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Bearing up under the strain

Modern wheel bearings are under more stress than ever, which might explain why they account for 20% of all MOT Test failures. Rob Marshall, therefore, asks Schaeffler’s FAG brand why this is the case and establishes what support is out there for the independent workshop.

While many technicians blame the crumbling state of UK roads as contributing to the premature failure of suspension springs, dampers and tyres, fashion also has a role to play. It was not so long ago that the car-buying public viewed 17-inch rims as exotic but, like BMW front kidney grilles, the situation is becoming almost cartoonish. The craze has seen 21, 22 and even 23-inch alloys becoming the norm – especially when shod with less compliant low-profile tyres. Where will it end?

The situation is bringing technical problems, too. Schaeffler reveals that these larger rim diameters amplify the vibrations and lateral forces that pass through the wheel and into the chassis. In turn, this places additional strain on individual components, wheel bearings included. This consideration is not ignored by the vehicle manufacturers’ engineering department, however. As an OEM supplier, Schaeffler works hand-in-hand with vehicle brands and it reports that its FAG wheel bearings are selected as the original equipment choice of many of the world’s carmakers. The company can, therefore, be believed, when it explains that this is one major reason why its latest third-generation wheel bearing is being adopted at factory level. As the design comprises the complete hub unit, the bearing assembly is much stiffer, making it more tolerant of higher shock loadings.

Quality bearing, or tool suppliers, can provide the tooling you need to install bearings. Pictured are the tools needed to press a Generation 2.1 bearing into position on a Skoda Roomster, which features a snap ring.

Practical and theoretical support…

Like many parts of the motorcar, wheel bearings have evolved, although you can still find first-generation taper bearings fitted to the front wheels of rear-wheel-drive cars. Thankfully, wheel bearing training and information is available for all three generations, so you can identify the types used on a particular car and understand why inappropriate fitting techniques can damage this vital safety component. For instance, Schaeffler’s Repxpert app includes fitting instructions and labour time information. Live technical help is also available on the Repxpert hotline: 0872 737 0037. To be fair, other quality suppliers provide technician back-up, too. For instance, the bilstein group’s Protips include the latest repair information and information on new product lines.

Aside from specialist tools, consider that wheel bearing sockets are also available for hub nuts that are recessed deeply. The bilstein group offers these under its Blueprint brand, part numbers ADT35501, ADG05525 and ADK85503.

Perhaps the most common type you will encounter on a typical UK car is the second-generation bearing. These include the wheel mounting flange, so you renew the entire assembly. Some of these types (notably generation 2.1) require specific installation procedures and special tools so that the bearing can be pressed into position without causing damage. Some types possess a snap ring, too. While these can be pulled clear from the steering knuckle, refitting dictates a special tool that not only ensures

that force is applied only to the outer bearing race but it must also hold the snap ring in position, so it engages evenly within the groove machined into the bearing seat. Schaeffler emphasises that such tools are essential for anybody replacing generation 2.1 bearings, which it can supply if necessary. Some companies, such as MEYLE, offer redesigned Generation 2.1 bearings that can be installed without the need to use special tools but only for certain applications.

Thankfully, third-generation wheel bearings tend to be easier to remove and fit. Thanks to an extra flange, the part bolts into place. However, do not forget the basics, such as noting and applying the correct torque values and using all of the supplied parts within the box. Even so, should you become stuck, it is reassuring that quality suppliers are on hand to support you.

Treat bearings delicately. Dropping one can damage it severely, especially if it contains a magnetic encoder for the wheel speed sensor.

Parts support…

Schaeffler emphasises that it supports the aftermarket with quality bearings, because workshops are supplied with the same parts as those received by car factories. It adds that its ‘complete repair solution’ philosophy means that every single component that is needed to complete a professional wheel bearing replacement task will be supplied, down to the last nut, bolt and washer.

The bilstein group, via its febi and Blue Print brands, also insists on supplying all ancillary parts so that workshops do not have to place multiple orders. The company highlights that it supplies many parts that are separate but related to the wheel bearing. These include the wheel hubs (where applicable) and wheel speed sensors.

The future…

Schaeffler reports that, as high-voltage vehicles (including BEVs) can weigh up to 30% more than a combustion- engined vehicle, current and future bearings must be stronger still – presuming that vehicle weights continue to increase unopposed. Schaeffler reveals that not just bearing design has evolved but also the materials used to make them; even ceramics are tipped as future bearing material for automotive wheel bearings. An interesting development from the company is Trifinity, a new wheel bearing assembly that comprises a trio of angular contact ball bearings. Schaeffler claims that it offers a longer service life, compared with double-row ball bearing designs. Friction is also reduced by over 50%, which contributes positively to OEM fuel consumption/range/CO2 figures.

About Autotechnician
Autotechnician is a magazine published nine times a year, delivering essential information to independent garage owners and technicians in the UK. Delivered both digitally and in print, autotechnician provides readers with technical, training, business advice, product and news, allowing our readers to keep up to date with information they need to run and work within a modern workshop.
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