social marketing efforts for the program.

“In 2012, unperformed and underperformed maintenance in the U.S. totalled $66 billion,” says Paul McCarthy, AASA vice-president of industry analysis, planning, and member services. “Although unperformed maintenance has declined by approximately $1 billion year over year, it remains near a record high.”

There is potential good news for future aftermarket growth, McCarthy explains. “Stronger economic growth and increased employment could reduce the cyclical component of unperformed maintenance, reducing the total and helping the industry continue to grow.”

Lower quality hubs can cause excessive front-end noise and vibration. There are several reasons for this, but primarily, it is caused by a lesser hub design and the use of heavier components. This saves money initially, but can be very costly for the shop that loses a customer due to annoying clicking noises or excessive front-end vibration.

In addition to heavier components, value-grade hubs generally use lower-quality steel for their bearings. This often leads to bearing raceway spalling at as little as 1,600 km of driving. This can cause the hub noise and vibration that can drive customers away for good.

Inferior steel will cause raceway spalling, creating noise and vibration in the wheel. A wheel bearing out of adjustment can reduce bearing life and can affect more than just the bearing: it affects the operation and service life of the spindle, wheel seal, and brake components. It is important to adjust the wheel bearing end play to the proper specifications. If the bearing set is adjusted too loose or too tight, it can cause the bearing to fail prematurely.

The hub is directly affected by the condition of the bearing. The driver may first notice a noise coming from the wheel of the vehicle when the steering wheel is turned. There will be noticeable end play when the wheel is unloaded. A check using a dial indicator will show an end play greater than 0.100 mm (0.004 inch). Bearing end play can also affect a wheel speed sensor and cause an intermittent ABS trouble code. If the bearing flange has a runout, that runout will be magnified at the rotor friction surface. A runout of 0.00254 mm (0.0005 inch) at the bearing flange could result in a 0.0025 mm (0.001 inch) runout at the rotor friction surface.

The wheel bearing is the most critical component of the braking system. It positions the wheel and rotor to the caliper, the wheel and drum to the backing plate, and controls the input to the wheel speed sensor. As electronic stability control (ESC) braking systems become more complex, the wheel bearing will still be the central component to the system’s operation. With the introduction of the electronic wedge brake (EWB) just around the corner, the caliper, wheel speed sensor, and chassis controller will become the ABS system. These changes will require greater care in the servicing of the total suspension system.

To avoid comeback headaches, jobbers should always carry a wide selection of quality bearings and hubs. Refresh your knowledge on hub bearings by visiting the AASA site for the Hub Bearings campaign at:

Signs Of A Worn Wheel Hub Bearing


igns of a worn wheel hub bearing vary in severity. Some may be difficult to detect, leading to damage before corrective action can be taken. The time frame in which damage occurs is linked to driving conditions and/or the mechanical practices that were followed at installation. Noise is a classic sign of a bad wheel bearing or wheel hub bearing. Here are some indicators of a worn wheel hub bearing or other wheel-end damage:

• Snapping, clicking, or popping.

This can indicate a worn or damaged outer CV-joint. However, it also can be related to excessive bearing endplay, usually associated with inadequate clamping. This noise is typically heard when cornering or making sharp turns.

• Grinding when the vehicle is in motion.

Typically, this means there is mechanical damage in a wheel-end system. Related to a bearing, it means a loss of integrity such as roller or raceway damage. The noise is normally heard when turning or when there is a shift in load.

• Knocking or clunking.

This can signal excessive play in the CV-joints or U-joints. It also can be caused by excessive backlash in the differential gears. This is not generally associated with bearings and is normally heard either when shifting from changing directions, such as from forward to reverse or transitioning from accelerating to coasting.

• Humming, rumbling, or growling.

These noises are normally associated with tire, electrical, or drivetrain components. If bearing-related, the noise or vibration is present when driving in a straight line, but intensifies when turning the steering wheel slightly to the left or right. Typically, the side opposite the rumbling is the defective side.

• Wheel vibration and/or wobble.

This is generally associated with a damaged or worn tire, wheel or suspension component, or severe chassis misalignment. When related to the hub or bearing, this normally indicates the loss of clamp or a bearing with extreme mechanical damage. It also can occur when lug nuts are not properly torqued.

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