PeachParts Mercedes-Benz Forum - View Single Post

jay_bob · #45 01-02-2019, 05:13 AM

Just had to replace the bearings on my 2008 E320. Very similar setup to the W124 and W210 (and I’m sure many others).

There is one critical difference between the W211 and the older models however.

On the W124 and W210 there are a series of ridges cast into the outside face of the inner end of the hub. These pass by an inductive sensor in the housing, set perpendicular to the spindle, that counts the ridges to determine wheel speed. On the W124 this is just used for ABS but on the W210 it goes into the computer and used for many things. The sensor is a simple inductive coil that checks for the disturbance of the magnetic field as the ridges go by.

On the W211 they changed the inner grease seal to include a circular ring of magnets embedded in the outer surface, and the inner end of the hub is smooth on the outside. The sensor is now a Hall effect type, that is sitting in the face of the steering knuckle assembly, parallel to the spindle.

When setting the grease seal, it must be perfectly flush with the face of the hub and no deeper. I inadvertently set the first one about 1 mm too deep and it caused ABS/ESP errors because the sensor could not reliably detect the magnets. I put the car on Xentry and drove up and down my street and it was just enough gap to make the data intermittently not OK. $14 and a new seal later and everything is fine. Luckily I did them one at a time so I was able to learn and do the second one correctly the first time.