Lower Control Arm - Front

Remove and replace the front lower control arm on a 2009 Aston Martin DB9, including disconnection of ball joint, sway bar link, and control arm mounting bolts.

Warnings

Tools required

Parts

• Lower control arm assembly × 1 — Use OEM specification
• Lower ball joint castle nut × 1 — Replace if cotter pin holes damaged
• Control arm bushing bolts (if separate) × 2 — Inspect for thread damage

Preparation

1. Park vehicle on level surface and engage parking brake
2. Loosen wheel lug nuts while vehicle is on ground
3. Raise front of vehicle and support securely on jack stands under manufacturer-specified jacking points
4. Remove front wheel on side being serviced
5. Spray all control arm fasteners, ball joint nut, and sway bar link hardware with penetrating oil and allow to soak for 10-15 minutes

Procedure

1. 1

   Support lower control arm
   Position a floor jack under the lower control arm near the ball joint to support the arm and suspension load. Raise jack just enough to take slight pressure off the control arm (do not lift vehicle). This prevents the arm from dropping suddenly when fasteners are removed.
2. 2

   Disconnect sway bar link from control arm
   Locate the sway bar end link connection (verify whether it attaches to the lower control arm or steering knuckle per factory documentation for this vehicle). Hold the internal shaft with an Allen key to prevent rotation, then remove the lower mounting nut using a socket. Note the orientation of any washers or bushings. Lower the sway bar link away from the control arm.
   Torque spec

   Sway Bar Link Nuts55 Nm (41 lb-ft)
3. 3

   Remove lower ball joint castle nut
   Remove the lower ball joint retaining fastener at the steering knuckle (verify design against factory documentation — may be a self-locking nut or pinch bolt rather than a castle nut and cotter pin). Using the correct socket, remove the fastener completely. Replace with new hardware per manufacturer specification. Note: Identify the lower ball joint retention method at the steering knuckle by consulting the factory workshop manual for this vehicle (do not assume a pinch-bolt clamp or a castle nut without verification). Remove the identified fastener completely per OEM documentation. Replace any single-use fastener as specified by the manufacturer. Note: Remove the lower ball joint retaining nut at the steering knuckle (verify against OEM documentation whether this is a castle nut with cotter pin or a self-locking nyloc nut). Using a socket, remove the nut completely. Replace self-locking nuts with new; reuse a castle nut only if threads and cotter pin holes are undamaged.
   Torque spec

   Lower Ball Joint Nut63 Nm (46 lb-ft)
4. 4

   Separate ball joint from knuckle
   Insert a ball joint separator tool (press-type preferred over a pickle fork to avoid boot damage) between the lower control arm and steering knuckle at the ball joint taper. Apply steady pressure to break the taper fit. Do not hammer directly on threads or use excessive force that could damage the knuckle bore. Once separated, support the knuckle to prevent stress on brake hoses and ABS wiring.
   ⚠Do not allow the steering knuckle to hang unsupported. Secure with wire or a secondary jack to prevent damage to brake lines and ABS sensor wiring.
5. 5

   Locate and access control arm mounting bolts
   Identify the two control arm mounting points to the subframe: typically a front bushing bolt and a rear bushing bolt. The front bolt passes through the front bushing housing, while the rear bolt secures the rear bushing to the subframe. Clean any dirt or corrosion from bolt heads and surrounding areas.
6. 6

   Remove front control arm mounting bolt
   Using a breaker bar and appropriate socket, remove the front control arm mounting bolt that passes through the front bushing and subframe bracket. This bolt is typically oriented horizontally. Support the control arm with the floor jack as the bolt is removed. Note the orientation of any washers or spacers.
   Torque spec

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

   Remove rear control arm mounting bolt
   Remove the rear control arm mounting bolt that secures the rear bushing to the subframe. This may require maneuvering the jack position slightly to provide clearance. Once this bolt is removed, the control arm will be free from the vehicle.
   Torque spec

   Control Arm Bolts165 Nm (122 lb-ft)
8. 8

   Remove control arm from vehicle
   Lower the floor jack slowly while guiding the control arm away from the subframe and knuckle. Maneuver the arm out through the wheelwell opening. Inspect the removed arm for bushing wear, cracks, or deformation. Check mounting points on subframe for damage or excessive wear.
9. 9

   Prepare new control arm for installation
   Compare new control arm to old unit to verify correct part. Inspect ball joint boot for integrity and ensure ball joint stud moves freely with appropriate resistance. Prepare bolt threads per OEM specification. Do not apply anti-seize to critical suspension fasteners unless the manufacturer requires it, as this alters clamp load for a given torque; use thread locker only if specified, applied to clean, dry threads. Ensure bushings are properly seated in control arm housings. Note: Verify OEM thread preparation requirements. For critical suspension fasteners, threads should generally be clean and dry (or treated with the specified thread locker). Do not apply anti-seize unless specified, as it alters torque-to-clamp-load relationship.
10. 10

    Install control arm to subframe
    Position the new control arm into the subframe mounting locations. Align the rear bushing with its mounting bracket first, then insert the rear mounting bolt by hand. Do not fully tighten. Align the front bushing and insert the front mounting bolt by hand. Ensure all washers and spacers are positioned as noted during removal. Thread bolts in enough to hold arm securely but do not torque at this stage.
    ℹ️Control arm bolts must not be torqued until vehicle weight is on suspension. Leave bolts hand-tight plus 2-3 turns only.
    Torque spec

    Control Arm Bolts165 Nm (122 lb-ft)
11. 11

    Connect ball joint to steering knuckle
    Raise the floor jack under the control arm to bring the ball joint stud into alignment with the knuckle bore. Insert the ball joint stud into the knuckle taper. Install the ball joint retaining fastener (self-locking nut, castle nut, or pinch bolt per factory specification) and torque to specification. If a castle nut and cotter pin are used, align the nut slots with the stud hole and install a new cotter pin, bending the ends to secure. Always use new retaining hardware. Note: Reinstall the ball joint retention fastener per the method identified in removal (pinch bolt or nut) and torque to OEM specification. If a cotter-pinned castle nut is used, align the slots with the stud hole and install a new cotter pin, bending the ends to secure.
    Torque spec

    Lower Ball Joint Nut63 Nm (46 lb-ft)
12. 12

    Reconnect sway bar link
    Position the sway bar end link to the lower control arm mounting point. Install any washers or bushings in their original orientation. Thread the mounting nut onto the link shaft. Hold the internal shaft with an Allen key and torque the nut to specification.
    Torque spec

    Sway Bar Link Nuts55 Nm (41 lb-ft)
13. 13

    Install wheel and lower vehicle
    Mount the wheel, align the bolt holes with the hub, and thread the wheel bolts by hand to prevent cross-threading. Snug the wheel bolts in a star pattern but do not torque fully yet. Remove jack stands and carefully lower the vehicle until full weight is on the suspension but wheels are still accessible for final torquing.
14. 14

    Torque control arm bolts under load
    With the vehicle weight now on the suspension (wheels on ground or simulated load), torque both control arm mounting bolts to specification. Torque the front bolt first, followed by the rear bolt. This ensures bushings are not pre-loaded in the wrong position, which would cause premature wear.
    ⚠Failure to torque control arm bolts under load will result in bushing failure and poor handling characteristics.
    Torque spec

    Control Arm Bolts165 Nm (122 lb-ft)
15. 15

    Final torque wheel lug nuts
    Torque all wheel bolts to specification in a star pattern. Perform a final check of all fasteners installed during this procedure.
    Torque spec

    Wheel Lug Nuts89 Nm (66 lb-ft)

Reassembly

1. Reassembly is covered in the installation steps above
2. Ensure all fasteners are torqued to specification
3. Verify cotter pin is properly installed and secured in ball joint castle nut

Verification

• Start vehicle and turn steering wheel full lock in both directions while stationary to verify no binding or interference
• Test drive vehicle at low speed and verify no abnormal noises from front suspension
• Check for proper steering response and straight-line tracking
• Re-torque wheel lug nuts after 50-100 miles of driving
• Schedule four-wheel alignment immediately after completion, as control arm replacement will alter suspension geometry

Related trouble codes on this vehicle

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