Upper Control Arm - Front

Replace the front upper control arm on a 2007-2013 Mercedes-Benz S65 AMG, disconnecting the ball joint and mounting bolts, then installing a new control arm with proper torque specifications.

Warnings

Tools required

Parts

• Front upper control arm assembly × 1 — Use OEM specification
• Ball joint nut (if damaged) × 1 — A2219970745
• Control arm mounting bolts (if corroded) × 2 — Use OEM specification

Preparation

1. Park vehicle on level surface and engage parking brake
2. Loosen front 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 control arm mounting bolts and ball joint nut with penetrating oil and allow to soak

Procedure

1. 1

   Remove ball joint nut
   Locate the upper control arm ball joint where it connects to the steering knuckle. Using an 18mm socket, remove the ball joint castle nut completely. Note the condition of the nut for potential replacement.
2. 2

   Separate ball joint from knuckle
   Using a ball joint separator tool or pickle fork, carefully separate the upper control arm ball joint taper from the steering knuckle. Apply force gradually to avoid damaging the knuckle threads or ball joint boot. Once separated, support the knuckle to prevent stress on the lower control arm and brake components.
   ⚠Do not strike the steering knuckle with a hammer as this may damage the bearing assembly.
3. 3

   Support suspension assembly
   Place a floor jack under the lower control arm or suspension subframe to support the weight of the suspension components. This prevents the assembly from dropping when the upper control arm is removed.
4. 4

   Remove control arm rear mounting bolt
   Locate the rear control arm mounting bolt at the chassis. Using a 16mm socket and breaker bar, remove the bolt completely. Note that this bolt passes through a bushing and may require prying the control arm slightly to extract the bolt. Keep the bolt for inspection.
5. 5

   Remove control arm front mounting bolt
   Using a 16mm socket, remove the front control arm mounting bolt from the chassis bracket. The control arm should now be free from the vehicle. Remove the control arm carefully, noting its orientation for proper installation of the replacement.
6. 6

   Clean mounting surfaces
   Use a wire brush to clean the control arm mounting bolt holes in the chassis and the ball joint taper seat in the steering knuckle. Remove any corrosion, dirt, or old thread locking compound. Inspect mounting points for damage or excessive wear.
7. 7

   Install new control arm
   Position the new upper control arm into place, aligning the ball joint with the steering knuckle taper. Insert the front and rear mounting bolts through the chassis brackets and control arm bushings, but do not tighten yet. Thread bolts by hand to ensure proper alignment.
   ℹ️Ensure the control arm is correctly oriented with the ball joint pointing downward toward the knuckle.
8. 8

   Install ball joint nut
   Thread the castle nut onto the ball joint stud and tighten it to pull the taper fully seated into the steering knuckle. Torque the ball joint nut to specification using a torque wrench.
   Torque spec

   Ball Joint Nut119 Nm (88 lb-ft)
9. 9

   Snug control arm mounting bolts
   Using a 16mm socket, snug the front and rear control arm mounting bolts finger-tight plus an additional 1/4 turn. Do not torque to final specification at this time. The bolts must be torqued with vehicle weight on the suspension.
10. 10

    Reinstall wheel and lower vehicle
    Install the wheel and thread the lug nuts by hand. Lower the vehicle until the tire just touches the ground but the jack stands still support most of the weight. Torque the wheel lug nuts to specification in a star pattern. Remove jack stands and lower vehicle completely to the ground.
    Torque spec

    Wheel Lug Nuts183 Nm (135 lb-ft)
11. 11

    Torque control arm bolts with weight on wheels
    With the vehicle fully lowered and weight on the wheels, bounce the front suspension several times to settle the bushings into their natural position. Using a torque wrench and 16mm socket, torque both the front and rear control arm mounting bolts to specification. This ensures the bushings are not pre-loaded in a twisted position.
    ⚠Torquing control arm bolts with suspension hanging will cause premature bushing failure. Always torque with vehicle at ride height.
    Torque spec

    Control Arm Bolts165 Nm (122 lb-ft)

Reassembly

1. Repeat procedure for opposite side if necessary
2. Verify all fasteners are torqued to specification
3. Check that ball joint nut cotter pin hole aligns (if equipped with castle nut and pin design)

Verification

• Test drive vehicle at low speed and verify no clunking or abnormal noises from front suspension
• Check steering feel and verify no pulling or wandering
• Schedule four-wheel alignment immediately - control arm replacement significantly affects camber and caster angles
• After 50-100 miles, re-check control arm bolt torque with vehicle at ride height

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