Wheel bearings support the weight of the vehicle and allow the wheels to spin freely with minimal friction. They wear slowly over time, but when they start to fail the symptoms are hard to ignore: growling or humming noises that change with speed, vibration through the steering wheel, and in severe cases wheel play that can cause loss of control. Replacement is an intermediate to advanced DIY job depending on the vehicle design.
Symptoms of a Failing Bearing
A humming, growling, or grinding noise that increases with vehicle speed is the classic bearing symptom. The noise often changes when you turn – if it gets louder when turning left, the right bearing is likely the culprit (turning left loads the right wheel more), and vice versa. Other symptoms include vibration through the steering wheel at highway speeds, uneven tyre wear (especially cupping patterns), and in advanced cases visible wheel play when you grab the tyre at 12 and 6 o’clock positions and rock it. Any wheel play at all indicates immediate replacement is needed.
Bearing Types
Modern vehicles use one of three main bearing designs. Pressed-in bearings sit inside the steering knuckle and require a press or special puller to remove and install – a hard DIY job that many people take to a shop. Hub assemblies (used on most modern front-wheel drive vehicles and many rear axles) come pre-assembled with the bearing inside the hub, and the whole unit unbolts from the knuckle. This is much easier to replace at home. Tapered bearings (common on older rear-wheel drive vehicles and trailer hubs) are serviceable and adjustable, requiring cleaning, repacking with grease, and preload adjustment during installation.
Hub Assembly Replacement
Safely raise and support the vehicle on jack stands with the wheel removed. Remove the brake caliper (support it with wire so it does not hang by the flexible brake hose) and the brake rotor. Disconnect the ABS sensor connector if fitted. On the front, remove the axle nut in the centre of the hub – this is torqued very tightly (200-400 Nm typically) and requires a long breaker bar or impact wrench. Push the axle out of the hub using a hub puller if needed. Remove the hub assembly mounting bolts (usually 3 or 4 bolts on the back of the knuckle) and pull the hub off.
Install the new hub, torquing bolts to specification (typically 100-150 Nm – your workshop manual has the exact value). Reinstall the axle if fitted, and torque the axle nut to specification (often a two-stage torque followed by an angle). Refit the ABS sensor, rotor, caliper, and wheel. Torque the wheel nuts and lower the vehicle.
Pressed-In Bearings
Pressed-in bearings require pressing out the old bearing and pressing in the new one using a hydraulic press or a specialised bearing puller/installer kit. Many DIYers remove the entire steering knuckle and take it to a machine shop for pressing (typically $30-50 per bearing). Doing it in the vehicle requires a specific tool set and significant care – damage to the knuckle or improper pressing angles ruins the new bearing quickly.
Do Both Sides
If one bearing has failed, the other side is likely showing wear too. Many mechanics recommend replacing bearings in pairs (both fronts or both rears) to avoid returning for the same job in a few thousand kilometres. This is especially true on high-mileage vehicles where all bearings are of similar age.
Hub torque specifications, axle nut torque and angle, and bearing types are vehicle-specific. MechanicMate offers PDF workshop manuals for over 960 models at mechanicmate.net/shop.
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