There are now many different designs of wheel bearing; single row ball and tapered roller bearings, double row ball (Gen 1), double row tapered roller bearings (Gen 1T) and hub units.
One design not listed above is the FAG Generation 2 bearing, which is fitted as original equipment to many popular modern vehicles, with a growing UK parc numbering more than fifteen million.
The Gen 2 bearing is predominantly fitted to models made by Ford, Land Rover, Mazda, Mitsubishi, Smart, Volkswagen Audi Group, and Volvo.
At first glance the construction appears simple, a pre-assembled unit consisting of a hub flange combined with a Gen 1 bearing. Most of the applications covered by Gen 2 bearings also require an encoder seal to be incorporated into the bearing, which sends a signal to the ECU to allow the activation of on-board safety critical systems such as anti-lock brakes (ABS), traction control (ASR) and electronic stability programmes (ESP).
In the image below you will notice a metal pressing located towards the flange on the bearing. This is a retaining ring which clips into a locating groove in the hub when the bearing is pressed fully home, securing it in place much like a circlip. When the bearing has been fully pressed into the hub it cannot be removed without damaging the retaining ring, so care must be taken to ensure that it is fitted correctly first time.
If you try and fit the bearing by pressing it into the hub using the drive flange you are liable to damage the raceway leading to premature bearing failure and run the risk of the retaining ring not being located correctly. Because of the specific Gen 2 bearing design and the possibility of damage during fitment, specially designed tools are required to mount the bearing correctly.
The special tool consists of a two-piece collar supplied in a range of sizes to suit different Gen 2 bearings. The fitting tool collar sits in the space between the rear of the hub flange and the retaining ring (see the image below). Once fitted the collar allows all of the force applied to be evenly distributed through the outer race when pressing the bearing into the hub (or knuckle). As well as ensuring safe fitment, another major advantage of using the correct tools is that the hub/knuckle does not have to be removed to allow the bearing to be fitted.
Schaeffler Automotive Aftermarket (UK)’s FAG, LuK clutch and INA tensioner brands are supported by technical support and repair installation tips through the RepXpert website (www.RepXpert.com) and a technical hotline; Ireland Tel: +44 (0)1432 264264.