Control Arm Bushing - Front Upper

Replace the front upper control arm bushings on a 2019 Mercedes-Benz G-Class 4.0L Turbo V8, requiring control arm removal and bushing press-out/press-in operations.

Warnings

Tools required

Parts

• Front upper control arm bushing kit × 2 — Use OEM specification
• Ball joint cotter pin (if applicable) × 1 — 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 vehicle on lift or jack stands to working height
4. Remove front wheel on side being serviced
5. Spray all suspension fasteners with penetrating oil and allow to soak for 10-15 minutes

Procedure

1. 1

   Support Lower Control Arm
   Position a jack stand or hydraulic jack under the lower control arm near the ball joint to support the weight of the suspension components. This prevents the suspension from dropping when the upper control arm is disconnected and maintains safe working clearance.
2. 2

   Disconnect Upper Ball Joint from Knuckle
   Remove the self-locking ball joint nut from the upper ball joint stud using the appropriate socket (verify size against Mercedes WIS). Note: modern Mercedes suspensions typically do not use a cotter pin/castle nut in this location. Use a ball joint separator tool to break the taper between the ball joint stud and steering knuckle. Apply upward pressure with the separator while tapping the knuckle boss with a hammer to release the joint. Do not strike the ball joint stud directly.
3. 3

   Remove Front Control Arm Frame Mounting Bolts
   Locate the two control arm mounting bolts that secure the front of the upper control arm to the frame rail. Remove both bolts completely and note the position and orientation of any washers, spacers, or hardware for reassembly reference. Remove both bolts completely and note the position and orientation of any washers, spacers, or brackets for reassembly reference. The control arm may now pivot downward.
4. 4

   Remove Rear Control Arm Frame Mounting Bolt
   Locate the rear control arm mounting bolt that secures the rear bushing to the frame bracket. Remove this bolt completely. With all mounting points disconnected, carefully lower and remove the upper control arm from the vehicle. Note the orientation of the control arm for correct reinstallation.
5. 5

   Inspect Control Arm and Bushing Condition
   With the control arm removed, inspect the bushing bores for damage, cracking, or deformation. Check the ball joint for excessive play or torn boots. Clean the control arm thoroughly with a wire brush, removing all dirt and corrosion from the bushing mounting areas. Examine both front and rear bushing locations to determine which require replacement.
6. 6

   Press Out Old Bushings
   Secure the control arm/link in a hydraulic press or bushing press tool per Mercedes WIS. Select the appropriate press adapters to contact only the outer bushing shell, not the arm. Verify the correct bushing removal method for this specific W463 component before proceeding. Apply steady pressure to press the old bushing out of the control arm bore. Repeat for both front and rear bushings. If bushings are bonded rubber type, they may require cutting or splitting before pressing. Clean the bushing bore thoroughly after removal.
7. 7

   Press In New Bushings
   Apply a light coating of soapy water or approved bushing lubricant to the outer shell of the new bushing and the control arm bore (do not use petroleum-based products). Align the new bushing with the bore, ensuring any orientation marks or voids are positioned correctly per OEM specifications. Using the hydraulic press with proper adapters, press the bushing straight into the bore until fully seated and flush with the control arm. The bushing must be pressed evenly to avoid cocking or damage. Repeat for both bushings.
8. 8

   Install Control Arm to Frame
   Position the control arm back into its mounting location on the frame. Install the rear mounting bolt first, threading it through the frame bracket and rear bushing, but do not tighten. Install the two front mounting bolts with their eccentric washers or shims in the same orientation as removed. Thread all bolts finger-tight to maintain position but allow articulation for ball joint connection.
9. 9

   Connect Ball Joint to Knuckle
   Use the jack under the lower control arm to raise the suspension slightly, bringing the steering knuckle into alignment with the upper ball joint stud. Insert the ball joint stud into the knuckle taper. Install a new self-locking ball joint nut and torque to specification (verify value against Mercedes WIS). This platform does not use a castle nut/cotter pin at this location.
   Torque spec

   Upper Ball Joint Nut101 Nm (75 lb-ft)
10. 10

    Install Wheel and Lower Vehicle
    Install the wheel onto the hub and thread lug nuts by hand to prevent cross-threading. Tighten lug nuts in a star pattern snug but not to final torque. Lower the vehicle until the tires just contact the ground but the suspension is still supporting some vehicle weight. This establishes normal ride height for final bushing torque.
11. 11

    Torque Control Arm Bolts at Ride Height
    With the vehicle weight on the suspension at normal ride height, torque the front control arm mounting bolts and the rear control arm mounting bolt to the manufacturer-specified values (verify each against Mercedes WIS; note that these fasteners may require a torque-plus-angle specification and new bolts). This critical step ensures bushings are torqued in their neutral position, preventing premature wear or binding. Do not torque these fasteners with the suspension hanging or compressed.
    Torque spec

    Control Arm Bolts195 Nm (144 lb-ft)
12. 12

    Final Torque Wheel Lug Nuts
    Fully lower the vehicle to the ground. Using a torque wrench, tighten the wheel lug nuts to specification in a star pattern to ensure even clamping force on the wheel.
    Torque spec

    Wheel Lug Nuts142.4 Nm (105 lb-ft)

Reassembly

1. Reassembly is covered in the procedure steps above
2. Ensure all fasteners are torqued to specification at the correct suspension position
3. Verify ball joint cotter pin is properly installed and bent to prevent loosening

Verification

• Test drive vehicle at low speed and verify no abnormal noises or steering binding
• Check that steering returns to center properly after turns
• Verify no clunking or play in front suspension over bumps
• Schedule wheel alignment as suspension geometry has been altered
• After 50-100 miles, re-check torque on control arm mounting bolts

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