Attention! The front wheel hub bearing is pressed into the steering knuckle, so when removing it there is a high probability of damage and it may need to be replaced.
Front wheel hub
Removal
Using a screwdriver to remove the protective cap from the front wheel hub
Removal the spring from the hub axle
Loosening the clamp bolt securing the front wheel hub nut
Unscrewing the front wheel hub mounting nut
1. Remove the front brake disc. On models with anti-lock braking system, remove the ABS sensor from the front wheel.
[Original published on the website: MercedesMAN]
2. Using a screwdriver or punch, remove the protective cap located in the center of the front wheel hub. If the protective cap is damaged during removal, it must be replaced (see Fig. Using a screwdriver to remove the protective cap from the front wheel hub).
3. If present, remove the spring from the hub axle (see fig. Removing the spring from the hub axle).
4. Loosen the clamp bolt securing the hub mounting nut from unscrewing, then unscrew the nut and remove it from the hub axle. Remove the thrust washer if present (see fig. Loosening the clamp bolt securing the front wheel hub nut, Unscrewing the front wheel hub nut).
5. Remove the front wheel hub from the steering knuckle. If the hub does not come off, you will need to use a puller.
6. If the inner bearing race remains on the steering knuckle, use a puller to remove it from the hub axle, then remove the hub seal ring.
7. Check the condition of the steering knuckle and replace if necessary.
Repair
1. Remove the inner race of the outer bearing from the hub.
2. From the rear of the hubs, remove the sealing ring and then remove the inner race of the inner bearing. 3. Place the hub on a suitable mandrel and, using a hammer and drift, knock out the inner race of the outer bearing. Do not tilt the race to avoid damaging the bearing seat in the hub.
4. Turn the hub over and knock out the outer race of the inner bearing in the same way.
5. Clean the hub from dirt and grease and, using sandpaper, grind down the burrs on the hub. Check the condition of the hub for cracks, wear and mechanical damage and replace if necessary. On models with an anti-lock system, check the condition of the sensor toothed rotor.
6. Before assembly, apply a thin film of grease to the outer bearing race and the mating surface of the hub. Also lubricate the raceways of the inner race.
7. Mount the hub on the mandrel and install the outer race of the inner bearing into the hub. Using a tubular mandrel resting on the outer race of the bearing and a press, press the bearing race into the hub until it stops. Do not tilt the bearing race when pressing it in.
8. Turn the hub over and press the outer bearing outer race into the hub in the same manner.
9. Install the inner race of the inner bearing. Install the sealing ring on the rear of the hub with the working lips facing the bearing. Fill the bearings with grease to two-thirds of the full volume of grease, then install the inner race of the outer bearing.
Installation
1. Apply a thin coat of grease to the back of the hub seal and install the hub onto the steering knuckle.
2. Install the thrust washer and screw on the hub mounting nut.
3. By tightening the hub mounting nut, press the inner bearing races of the hub onto the steering knuckle journal. After installing the hub, adjust the axial play of the hub bearing. After making the adjustment, tighten the clamp bolt that secures the hub mounting nut from unscrewing.
4. Install the spring onto the steering knuckle pin.
5. Install the protective cap with grease on the hub.
6. Install the brake disc and, if equipped, the front ABS sensor.