Upper Control Arm - Rear

This procedure covers the removal and replacement of the rear upper control arm on a 2023 Chevrolet Bolt EUV, including disconnection from the knuckle and frame mounting points.

Warnings

Tools required

Parts

• Rear upper control arm × 1 — Use OEM specification
• Cotter pin × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and engage parking brake
2. Loosen rear wheel lug nuts 1/4 turn while vehicle is on ground
3. Raise vehicle with floor jack at approved lift point
4. Support vehicle with jack stands under frame rails
5. Remove rear wheel completely
6. Spray all fasteners with penetrating oil and allow to soak for 10-15 minutes

Procedure

1. 1

   Support the rear suspension
   Position floor jack under the rear lower control arm or knuckle to support the suspension assembly. Raise jack until it just contacts the component with slight upward pressure. This prevents the suspension from dropping when the upper control arm is disconnected.
2. 2

   Remove ball joint cotter pin
   Locate the upper control arm ball joint nut where it connects to the rear knuckle. Straighten the cotter pin legs using a punch or small drift, then pull the cotter pin completely out and discard. Do not reuse the old cotter pin.
3. 3

   Remove ball joint nut
   Using a 19mm socket, remove the ball joint nut from the upper control arm ball stud. Keep the nut for comparison with the new hardware. Note the number of threads visible on the stud for reference during installation.
   Torque spec

   Ball Joint Nut88 Nm (65 lb-ft)
4. 4

   Separate ball joint from knuckle
   Install ball joint separator tool between the upper control arm and the knuckle. Tighten the separator tool to apply pressure to the ball joint taper. Tap the knuckle boss with a hammer while maintaining pressure to break the taper free. Once separated, remove the separator tool and support the control arm to prevent it from falling.
   ⚠Do not use a pickle fork style separator as it will damage the ball joint boot. Use a proper ball joint separator tool or tie rod separator.
5. 5

   Remove front control arm mounting bolt
   Locate the front mounting bolt that secures the control arm to the frame or subframe. Using a 21mm socket and breaker bar, remove the bolt completely. Note the orientation of any washers or spacers for reinstallation. The bolt may be tight due to thread locker compound.
   Torque spec

   Control Arm Bolts165 Nm (122 lb-ft)
6. 6

   Remove rear control arm mounting bolt
   Using a 21mm socket and breaker bar, remove the rear mounting bolt that secures the control arm to the frame or subframe. Support the control arm as you remove this final bolt to prevent it from falling. Remove the control arm from the vehicle and inspect the mounting points for damage or corrosion.
   Torque spec

   Control Arm Bolts165 Nm (122 lb-ft)
7. 7

   Clean mounting surfaces
   Use a wire brush to clean the mounting bolt holes in the frame and the ball joint taper seat in the knuckle. Remove any rust, debris, or old thread locker compound. Inspect the knuckle taper for damage. If the taper is damaged or elongated, the knuckle must be replaced.
8. 8

   Install new control arm mounting bolts
   Position the new upper control arm into the frame mounting brackets. Install both front and rear mounting bolts by hand, ensuring any washers or spacers are in their correct positions. Thread the bolts in several turns but do not tighten yet. The bolts will be torqued to specification after the vehicle is lowered.
   ℹ️Do NOT torque control arm mounting bolts at this stage. They must be torqued with vehicle weight on wheels.
9. 9

   Connect ball joint to knuckle
   Raise or lower the floor jack supporting the suspension to align the ball stud with the hole in the knuckle. Insert the ball stud into the knuckle taper, ensuring it seats fully. Install the ball joint nut and tighten to specification using a torque wrench. The taper should pull tight as the nut is torqued.
   Torque spec

   Ball Joint Nut88 Nm (65 lb-ft)
10. 10

    Install new cotter pin
    Install a new cotter pin through the hole in the ball stud. The cotter pin should pass through easily. If the slots do not align, tighten the nut slightly (never loosen) until the next slot aligns with the hole. Bend the cotter pin legs to secure it in place, wrapping around the nut.
    ⚠Never loosen the ball joint nut to align the cotter pin hole. Only tighten to the next available slot.
11. 11

    Reinstall wheel and lower vehicle
    Install the rear wheel and thread all lug nuts by hand. Lower the vehicle slowly using the floor jack until the tire just contacts the ground but the suspension is not yet fully loaded. Tighten lug nuts in a star pattern to specification using a torque wrench. Fully lower the vehicle and remove jack stands.
    Torque spec

    Wheel Lug Nuts136 Nm (100 lb-ft)
12. 12

    Torque control arm bolts with vehicle loaded
    With the vehicle weight fully on the wheels and suspension at normal ride height, torque both the front and rear control arm mounting bolts to specification. This ensures the control arm bushings are not preloaded in a twisted position, which would cause premature failure. Use a torque wrench and 21mm socket.
    ⚠This is a critical step. Torquing with suspension hanging will cause bushing failure within months.
    Torque spec

    Control Arm Bolts165 Nm (122 lb-ft)

Reassembly

1. Ensure all fasteners are torqued to specification
2. Verify cotter pin is properly installed and secured
3. Remove floor jack from under suspension

Verification

• Bounce the rear of the vehicle several times and verify no unusual noises from the control arm area
• Verify the ball joint has no play by attempting to move the wheel top-to-bottom with vehicle on ground
• Test drive vehicle at low speed and verify proper handling and no clunking noises over bumps
• Schedule a four-wheel alignment as suspension geometry has been altered

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

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