Removal, installation and checking front wheel bearings (Mercedes-Benz S-Class W126)

Note: If noise is heard from the outer surface of the wheel when making sharp turns, this indicates a defect in the wheel bearings.

Caution: The separators and outer races of the wheel bearings must be laid out in the order they were removed so as not to mix them up during installation.

Remove the brake caliper and hang it aside so it doesn't get in the way. Pry the hub cap off with a screwdriver and remove it. Remove the contact spring, loosen the bolt and unscrew the nut that secures the hub to the steering knuckle.

Remove the front part of the hub together with the brake disc from the steering knuckle.

Caution: Be careful not to let the outer wheel bearing fall out.

Remove the brake disc.

Using an aluminum or brass punch, carefully push out the outer wheel bearing support ring, making sure that it runs straight.

Caution: The beard must be made of soft metal and not damaged so as not to damage the ring or its socket.

Using a hex key attachment, drive out the inner bearing support ring. If you don't have an attachment, you can use a punch, but try not to damage the ring.

Examination

Inspect the surface of the steering knuckle, particularly where the seal is installed. Replace the steering knuckle if necessary.

Thoroughly clean the inside of the tapered roller bearings and the hub. It is recommended to use a special cleaning solution. Check the condition of the bearing seats in the hub.

Inspect the bearing support rings in the hub for scratches. The ring is considered to be in good condition if it has a smooth gray track from a working roller bearing.

If the rings are dented by bearings, or if the races are light brown to blue in color due to overheating, the bearings must be replaced.

Check the condition and freedom of rotation of the roller bearings. The presence of rust on the bearing usually indicates a defective seal. Rusty wheel bearings must be replaced.

Caution: Always replace both hub bearings. When reinstalling old bearings, be careful not to mix up the separators and outer races.

Carefully install the bearing support rings into place, ensuring that they are seated correctly.

Apply 45 g of high-temperature roller bearing grease to the hub and bearings. Apply grease to the separators so that it fills the gaps between the rollers.

Install the separators into the hub and lubricate the front ends of the rollers.



Fill the gap between the edges of the new seal with grease and apply sealant to its outer edges (for example Curil). Drive the seal into its place in the hub using a piece of pipe of a suitable diameter.

Fill the front of the hub with the remaining grease.

Caution: If too much grease is added, it may overheat while driving and lose its lubricating properties. If too little grease is added, proper lubrication of the wheel bearings is not guaranteed.

Install the brake disc and caliper in place.