Trailing Arm

This procedure covers the removal and replacement of the rear trailing arm (also known as the lower control arm) on the 2007-2013 Mercedes-Benz S65 AMG with the M275 6.0L V12 BiTurbo engine.

Warnings

Tools required

Parts

• Rear trailing arm assembly × 1 — Use OEM specification
• Self-locking nuts (if applicable) × 2 — Use OEM specification
• Trailing arm bushings (if replacing separately) × 2 — Use OEM specification

Preparation

1. Park vehicle on level, solid surface and engage parking brake
2. If equipped with Airmatic suspension, use STAR diagnostic tool to disable suspension control module to prevent automatic leveling during service
3. Loosen rear wheel lug nuts while vehicle is on ground
4. Raise rear of vehicle and support on manufacturer-specified jack stand points on chassis rails
5. Remove rear wheel on side being serviced
6. Spray all trailing arm bolts, ball joint connections, and mounting points with penetrating oil

Procedure

1. 1

   Support the rear suspension assembly
   Position a floor jack under the rear hub assembly or trailing arm itself to support the weight of the suspension components. Raise jack just enough to contact but not lift the suspension. This prevents the assembly from dropping when fasteners are removed.
2. 2

   Disconnect the ball joint (if equipped)
   If the trailing arm connects to other suspension components via a ball joint, remove the ball joint nut using a 16mm socket. Use a ball joint separator tool to press the ball joint taper out of the mounting hole. Do not use a pickle fork if reusing the ball joint boot. If no ball joint is present, proceed to next step.
   Torque spec

   Ball Joint Nut119 Nm (88 lb-ft)
3. 3

   Disconnect sway bar link if necessary
   If the sway bar link attaches to the trailing arm and interferes with removal, hold the link shaft with an Allen key and remove the nut using appropriate socket. Swing the link away from the work area.
   Torque spec

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

   Remove front trailing arm mounting bolt
   Locate the front mounting bolt that attaches the trailing arm to the subframe or chassis. This is typically the forward-most attachment point. Use an 18mm socket and breaker bar to remove the bolt completely. Note the orientation of any washers or spacers. The trailing arm will now pivot on the rear mount only.
5. 5

   Remove rear trailing arm mounting bolt
   Remove the rear mounting bolt that secures the trailing arm to the rear subframe or differential carrier mounting. Use an 18mm socket and breaker bar. Once this bolt is removed, carefully lower the floor jack to control the descent of the trailing arm assembly. The arm should now be free from the vehicle.
   ⚠Control the floor jack carefully as the trailing arm may drop suddenly when the last bolt is removed.
6. 6

   Inspect mounting points and bushings
   With the trailing arm removed, inspect both vehicle mounting points for damage, corrosion, or wallowed-out holes. Check the bushings in the trailing arm for cracks, separation, or deterioration. Clean all mounting surfaces with a wire brush. If bushings need pressing out, special tools or a hydraulic press may be required.
7. 7

   Install new trailing arm into position
   Position the new or refurbished trailing arm into the mounting location. Support it with the floor jack at the hub end. Align the rear mounting hole first and insert the rear bolt finger-tight. Do not fully torque at this stage.
8. 8

   Install front mounting bolt
   Align the front mounting hole of the trailing arm with the chassis or subframe mounting point. You may need to use a pry bar or adjust the floor jack height to align holes perfectly. Insert the front mounting bolt and thread finger-tight. Ensure any washers or spacers are in correct orientation.
9. 9

   Reconnect ball joint and sway bar link
   If a ball joint connection was removed, seat the ball joint taper into the mounting hole and install the nut. If the sway bar link was disconnected, reconnect it to the trailing arm, holding the shaft with an Allen key while tightening the nut.
   Torque spec

   Ball Joint Nut119 Nm (88 lb-ft)

   Sway Bar Link Nuts55 Nm (41 lb-ft)
10. 10

    Preliminary tightening of control arm bolts
    With the suspension still supported by the floor jack and the vehicle on jack stands, snug the front and rear trailing arm mounting bolts but do NOT torque to final specification yet. These must be torqued with vehicle weight on wheels.
11. 11

    Reinstall wheel and lower vehicle
    Reinstall the rear wheel and thread lug nuts by hand. Lower the vehicle from jack stands until full vehicle weight is on all four wheels. The suspension must be at normal ride height for final torquing of control arm bolts.
    Torque spec

    Wheel Lug Nuts183 Nm (135 lb-ft)
12. 12

    Final torque control arm bolts
    With vehicle weight on wheels, crawl under the vehicle and torque both the front and rear trailing arm mounting bolts to specification using a torque wrench. This ensures bushings are torqued in their normal operating position and prevents premature bushing failure.
    ⚠Control arm bolts MUST be torqued with vehicle weight on wheels. Failure to do so will cause premature bushing failure and alignment issues.
    Torque spec

    Control Arm Bolts165 Nm (122 lb-ft)

Reassembly

1. If Airmatic suspension was disabled, reconnect diagnostic tool and re-enable suspension control module
2. Perform a final torque check on all fasteners after test drive
3. Road test vehicle to verify no abnormal noises or handling issues

Verification

• Verify all mounting bolts are torqued to specification with vehicle weight on wheels
• Bounce the rear of the vehicle to ensure suspension moves freely without binding or noise
• Schedule a four-wheel alignment, as trailing arm replacement will affect rear camber, toe, and thrust angle settings
• Test drive the vehicle and verify stable handling, no pulling, and no clunking or knocking noises from rear suspension

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