Front Steering Knuckle: Service and Repair

Fig. 1 Hub, Knuckle & Bearing Replacement:

Fig. 2 Servicing Hub, Knuckle & Bearing:

Replace hub, knuckle and bearing in numbered sequence shown in Fig. 1 and 2, noting following:
1. Remove caliper and suspend with wire, then remove driveshaft nut using end yoke holder, tool No. MB990767-01, or equivalent.
2. Disconnect ball joint and tie rod end using steering linkage puller, tool No. MB990635-01, or equivalent. Loosen but do not remove ball joint and tie rod end nuts until knuckle is ready to be removed.
3. Using a suitable axle shaft puller, press driveshaft from front hub.

Fig. 3 Driveshaft Nut & Washer Installation:

4. Ensure driveshaft nut and washer are installed in direction shown in Fig. 3.

Fig. 4 Speed Sensor Pole Piece Clearance Check:

5. Temporarily install speed sensor to knuckle, if equipped, then insert a suitable thickness gauge between sensor pole piece and rotor toothed surface, Fig. 4, and tighten speed sensor at a position where clearance is 0.012-0.035 inch. If clearance cannot be obtained, check for improper installation of rotor.
6. Remove hub by attaching front hub remover/installer, tool No. MB990998-01 and knuckle arm bridge, tool No. MB991355, or equivalent, to knuckle and hub. Secure knuckle in vise, then tighten nut of front hub remover/installer to remove hub, or hub and rotor from knuckle.
7. Remove wheel bearing inner race from front hub using side bearing puller, tool No. MB990810-01, or equivalent. First, crush oil seal in two places to allow tabs of side bearing puller clearance to get under inner race.
8. Drive wheel bearing out using knuckle arm bridge, tool No. MB991355 remover/installer disc, tool No. MB990932-01 and handle, tool No. MB990938-01, or equivalent.
9. Fill wheel bearing with multi-purpose grease and apply a thin coating to knuckle and bearing contact surfaces, then press in wheel bearing using rear suspension bushing base, tool No. MB990890-01 and rear suspension arbor, tool No. MB990883-01, or equivalent.
10. Drive oil seal into knuckle using lower arm bushing arbor, tool No.MB990947-01 and rear suspension bushing base, tool No. MB990847-01, or equivalent. Apply multi-purpose grease to lip of oil seal and surfaces of oil seal which contact front hub.
11. Use front hub remover/installer, tool No. MB990998-01, or equivalent, to mount hub, or hub and rotor onto knuckle. Torque nut of hub remover/installer to 145-188 ft. lbs. while rotating hub to seat bearing. Leave hub remover/installer in place while taking measurements described in Steps 12 and 13.
12. Measure wheel bearing starting torque using hub remover/installer and a suitable inch pound torque wrench. Starting torque must be 16 inch lbs. or less and bearing must not feel rough when rotated.
13. Measure hub endplay using hub remover/installer and a suitable dial indicator, endplay must be within 0.002 inch. If starting torque and endplay are not within limits specified, bearing, hub and/or knuckle may have been incorrectly installed. Repeat disassembly and assembly procedures.
14. Apply multi-purpose grease to lip and install driveshaft side oil seal into knuckle using rear suspension bushing base, tool No. MB990890-01 and rear suspension arbor, tool No. MB990883-01, or equivalent. Drive seal in until it contacts snap ring.