This procedure covers the removal and replacement of the front radius arm (also known as the lower control arm) on a 2015-2020 Ford F-150 with the 5.0L V8 Coyote engine.

Warnings

Tools required

Parts

• Radius arm (lower control arm) × 1 — Use OEM specification or equivalent
• Cotter pin for ball joint × 1 — Use OEM specification

Preparation

1. Park vehicle on level, solid surface and engage parking brake
2. Place wheel chocks behind rear wheels
3. Loosen front wheel lug nuts while vehicle is on ground (do not remove)
4. Raise front of vehicle with floor jack at designated lift point
5. Support vehicle securely with jack stands under frame rails
6. Remove front wheel on side being serviced
7. Spray all fasteners with penetrating oil and allow to soak for 10-15 minutes if vehicle has significant rust or corrosion

Procedure

1. 1

   Access the radius arm
   Locate the radius arm (lower control arm) which runs from the frame mounting points to the steering knuckle. Inspect the working area and ensure you have clear access to both the frame-side mounting bolts and the ball joint connection at the knuckle.
2. 2

   Disconnect sway bar link if necessary
   If the sway bar link interferes with radius arm removal, disconnect it from the lower control arm. Hold the link shaft with an Allen key to prevent spinning, then remove the lower nut. Support the link and move it aside.
   Torque spec

   Sway Bar Link76 Nm (56 lb-ft)
3. 3

   Remove ball joint cotter pin and loosen nut
   Locate the ball joint castle nut where the radius arm connects to the steering knuckle. Use pliers or a cotter pin tool to remove and discard the cotter pin. Loosen the ball joint nut but do not remove it completely yet - leave it threaded on a few turns to protect the threads.
4. 4

   Separate ball joint from knuckle
   Using a ball joint separator or pickle fork, break the taper connection between the ball joint stud and the steering knuckle. Apply pressure with the tool while tapping with a hammer if necessary. Once the joint pops free, remove the castle nut completely and lower the radius arm away from the knuckle.
   ⚠The control arm may drop suddenly when the ball joint separates. Keep hands and feet clear of the pivot area.
5. 5

   Support the radius arm
   Place a floor jack or wooden block under the outer end of the radius arm to support its weight. This prevents the arm from falling and makes installation of the new arm easier.
6. 6

   Mark alignment reference
   Before removing the frame-side bolts, mark the position of any alignment cams or eccentric washers with a paint pen or marker. This will help maintain approximate alignment when installing the new radius arm.
7. 7

   Remove front frame mounting bolt
   Locate the front radius arm mounting bolt at the frame bracket. This is typically the larger of the two frame attachment points. Use an 18mm socket and wrench to remove the bolt completely. Note the orientation of any washers or bushings.
8. 8

   Remove rear frame mounting bolt
   Remove the rear radius arm mounting bolt from the frame bracket using appropriate socket and wrench. The radius arm should now be free to remove. Carefully lower and remove the radius arm from the vehicle, noting the position of all bushings and hardware.
9. 9

   Inspect and clean mounting points
   Clean the frame mounting brackets with a wire brush, removing any rust, dirt, or debris. Inspect the frame brackets for cracks, damage, or excessive wear. Check that the mounting surfaces are flat and clean.
10. 10

    Install new radius arm to frame
    Position the new radius arm into the frame brackets, aligning it with your reference marks from step 6. Insert the front and rear mounting bolts through the frame brackets and radius arm bushings. Thread the bolts by hand but do NOT torque at this time - leave them finger tight.
    ℹ️Control arm bolts must remain loose until vehicle weight is on the wheels to prevent bushing bind and premature failure.
11. 11

    Connect ball joint to knuckle
    Raise the outer end of the radius arm using the floor jack to align the ball joint stud with the hole in the steering knuckle. Insert the ball joint stud into the knuckle and install the new castle nut. Torque the nut to specification, then advance the nut to the next castle slot if necessary to align the cotter pin hole. Install a NEW cotter pin and bend the ends to secure.
    Torque spec

    Ball Joint Nut110 Nm (81 lb-ft)
12. 12

    Reconnect sway bar link
    If the sway bar link was disconnected in step 2, reconnect it to the radius arm. Hold the link shaft with an Allen key and torque the nut to specification.
    Torque spec

    Sway Bar Link76 Nm (56 lb-ft)
13. 13

    Reinstall wheel and lower vehicle
    Install the wheel and hand-tighten the lug nuts in a star pattern. Lower the vehicle carefully using the floor jack until the full weight of the vehicle is on the wheels, but keep the jack stands in place as a safety backup.
14. 14

    Torque control arm bolts with vehicle loaded
    With the vehicle weight on the wheels and suspension at normal ride height, torque both the front and rear radius arm frame mounting bolts to specification. This is critical for proper bushing life and suspension geometry.
    ⚠Torquing control arm bolts with suspension unloaded will cause bushing failure within a few thousand miles.
    Torque spec

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

    Final torque wheel lug nuts
    Remove jack stands and lower vehicle completely to the ground. Torque all wheel lug nuts to specification in a star pattern using a torque wrench.
    Torque spec

    Wheel Lug Nuts169 Nm (125 lb-ft)

Reassembly

1. Ensure all fasteners are torqued to specification with control arm bolts torqued at ride height
2. Verify new cotter pin is properly installed and secured in ball joint castle nut
3. Double-check that wheel lug nuts are torqued in star pattern

Verification

• Test drive vehicle at low speed in a safe area and listen for any unusual noises from the front suspension
• Check for proper steering response and verify vehicle tracks straight
• Have a professional wheel alignment performed as soon as possible, as radius arm replacement will affect camber and caster settings
• After 50-100 miles, re-check torque on control arm bolts and wheel lug nuts

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