Ball Joint - Upper

Replace the upper ball joint on a 2007-2013 Mercedes-Benz S65 AMG, requiring removal of the upper control arm and separation of the ball joint from the steering knuckle.

Warnings

Tools required

Parts

• Upper ball joint × 1 — Use OEM specification
• Cotter pin × 1 — New cotter pin required
• Pinch bolt × 1 — New bolt required per torque spec

Preparation

1. Park vehicle on level surface and engage parking brake
2. Loosen wheel lug nuts while vehicle is on ground
3. Raise front of vehicle and support securely on jack stands at manufacturer lift points
4. Remove front wheel on side being serviced
5. Spray all fasteners with penetrating oil and allow to soak for 15-20 minutes

Procedure

1. 1

   Remove cotter pin and loosen ball joint nut
   Locate the upper ball joint where it connects to the steering knuckle. Straighten and remove the cotter pin using pliers or a punch. Use a 21mm socket to loosen (but do not remove) the ball joint nut several turns. Leave the nut on the threads to prevent sudden separation.
2. 2

   Separate ball joint from knuckle
   Position a ball joint separator or pickle fork between the upper control arm and the steering knuckle at the ball joint taper. Strike the separator firmly with a hammer or use a ball joint separator tool to break the taper free. Once separated, remove the ball joint nut completely and lift the control arm away from the knuckle.
   ⚠The ball joint may separate suddenly. Ensure the nut is still threaded on to control separation.
3. 3

   Disconnect sway bar link if necessary
   If access is restricted, disconnect the sway bar link from the upper control arm. Hold the shaft with an Allen key while loosening the nut with an 18mm wrench to prevent the link from spinning.
   Torque spec

   Sway Bar Link Nuts55 Nm (41 lb-ft)
4. 4

   Remove strut tower nuts
   Open the hood and locate the strut tower nuts at the top of the strut assembly. Remove the three nuts securing the upper control arm/strut assembly to the strut tower using a 19mm socket. Support the control arm as you remove the final nut.
   ⚠Support the control arm to prevent it from dropping when the final nut is removed.
   Torque spec

   Strut Tower Nuts50 Nm (37 lb-ft)
5. 5

   Remove control arm mounting bolts
   Locate the control arm mounting bolts that secure the upper control arm to the chassis. These are typically at the rear of the control arm. Remove both bolts using appropriate sockets and a breaker bar if necessary. Note the position and orientation of any washers or bushings.
   Torque spec

   Control Arm Bolts165 Nm (122 lb-ft)
6. 6

   Remove upper control arm assembly
   Carefully lower and remove the upper control arm assembly from the vehicle. Work it free from the mounting points, taking care not to damage brake lines, ABS sensors, or other components. Place the control arm on a clean workbench.
7. 7

   Press out old ball joint
   Secure the control arm in a vise or position it in a ball joint press. Using the appropriate adapters, press the old ball joint out of the control arm. Apply steady, even pressure. Clean the ball joint bore in the control arm thoroughly with a wire brush, removing all dirt, rust, and debris.
8. 8

   Press in new ball joint
   Position the new ball joint in the control arm bore, ensuring it is properly aligned. Using the ball joint press with the correct adapters, press the new ball joint into the control arm until it is fully seated. The ball joint should be flush with the control arm surface or seated to the depth specified by the manufacturer.
   ⚠Ensure the ball joint is pressed in straight to avoid damaging the control arm bore or the new ball joint.
9. 9

   Reinstall upper control arm
   Position the upper control arm back into the vehicle. Install the control arm mounting bolts through the chassis brackets, but do not fully tighten yet. Thread the bolts by hand to ensure proper alignment.
10. 10

    Install strut tower nuts
    Align the strut tower studs with the holes in the strut tower and install the three nuts. Tighten the strut tower nuts to specification using a torque wrench.
    Torque spec

    Strut Tower Nuts50 Nm (37 lb-ft)
11. 11

    Connect ball joint to knuckle
    Lift the upper control arm and insert the ball joint stud into the steering knuckle. Install the NEW ball joint nut and tighten to specification. If using the lower specification (119 Nm), install without cotter pin. If using the higher specification (137 Nm), ensure the castellations align with the cotter pin hole, then install a new cotter pin and bend the ends to secure.
    Torque spec

    Ball Joint Nut119 Nm (88 lb-ft)
12. 12

    Reconnect sway bar link
    If previously disconnected, reconnect the sway bar link to the upper control arm. Hold the shaft with an Allen key and tighten the nut to specification.
    Torque spec

    Sway Bar Link Nuts55 Nm (41 lb-ft)
13. 13

    Install wheel and lower vehicle
    Reinstall the wheel and thread the lug nuts by hand. Lower the vehicle until the tire just contacts the ground but the suspension is not fully compressed. This puts vehicle weight on the wheels.
14. 14

    Torque control arm bolts and wheel lug nuts
    With the vehicle weight on the wheels (but still supported by jack), torque the control arm mounting bolts to specification. This ensures proper bushing alignment. Then torque the wheel lug nuts in a star pattern to specification. Fully lower the vehicle and remove jack stands.
    Torque spec

    Control Arm Bolts165 Nm (122 lb-ft)

    Wheel Lug Nuts183 Nm (135 lb-ft)

Reassembly

1. Ensure all fasteners are torqued to specification
2. Verify the new cotter pin is properly installed and bent to prevent loosening
3. Double-check that control arm bolts were torqued with vehicle weight on wheels

Verification

• Start the engine and turn the steering wheel lock-to-lock while stationary to check for any binding or unusual noises
• Test drive the vehicle at low speed and verify normal steering operation and no clunking noises over bumps
• Perform a visual inspection of the ball joint and all connections to ensure everything is properly seated
• Schedule a professional wheel alignment as suspension geometry has been altered

More procedures for this vehicle