Knuckle/Spindle - Front

This procedure covers the removal and replacement of the front steering knuckle/spindle assembly on a 2007-2013 Mercedes-Benz S65 AMG, including disconnection of suspension components, brake components, and wheel bearing housing.

Warnings

Tools required

Parts

• Front steering knuckle assembly × 1 — Use OEM specification
• Ball joint nut (if reuse not recommended) × 1 — Use OEM specification
• Tie rod end nut × 1 — Use OEM specification
• Brake rotor mounting screws (if applicable) × 2 — Use OEM specification
• Thread locker (medium strength) × 1 — Loctite 243 or equivalent

Preparation

1. Park vehicle on level surface and chock rear wheels securely
2. Loosen wheel lug nuts while vehicle is on ground (do not remove)
3. Raise front of vehicle and support on jack stands at manufacturer-specified jacking points
4. Remove front wheel on side being serviced
5. Spray all suspension fasteners with penetrant and allow to soak for 15-20 minutes
6. Place a floor jack under lower control arm to support suspension load

Procedure

1. 1

   Remove brake caliper and rotor
   Remove the two brake caliper mounting bolts from the back of the caliper bracket. Carefully slide the caliper and bracket assembly off the rotor. DO NOT let the caliper hang by the brake hose - support it using a caliper hanger or secure it to the suspension with wire. Remove the rotor retaining screw (if present) and slide the brake rotor off the hub.
2. 2

   Disconnect ABS wheel speed sensor
   Locate the ABS wheel speed sensor connector near the strut tower or wheel well. Disconnect the electrical connector by pressing the release tab. Remove the sensor mounting bolt (typically 6mm Allen or 8mm hex) and carefully extract the sensor from the knuckle. Set aside to prevent damage.
3. 3

   Disconnect tie rod end from knuckle
   Remove the castle nut securing the tie rod end to the steering knuckle. Use a tie rod end separator tool to break the taper connection. Do not use excessive force with a pickle fork as this may damage the boot. If reusing the tie rod end, use a proper separation tool to avoid damage. Count and record the number of turns when removing the tie rod end from the tie rod for approximate alignment reference.
4. 4

   Disconnect sway bar end link
   Locate the sway bar end link connection at the lower control arm or strut. Hold the shaft with an Allen key to prevent spinning, then remove the upper or lower nut (depending on which end connects to the knuckle assembly). Separate the end link from its mounting point.
   Torque spec

   Sway Bar Link Nuts55 Nm (41 lb-ft)
5. 5

   Remove strut-to-knuckle mounting bolts
   Locate the two large bolts connecting the strut assembly to the steering knuckle (typically at the top of the knuckle). These are often pinch-type bolts that clamp the knuckle to the strut. Support the knuckle with one hand or a secondary jack, then remove both strut mounting bolts. The knuckle will now be free at the top.
   ⚠The knuckle will become loose once these bolts are removed. Ensure it is properly supported to prevent it from falling and causing injury or damage.
   Torque spec

   Strut Bolts156 Nm (115 lb-ft)
6. 6

   Disconnect lower ball joint from control arm
   Locate the ball joint nut connecting the lower ball joint (on the bottom of the knuckle) to the lower control arm. Remove the ball joint nut. Use a ball joint separator tool or pickle fork to break the taper connection between the ball joint stud and the control arm. Apply steady pressure with the separator while tapping with a hammer if necessary.
   ⚠Ball joint taper connections are very tight. Use proper separation tools to avoid damaging the control arm threads or ball joint boot.
   Torque spec

   Ball Joint Nut119 Nm (88 lb-ft)
7. 7

   Remove knuckle assembly from vehicle
   With all connections separated, carefully maneuver the steering knuckle assembly away from the vehicle. You may need to rotate the assembly and work it past the CV axle shaft and brake dust shield. If the hub/bearing is pressed into the knuckle and staying with the axle, you may need to use a hub puller to separate them. Set the old knuckle aside on a clean work surface.
8. 8

   Transfer or install wheel bearing/hub assembly
   If the wheel bearing and hub are being reused, carefully press or drive them out of the old knuckle and into the new knuckle using appropriate press tools and bearing drivers. Ensure the bearing is seated fully and squarely in the bore. If installing a new hub/bearing assembly, follow manufacturer pressing specifications. Clean all mating surfaces with brake cleaner before assembly.
   ⚠Wheel bearing installation requires precise alignment and even pressure. Cocked or improperly seated bearings will fail prematurely. Consider professional press work if tools are not available.
9. 9

   Install knuckle assembly to vehicle
   Position the new knuckle assembly into place, sliding it over the CV axle shaft and aligning with the lower control arm ball joint and strut mounting points. Insert the ball joint stud into the lower control arm and thread on the new ball joint nut hand-tight. Align the knuckle with the strut and insert both strut mounting bolts hand-tight.
10. 10

    Torque strut and ball joint connections
    Using a torque wrench, tighten the two strut-to-knuckle mounting bolts to specification. Then torque the lower ball joint nut to specification. Ensure all fasteners are clean and threads are not damaged before torquing.
    Torque spec

    Strut Bolts156 Nm (115 lb-ft)

    Ball Joint Nut119 Nm (88 lb-ft)
11. 11

    Reconnect tie rod end and sway bar link
    Thread the tie rod end back onto the tie rod approximately the same number of turns as recorded during removal. Insert the tie rod end taper into the knuckle and install the castle nut, torquing to specification. Install cotter pin if equipped. Reconnect the sway bar end link, holding the shaft with an Allen key while torquing the nut to specification.
    Torque spec

    Sway Bar Link Nuts55 Nm (41 lb-ft)
12. 12

    Reinstall ABS sensor and brake components
    Clean the ABS sensor bore in the knuckle with brake cleaner. Apply a thin coat of anti-seize to the sensor body (not the tip) and insert into the knuckle. Torque the sensor mounting bolt to specification. Reconnect the electrical connector. Slide the brake rotor onto the hub and install retaining screw if present. Mount the brake caliper and bracket assembly over the rotor and torque the caliper mounting bolts to specification.
    Torque spec

    Mounting Bolts37 Nm (27 lb-ft)
13. 13

    Reinstall wheel and lower vehicle
    Install the wheel and thread all lug nuts hand-tight. Lower the vehicle until the tire just contacts the ground but the suspension is not fully loaded. Torque the wheel lug nuts in a star pattern to specification. Fully lower the vehicle and remove jack stands.
    Torque spec

    Wheel Lug Nuts183 Nm (135 lb-ft)

Reassembly

1. Control arm bolts (if loosened) must be torqued to specification with vehicle weight on wheels - drive vehicle forward and backward several feet, then torque while on level ground
2. Verify all electrical connectors are fully seated and secured, especially ABS sensor
3. Check brake pedal feel before moving vehicle - pump brake pedal several times to ensure proper caliper piston position
4. Inspect for any fluid leaks around brake connections

Verification

• Verify all torque specifications have been met using a calibrated torque wrench
• Rotate the wheel hub by hand to ensure smooth rotation with no binding or grinding
• Check that ABS warning light extinguishes after starting vehicle and driving briefly
• Test brake function in a safe area at low speed before normal operation
• Schedule four-wheel alignment immediately - suspension geometry has been altered and vehicle will likely pull or have uneven tire wear without alignment
• After first 50-100 miles, re-torque all critical fasteners (strut bolts, ball joint nut, wheel lug nuts) to specification

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