WIS 33.00 Wheel Bearings Front Axle
Description - Wheel Bearings Front Axle
The next diagram shows the ABS slotted disc (also called a tone ring) and the hub seal.
Issues - Wheel Bearings Front Axle
- Bad bearings- need replacement
- Loose bearing nut, need adjustment
- Repacking of bearings
Part Numbers - Wheel Bearings Front Axle
These numbers are for a W220 2003 update S500L EU spec.
- Outer wheel bearing: A0029806502
- Inner wheel bearing: A1409810305
Hub seal and ABS Wheel Speed Slotted Disc (ABS Tone Ring):
- A0229979747 (OE) - EUR 40
- FEBI BILSTEIN 24994 - EUR 3
Bearing kits:
- SNR R151.35 - EUR 25
WARNING - Use of Aftermarket Inner Wheel Bearings Front Axle
WARNING: Do not use aftermarket inner bearings without carefully checking that they perfectly match a genuine M-B bearing.
In particular notice the shape of the inner shoulder on the inner bearing on the side that is in contact with the axle back flange. Genuine M-B bearings have a small radiused shoulder. Some aftermarket bearings have a square shoulder. (The next diagram shows a complete but good M-B inner bearing compared with aq bad inner bearing. Only the race is shown as the bad bearing had to be destroyed by being ground with an angle grinder to produce a wafer thin section to allow it to be removed. See scorch mark where the split occurred.)
The radiused shoulder on the inner bearing fits neatly against the radiused edge on the axle flange. If an inner bearing with a square edge is used it will interfere with this radiused edge and the hub will not be in the correct position. The area of interference is shown in the next diagram.
The consequence of using an inner bearing with a square shoulder is that the wheel hub sits slightly proud by about 1mm to 2mm when installed on the axle. This also means that the clearance between the ABS tone ring and the ABS magnetic sensor is increased by the same amount and causes the speed reading sesnor to not work at all or not work properly. The magnetic sensor needs to be in very close proximity to the slotted ABS tone ring to generate adequate speed signals.
If the car is driven with this situation, after a few minutes, the instrument cluster will show ESP Failure and ABS Failure messages along with Drive to the nearest workshop being indicated.
If the gap is too wide, analysis with Star DAS will show that there is zero or an “implausible” speed signal generated by the front wheel ABS sensor.
The fix is to use genuine inner wheel bearings for the front wheels.
VIDEO - Removal and installation of races, bearings, seal; packing and adjustment
Replace inner/outer races, bearings; and seal ring
This video shows how to replace both bearings and races, the seal ring; how to pack the bearings with grease; and finally how to adjust the axle nut play to exact Mercedes specifications.
Complete Front Wheel Hub Re-haul
The video shows part numbers, and prices as of March 2021.