Trailing Arm

This procedure covers the removal and replacement of the rear trailing arm (also called control arm or radius arm) on a 4WD 2007 Ram 3500 with the 5.9L Cummins diesel engine.

Warnings

Tools required

Parts

• Trailing arm (rear control arm) × 1 — Use OEM specification or heavy-duty aftermarket
• Trailing arm bushing set × 1 — Often included with arm or separate
• Trailing arm mounting bolts and hardware × 1 — Use OEM hardware

Preparation

1. Park vehicle on level, solid ground and engage parking brake
2. Place wheel chocks in front of front wheels
3. Loosen (but do not remove) the lug nuts on the rear wheel on the side being serviced
4. Apply penetrating oil to all trailing arm bolts and allow to soak for at least 30 minutes (preferably 24 hours)
5. Raise the rear of the vehicle using a floor jack at the frame rail
6. Support the frame with heavy-duty jack stands on both sides at appropriate jacking points
7. Remove the rear wheel on the side being serviced
8. Position a transmission jack or sturdy adjustable jack stand under the rear axle to support its weight independently

Procedure

1. 1

   Inspect and document trailing arm condition
   Before removal, inspect the trailing arm for cracks, bending, or other damage. Check bushings for deterioration, cracking, or separation. Take photos if needed for reference during reassembly. Note the orientation of any washers, spacers, or shims at mounting points.
2. 2

   Support the rear axle
   Using a transmission jack or heavy-duty adjustable jack stand, support the rear axle tube directly under the axle housing near the trailing arm mounting point. Raise slightly to take the load off the trailing arm but do not lift the vehicle. The axle should be at approximately ride height position.
3. 3

   Remove frame-side trailing arm bolt
   Locate the forward trailing arm mounting bolt at the frame bracket. This is a large-diameter bolt; verify the exact nut and bolt head sizes against the factory service manual before selecting a socket. Using a breaker bar and socket, remove the nut from the frame-side bolt. If the bolt spins, use a wrench on the bolt head to hold it. Tap the bolt out using a hammer and punch if necessary. The bolt may be very tight due to corrosion.
4. 4

   Remove axle-side trailing arm bolt
   Locate the rear trailing arm mounting bolt at the axle bracket. This bolt connects the trailing arm to the axle housing. Remove the nut and extract the bolt. You may need to use a pry bar to create clearance or tap the bolt through with a hammer. Support the trailing arm as the bolt is removed to prevent it from dropping suddenly.
5. 5

   Remove trailing arm from vehicle
   With both bolts removed, carefully lower and remove the trailing arm from the vehicle. The arm may be heavy and awkward to maneuver. Inspect the mounting brackets on both the frame and axle for damage, cracks, or excessive wear. Clean the mounting surfaces with a wire brush.
6. 6

   Prepare new trailing arm
   Compare the new trailing arm to the old unit to verify correct part. Check that bushings are properly installed and oriented if they came separately. Some arms require bushing installation prior to mounting. Apply a thin coat of anti-seize compound to the bolt sleeves inside the bushings.
7. 7

   Install trailing arm to axle bracket
   Lift the new trailing arm into position and align the rear bushing with the axle bracket. Insert the axle-side bolt through the bracket and bushing. Start the nut on the bolt but do not tighten yet. The bolt should pass through freely; if not, check alignment and bushing position.
8. 8

   Install trailing arm to frame bracket
   Align the forward end of the trailing arm with the frame bracket. You may need to use the jack under the axle to adjust ride height for proper alignment. Insert the frame-side bolt through the bracket and bushing. Start the nut on the bolt but do not tighten. Ensure all washers and spacers are in their original positions.
9. 9

   Adjust axle position and load suspension
   Using the jack under the axle, raise the axle to simulate normal ride height. The suspension should be at approximately the same position as when the vehicle is on the ground. This is critical for proper bushing alignment and longevity. The trailing arm should be roughly parallel to the ground or at slight angle depending on factory specifications.
10. 10

    Torque trailing arm bolts
    With the suspension loaded to ride height, torque both trailing arm bolts to manufacturer specifications. While exact torque values are not provided in the database, this application requires a high torque value; consult a factory service manual for the exact specification and use a torque wrench rated to reach it. Consult a factory service manual for exact values. Torque the frame-side bolt first, then the axle-side bolt. Do not torque with suspension unloaded or bushings will bind prematurely.

Reassembly

1. Remove the jack or jack stand from under the axle
2. Reinstall the rear wheel and hand-tighten lug nuts in a star pattern
3. Carefully lower the vehicle to the ground
4. Torque wheel lug nuts to 135 ft-lbs in a star pattern with the vehicle on the ground
5. If replacing trailing arms on both sides, repeat the procedure for the opposite side

Verification

• Perform a visual inspection to ensure all bolts are tight and properly seated
• Check that there is no interference between the trailing arm and other components throughout the suspension travel
• Test drive the vehicle at low speed in a safe area and listen for any unusual noises
• Check for proper tracking and handling; vehicle should drive straight without pulling
• Re-torque all trailing arm bolts after 50-100 miles of driving
• Inspect trailing arm bushings periodically for signs of premature wear or movement

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