Upper Control Arm - Rear

This procedure covers the removal and replacement of the rear upper control arm on a 4WD Dodge Ram 2500 with the 5.9L Cummins diesel engine.

Warnings

Tools required

Parts

• Rear upper control arm × 1 — Use OEM or quality aftermarket specification
• Cotter pin × 1 — 1/8" x 1.5" cotter pin

Preparation

1. Park vehicle on level surface and engage parking brake
2. Chock front wheels securely
3. Loosen rear wheel lug nuts while vehicle is on ground
4. Raise rear of vehicle with floor jack at differential or frame
5. Support frame securely with jack stands on both sides
6. Remove rear wheel on side being serviced
7. Spray all control arm mounting bolts and ball joint nut with penetrating oil, let soak 10-15 minutes

Procedure

1. 1

   Support the rear axle
   Position a floor jack under the rear axle housing near the wheel hub being serviced. Raise jack just enough to make light contact with the axle to support it and prevent it from dropping when the control arm is disconnected. Do not lift the axle, just support it.
2. 2

   Remove ball joint cotter pin
   Locate the upper control arm ball joint where it connects to the axle housing knuckle. Use needle nose pliers to straighten and remove the cotter pin from the ball joint castle nut. If the cotter pin is corroded, cut it with diagonal cutters.
3. 3

   Remove ball joint nut
   Using a 21mm socket, remove the castle nut from the upper ball joint stud. Keep the nut for reference when installing the new control arm. The ball joint stud will remain tapered into the axle knuckle at this point.
4. 4

   Separate ball joint from axle
   Insert a ball joint separator or pickle fork between the control arm and axle knuckle mounting point. Strike the tool with a hammer to break the taper fit. Alternatively, use a pickle fork and hammer to wedge between the components. The ball joint stud will pop free from the knuckle. Note: If reusing the ball joint boot, avoid damaging it with the separator tool.
   ⚠The control arm may spring away when the ball joint separates. Keep hands clear of pinch points.
5. 5

   Remove frame mounting bolts
   Locate the two control arm mounting bolts at the frame bracket. These are 18mm head bolts passing through the control arm bushings. Using an 18mm socket and breaker bar, remove both bolts completely. The front bolt may require angling the socket due to clearance restrictions. Support the control arm as you remove the second bolt.
6. 6

   Remove control arm
   Pull the control arm away from the frame bracket and maneuver it out of the wheel well area. Inspect the frame mounting bracket for damage, cracks, or excessive rust. Wire brush the bolt holes and mounting surfaces clean.
7. 7

   Inspect and prepare new control arm
   Compare the new control arm to the old unit to verify correct fitment. Check that bushings are properly seated and that the ball joint moves freely through its range of motion. If the ball joint has a grease fitting, apply grease until fresh grease appears at the boot seal.
8. 8

   Install control arm to frame
   Position the new control arm into the frame bracket, aligning the bushing holes with the bracket holes. Insert both frame mounting bolts by hand. Thread bolts in 2-3 turns but do NOT tighten at this time. The bushings must be torqued with vehicle weight on the suspension.
9. 9

   Connect ball joint to axle
   Pivot the control arm down and align the ball joint stud with the hole in the axle knuckle. You may need to use the floor jack under the axle to raise or lower the axle slightly for alignment. Push the ball joint stud through the knuckle hole until it is fully seated.
10. 10

    Install and torque ball joint nut
    Thread the castle nut onto the ball joint stud by hand, then tighten to the specified torque using a 21mm socket and torque wrench. Align the castle nut slots with the hole in the stud. If slots don't align, tighten further (never loosen) until a slot aligns. Insert a new cotter pin through the castle nut and stud, then bend the ends to secure.
11. 11

    Reinstall wheel
    Place the wheel back onto the hub and thread all lug nuts by hand. Tighten lug nuts snug in a star pattern using the correct lug socket, but do not torque to final specification yet.
12. 12

    Lower vehicle to torque control arm bolts
    Remove the floor jack from under the axle. Carefully lower the vehicle from the jack stands until the full weight of the vehicle is resting on all four wheels. With the suspension at normal ride height, torque both control arm frame mounting bolts to specification using an 18mm socket and torque wrench.
    ℹ️Torquing control arm bolts at ride height is critical for bushing longevity. Torquing with suspension hanging will cause premature bushing failure.
13. 13

    Final torque wheel lug nuts
    With the vehicle on the ground, torque all wheel lug nuts to specification (approximately 130 ft-lbs) in a star pattern using the correct lug socket and torque wrench. Double-check that all lug nuts are properly torqued.

Reassembly

1. If replacing both sides, repeat the entire procedure for the opposite side
2. Remove wheel chocks after completion
3. Test drive vehicle at low speed to verify proper installation before highway use

Verification

• Verify all fasteners are torqued to specification with vehicle at ride height
• Check that the new cotter pin is properly installed and bent
• Bounce the rear of the vehicle and listen for any unusual noises from the suspension
• Inspect for proper wheel alignment - vehicle should track straight with no pull
• Schedule a professional alignment check, as control arm replacement will affect camber and toe settings

Related trouble codes on this vehicle

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