A worn wheel bearing produces a humming, growling, or roaring noise that increases with vehicle speed. Left unattended, a failing bearing can seize or disintegrate, which can cause the wheel to lock up or even separate from the vehicle. Replacing a wheel bearing is an intermediate DIY job that requires some specialised tools but can save significant labour costs compared to a workshop.
Types of Wheel Bearings
There are three main types. Serviceable tapered roller bearings (common on older vehicles and many rear-wheel drive vehicles’ front hubs) can be repacked with grease and adjusted. Sealed hub unit bearings (common on most modern vehicles) are a single assembly containing the bearing, seal, and hub flange that bolts on as one unit. Pressed-in bearings are separate bearings pressed into the steering knuckle, requiring a hydraulic press for replacement. Your workshop manual identifies which type your vehicle uses and the correct replacement procedure.
Confirming the Diagnosis
A wheel bearing noise changes when you turn the steering slightly at speed. Turning left loads the right-side bearing more, so if the noise gets louder when turning left, the right bearing is likely at fault (and vice versa). With the vehicle raised on jack stands, grab the wheel at the 12 and 6 o’clock positions and rock it. Any noticeable play indicates a worn bearing. Spin the wheel by hand and listen for grinding or roughness.
Replacing a Hub Unit Bearing
Hub unit bearings are the most common type on modern vehicles and the most straightforward to replace. Remove the wheel, brake calliper (hang it with wire – never let it hang by the hose), and brake rotor. Disconnect the ABS wheel speed sensor connector if applicable. Remove the hub unit mounting bolts (typically 3 to 5 bolts from behind the knuckle) and the axle nut if applicable. Slide or tap the old hub unit out, install the new one, and torque all fasteners to specification. Reassemble the brakes and wheel.
The axle nut torque on hub unit bearings is critical and often very high (typically 180 to 280 Nm). Under-torquing causes premature bearing failure, and over-torquing can damage the bearing. Your workshop manual lists the exact torque value.
Replacing Pressed-In Bearings
Pressed-in bearings require removing the entire steering knuckle from the vehicle, pressing the old bearing out using a hydraulic press, and pressing the new bearing in. This requires access to a press and the correct bearing driver sizes. If you do not have a press, many auto parts stores or machine shops will press bearings for a small fee. The critical specification here is the interference fit – the bearing must be pressed in straight and fully seated, and the correct snap ring (if used) must be installed.
After Replacement
After bearing replacement, a wheel alignment is recommended as removing the knuckle or hub can disturb the alignment settings. If you disconnected an ABS sensor, clear any stored fault codes with an OBD-II scanner. Test drive at various speeds and confirm the noise is gone and the ABS light is not illuminated.
Bearing type, axle nut torque, hub bolt torque, and ABS sensor details are all vehicle-specific. Your workshop manual covers these for your exact model. MechanicMate offers PDF workshop manuals for over 960 vehicles at mechanicmate.net/shop.
