Audi A4 (B6): Front Wheel Bearing Replacement

Part numbers are from the manufacturer's original catalogue. Check them against your VIN before ordering.

• jack and jack stands
• lug wrench
• torque wrench
• 17/18/19 mm sockets and 30-36 mm socket for the CV axle nut
• Torx and triple square (XZN) set
• ball joint separator or small sledgehammer
• brass drift
• hydraulic press or wheel bearing press kit (if the bearing is pressed in)
• snap ring pliers
• wire for hanging the caliper
• penetrating oil
• copper grease

1. Identify the noisy side: while driving, steer gently from side to side. The hum gets louder when the load shifts onto the affected bearing. Then lift the wheel off the ground and rock it up-down and left-right: play and a rumbling feel when you spin it confirm wear.
2. Park the car on level ground, apply the parking brake and chock the rear wheels. Loosen the wheel bolts half a turn and the hub nut (CV axle nut) 1-2 turns. Do this with the wheel on the ground and a helper pressing the brake pedal.
3. Raise the front of the car with a jack, set jack stands, and remove the wheel.
4. Fully remove the hub nut. On this car the nut is single-use and must be replaced.
5. Remove the two bolts holding the caliper bracket to the steering knuckle, take off the caliper together with the bracket and hang it on wire so the brake hose does not carry its weight.
6. Remove the brake rotor (if needed, take out the retaining screw and tap the rotor lightly with a hammer through a spacer).
7. Remove the ABS sensor from the knuckle (one bolt or screw) and set it aside. Clean the sensor seat before reinstalling.
8. Release the tie rod end from the knuckle arm and the ball joint from the lower control arm (remove the nuts, then press out the pins with a separator). If needed, disconnect the sway bar link. The fastener locations depend on the suspension version.
9. Push the drive axle out of the hub with light taps through a brass drift. If the axle is stuck, use a puller. Swing the knuckle outward and move the axle aside without stretching the inner CV joint (the CV joint must stay at a normal angle).
10. Remove the steering knuckle from the strut (remove the bolts that attach it to the shock absorber strut) and move it to a workbench or vise. If the design allows, you can press the bearing out without removing the knuckle, but in practice it is more reliable on a bench.
11. Determine the assembly type. If the bearing is pressed into the knuckle: remove the inner retaining ring with snap ring pliers, press the hub out of the bearing, then press the bearing itself out of the knuckle. If the assembly is bolted on: remove the hub mounting bolts from the back of the knuckle and take off the whole unit, replacing it with a new complete assembly.
12. Thoroughly clean the bore in the knuckle of corrosion and dirt, and apply a thin layer of grease. Press the new bearing in by the outer race only (do not push on the inner race) until it seats fully, then install the new retaining ring. When pressing in the hub, support the inner race of the bearing so you do not damage the balls.
13. Reassemble in reverse order: knuckle onto the strut, ball joint, tie rod end, axle into the hub, ABS sensor, rotor, caliper.
14. Tightening (values are approximate; check the exact values for your car in the manufacturer's specifications): hub nut with a new nut, about 200 N·m (148 lb-ft) plus an additional turn of about 90°; wheel bolts 120 N·m (89 lb-ft); caliper bracket bolts, about 170-200 N·m (125-148 lb-ft) (use new bolts only if they are single-use); bearing or hub bolts to the knuckle, ball joint and tie rod end, per specification, usually in the range of 40-100 N·m (30-74 lb-ft); ABS sensor screw, low torque, about 8-10 N·m (6-7 lb-ft).
15. Tighten the hub nut with the wheel on the ground. Install the wheel, lower the car, and do the final tightening of the wheel bolts with a torque wrench in a crisscross pattern.
16. Pump the brake pedal until the pads seat, check for noise, wobble and ABS faults, and on a test drive listen for a hum at 50-90 km/h.
17. It is advisable to check the wheel alignment (toe) and adjust it if necessary: removing the tie rod and ball joint may have shifted it.

• This assembly directly affects safety: an incorrectly tightened hub nut or caliper can lead to loss of a wheel or brake failure
• If you have no experience with press work and no torque tools, leave the job to a repair shop
• Replace bearings as a pair only if both are worn, but do inspect the other side too
• Do not strike the bearing or press on it through the balls: it will be ruined before it is installed