This procedure covers the removal and replacement of the front radius arm (lower control arm) on a 2015-2020 Ford F-150 with 3.5L EcoBoost engine.

Warnings

Tools required

Parts

• Radius arm (lower control arm) × 1 — Use OEM specification
• Ball joint castle nut × 1 — Use OEM specification
• Cotter pin × 1 — Use OEM specification

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 at frame rail positions
4. Remove wheel and tire assembly
5. Spray penetrating oil on ball joint nut, control arm bolts, and mounting hardware if vehicle is from rust-prone area

Procedure

1. 1

   Support lower suspension
   Position floor jack under the lower radius arm near the ball joint to support the weight of the suspension. Raise jack just enough to lightly compress the suspension and relieve tension on components. This prevents sudden drops when disconnecting parts.
2. 2

   Disconnect sway bar link
   Locate the sway bar link connection to the radius arm. Use an Allen key to hold the shaft while loosening the lower nut with a 21mm socket. Remove the nut and disconnect the sway bar link from the radius arm. The link can remain attached to the sway bar.
   Torque spec

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

   Remove ball joint cotter pin and nut
   Remove the cotter pin from the ball joint castle nut at the steering knuckle. Use a 24mm socket to remove the ball joint nut completely. Do not reuse the cotter pin or castle nut.
   Torque spec

   Ball Joint Nut101 Nm (75 lb-ft)
4. 4

   Separate ball joint from knuckle
   Insert ball joint separator tool between the radius arm and steering knuckle. Strike or turn the tool according to manufacturer instructions to break the taper fit. The ball joint stud should pop free from the knuckle. Lower the jack slightly to allow the radius arm to drop away from the knuckle.
   ⚠Ball joint may release suddenly. Keep hands clear of pinch points between control arm and knuckle.
5. 5

   Mark alignment cam position
   At the front mounting point of the radius arm to the frame, mark or photograph the position of any alignment cam or eccentric washer relative to the frame bracket. This helps maintain approximate alignment during reinstallation.
6. 6

   Remove front radius arm mounting bolt
   Using a 19mm socket and breaker bar, remove the front mounting bolt that secures the radius arm to the frame bracket. This is the forward-most attachment point. Remove the bolt completely and note the position of any washers or spacers.
   Torque spec

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

   Remove rear radius arm mounting bolt
   Using a 19mm socket and breaker bar, remove the rear mounting bolt that secures the radius arm to the frame bracket. This bolt passes through the rear bushing of the radius arm. Remove the bolt completely.
   Torque spec

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

   Remove radius arm
   With both mounting bolts removed and ball joint disconnected, maneuver the radius arm out of the frame brackets. You may need to rotate or angle the arm to clear the frame, sway bar, and other suspension components. Lower the jack as needed to create clearance.
9. 9

   Clean mounting surfaces
   Use a wire brush to clean the frame mounting bracket surfaces, removing any rust, dirt, or debris. Inspect the mounting bolt holes in the frame for damage or elongation. Clean the ball joint taper bore in the steering knuckle.
10. 10

    Install new radius arm to frame
    Position the new radius arm into the frame brackets. Insert the front and rear mounting bolts through the frame brackets and radius arm bushings. Install bolts finger-tight only. Align any cam marks noted during removal. Do NOT torque bolts at this time.
11. 11

    Connect ball joint to knuckle
    Raise the floor jack to lift the radius arm and align the ball joint stud with the hole in the steering knuckle. Insert the stud into the knuckle taper. Thread the new castle nut onto the ball joint stud and tighten to specification using a torque wrench.
    Torque spec

    Ball Joint Nut101 Nm (75 lb-ft)
12. 12

    Install new cotter pin
    Install a new cotter pin through the castle nut and ball joint stud. If the cotter pin hole does not align, tighten the nut further (never loosen) until the next slot aligns with the hole. Bend the cotter pin ends to secure.
13. 13

    Reconnect sway bar link
    Position the sway bar link into the mounting hole on the radius arm. Install the retaining nut, holding the shaft with an Allen key while tightening the nut to specification with a torque wrench.
    Torque spec

    Sway Bar Link Nuts55 Nm (41 lb-ft)
14. 14

    Reinstall wheel and lower vehicle
    Install the wheel and tire assembly. Thread lug nuts by hand, then snug them in a star pattern. Lower the vehicle until the tires just touch the ground but the suspension is still slightly unloaded. Remove jack stands.
15. 15

    Torque control arm bolts with weight on wheels
    Lower the vehicle completely so full weight is on the wheels. Bounce the suspension several times to settle components. Using a torque wrench, torque both the front and rear radius arm mounting bolts to specification. This is critical for proper bushing alignment and longevity.
    ⚠Torquing control arm bolts without vehicle weight will cause premature bushing failure.
    Torque spec

    Control Arm Bolts165 Nm (122 lb-ft)
16. 16

    Torque wheel lug nuts
    Using a torque wrench, tighten all wheel lug nuts to specification in a star pattern.
    Torque spec

    Wheel Lug Nuts156 Nm (115 lb-ft)

Reassembly

1. Repeat procedure for opposite side if replacing both radius arms
2. Ensure all fasteners are torqued to specification
3. Verify cotter pin is properly installed and secured

Verification

• Test drive vehicle at low speed and verify no abnormal noises or vibrations
• Check for proper steering response and straight-line tracking
• Have front end alignment performed by qualified technician within 50 miles of repair
• Re-check all fastener torques after 100 miles of driving

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