Subframe Bushing

This procedure covers the removal and replacement of subframe bushings on a 2019 Mercedes-Benz G-Class with 4.0L Turbo V8 engine, requiring subframe lowering or partial removal to access bushing mounting points.

Warnings

Tools required

Parts

• Front subframe bushing set (4 bushings) × 1 — A4633240200 or equivalent
• Subframe mounting bolts (if corroded) × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery terminal to prevent electrical issues during work
3. Raise front of vehicle and support securely on jack stands at manufacturer-specified lift points
4. Remove front wheels using 22mm socket
5. Apply penetrating oil to all subframe mounting bolts and allow to soak for 15-20 minutes
6. Photograph or mark subframe position relative to body for alignment reference during reinstallation

Procedure

1. 1

   Remove Front Skid Plate and Undercarriage Panels
   Locate and remove the front skid plate protecting the engine and subframe area. Remove fasteners securing undercarriage panels for access to subframe mounting points. Fasteners are typically Torx or E-Torx. Inspect and set aside panels in organized manner for reinstallation.
2. 2

   Disconnect Steering Components
   Locate the steering rack connection points to the subframe. Mark the steering coupling position before removal. Remove the steering coupling pinch bolt (typically E-Torx) securing the steering shaft to the rack. Separate the coupling by spreading the clamp slightly with a flathead screwdriver while pulling the shaft away from the rack. Support the steering shaft to prevent strain on the column.
3. 3

   Disconnect Front Sway Bar Links
   Locate the front sway bar end links connecting the sway bar to the suspension (lower control arms on IFS chassis, or to the live axle/trailing arms on solid-axle chassis — verify per this vehicle's front suspension type). Remove the upper mounting nuts securing each end link using appropriate socket (typically 16mm or 18mm). Hold the ball stud with an Allen key or Torx bit to prevent spinning if necessary. Allow sway bar to hang freely or secure with wire to prevent interference.
4. 4

   Support Engine and Transmission
   Note: the 2019 G-Class uses a body-on-frame ladder chassis; the engine/transmission mount to the frame, not a removable subframe. Verify the actual mounting architecture before supporting components. If engine support is required, position a floor jack with wood block under a structural point on the engine oil pan (toward the rear of the pan to avoid drain plug), not directly on thin pan sheet metal. Raise jack until it just contacts the pan without lifting. This prevents engine from dropping when subframe is lowered. Verify transmission is also supported by the same jack or position a second jack under the transmission.
5. 5

   Position Subframe Support
   Position a transmission jack or subframe support fixture under the center of the front subframe. Raise the support until it contacts the subframe firmly but does not bear significant weight yet. Secure any safety straps or chains if using a transmission jack to prevent subframe from shifting during removal.
6. 6

   Remove Subframe Mounting Bolts
   Locate the main subframe mounting bolts (typically 4 primary bolts, 2 per side, plus possible additional stabilizer bolts). Begin with rear bolts first. Use breaker bar to loosen each bolt several turns but do not remove completely. Move to front bolts and loosen similarly. Once all bolts are loose, verify subframe is securely supported on the jack. Remove all bolts completely, keeping track of any washers or spacers. Lower the subframe slowly and evenly using the support jack, lowering approximately 4-6 inches to access bushing mounting areas.
7. 7

   Access and Inspect Bushings
   With subframe lowered, inspect the bushing mounting points at each corner of the subframe where it connects to the body. Bushings are typically press-fit into the subframe brackets or body mounting points. Assess the condition and note whether bushings are located in the subframe itself or in the body-side brackets. Check for corrosion, torn rubber, or separation of the bushing from its metal sleeve.
8. 8

   Remove Old Bushings
   Remove the old bushings from their mounting locations. If bushings are pressed into subframe brackets, use a hydraulic press with appropriate adapters or a bushing removal tool set to press out the old bushings. Alternatively, use a large C-clamp or ball joint press to drive out bushings. For body-side bushings, access may require removing the bracket from the body first (check for Torx or E-Torx bolts securing the bracket). Clean all mounting surfaces thoroughly with wire brush, removing rust, old rubber, and debris.
9. 9

   Install New Bushings
   Verify new bushings match the orientation and design of the originals. Note any directional markings or voids in the bushing that must align with load paths. Apply light coating of soapy water or bushing lubricant to the outer sleeve to ease installation (do not use petroleum-based lubricants). Using a hydraulic press or bushing installation tool, press new bushings into their mounting locations, ensuring they seat fully and squarely. The bushing should be flush or at the specified depth in the bracket. Repeat for all four subframe bushings.
10. 10

    Raise and Align Subframe
    With new bushings installed, use the support jack to raise the subframe back into position. Align the subframe mounting holes with the body mounting points, referencing the alignment marks made during disassembly. The subframe must align precisely for proper suspension geometry. Use pry bars or alignment pins if necessary to shift the subframe into exact position. Do not force bolts through misaligned holes.
11. 11

    Install Subframe Mounting Bolts
    Install all subframe mounting bolts with any original washers or spacers in their correct positions. Start all bolts by hand to ensure threads engage properly. Tighten bolts in a cross pattern (rear left, front right, rear right, front left) to draw the subframe up evenly. Torque bolts to manufacturer specification following the specified sequence. If torque-plus-angle bolts are used, first torque to initial specification, then apply the additional rotation angle as specified in service documentation. Torque specification is unknown for this platform and could be significantly higher than typical suspension bolts, often with a torque-plus-angle stage. Do not estimate — obtain the exact spec from Mercedes-Benz WIS before installation.
    ⚠Subframe bolt torque specification for this platform is not available in the provided torque database. Consult Mercedes-Benz service manual for exact torque and angle specifications, as these are critical for structural integrity.
12. 12

    Reconnect Steering Components
    Align the steering coupling with the steering rack input shaft, matching the marks made during disassembly. Slide the coupling onto the shaft and install the pinch bolt. Torque the pinch bolt to Mercedes-Benz specification (value unconfirmed for this platform — verify in WIS; note Mercedes steering coupling bolts are frequently single-use torque-to-yield and may require replacement). Ensure steering moves freely through full range of motion without binding.
13. 13

    Reconnect Sway Bar Links
    Reconnect the front sway bar end links to the lower control arms. Install the upper mounting nuts and tighten while holding the ball stud to prevent spinning. Torque nuts to Mercedes-Benz specification (value unconfirmed for this platform — verify in WIS before final tightening).
14. 14

    Reinstall Undercarriage Panels
    Reinstall all undercarriage panels and the front skid plate in reverse order of removal. Ensure all Torx and E-Torx fasteners are properly seated and tightened. Verify no tools or parts have been left in the undercarriage area.
15. 15

    Reinstall Wheels and Lower Vehicle
    Reinstall front wheels, hand-tightening lug nuts in a star pattern. Lower vehicle to the ground and torque lug nuts to specification in a star pattern.
    Torque spec

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

Reassembly

1. Reconnect negative battery terminal and verify no electrical faults
2. Remove jack stands and lower vehicle completely to the ground
3. Perform final torque verification on all critical fasteners after vehicle weight settles
4. Test drive vehicle in safe area to verify proper handling and absence of noise or vibration

Verification

• Start engine and verify no unusual noises from front suspension or subframe area
• Turn steering wheel lock-to-lock while stationary to verify steering operates smoothly without binding
• Perform test drive at low speeds, checking for clunking, rattling, or abnormal handling
• Inspect subframe mounting points for any gaps or misalignment after test drive
• Verify steering wheel is centered when driving straight and vehicle tracks properly
• Re-check all subframe mounting bolt torque after 50-100 miles of driving as bushings seat

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