2005-2022 Ford Super Duty Adjustable Radius Arms Installation Guide
2005–2022 Ford Super Duty Adjustable Radius Arms
Installation Guide | Apoc Industries | Part Number: AP-900-302
Fits: 2005–2022 Ford F-250, F-350 & F-450 Super Duty (4WD)
865-983-5004 | 9–5 EST | support@apocindustries.com
Kit Includes
- (2) Adjustable radius arms with DOM main tube
- (2) Greaseable flex joints
- Alignment cam bolts
Safety
To ensure safety while installing suspension products, always wear safety glasses and use the correct tools.
Required Tools
- Floor jack and jack stands
- Torque wrench
- Socket set — metric and standard
- Grease gun
- Wheel chocks
- Safety glasses and gloves
Arm Length Chart
Set arm lengths before installation. All measurements are center-to-center. The main tube (longer bar) is the lower/primary radius arm. The upper short bar is the secondary upper link.
| Lift Height | Main Tube (Lower Bar) | Upper Short Bar |
|---|---|---|
| Stock | 34 3/4" | 15 1/16" |
| 2" | 35" | 14 1/2" |
| 3" | 35 3/16" | 14 1/8" |
| 4" | 35 3/8" | 14" |
| 5" | 35 9/16" | 13 9/16" |
| 6" | 35 7/8" | 13 7/16" |
Set both arms to the correct length for your lift height before installing. Fine-tuning can be done after a professional alignment.
Torque Specifications
| Fastener | Torque Spec |
|---|---|
| Factory frame pivot bolt (frame-side) | 222 ft-lbs |
| Factory upper pivot point bolt | 222 ft-lbs |
| Supplied cam alignment bolt (axle-side) | 158 ft-lbs — set caster before final torque |
⚠ Always torque all radius arm bolts with the vehicle at ride height — full weight on the suspension. Torquing with the suspension hanging will preload the bushings and flex joints causing premature wear.
Installation Steps
Step 1 — Prepare the Vehicle
Park on a level surface and set the parking brake. Chock the rear wheels. Loosen the front lug nuts slightly before lifting the vehicle.
Step 2 — Raise the Vehicle and Support on Jack Stands
Use a floor jack to raise the front of the vehicle. Place jack stands beneath the frame rails just behind the radius arm frame mounts and lower the vehicle onto them. Keep a jack under the front axle so you can raise and lower it during installation.
Step 3 — Remove the Front Wheels
Remove both front wheels.
Step 4 — Set Arm Lengths Before Installation
Using the arm length chart above, set both the main tube and upper short bar to the correct center-to-center measurement for your lift height before installing. Lock the adjusters securely. This is much easier to do on the bench than under the truck.
Step 5 — Remove the Factory Radius Arms
Remove the factory radius arm bolts at both the frame and axle side on one side at a time. Note the orientation of the factory arms before removal. Remove the factory arms and set aside.
Step 6 — Install the Apoc Adjustable Radius Arms
- Install the new Apoc radius arm in place of the factory arm, using the factory frame-side pivot bolt and the supplied cam alignment bolt on the axle side
- Thread all bolts by hand — do not torque yet
- Use the floor jack under the axle to raise or lower it as needed to align the bolt holes
- Track bar note: When the axle is at full droop, the track bar will pull the axle off-center. If bolt holes are not aligning, raise the axle closer to ride height with the floor jack and they should line up — this is normal track bar geometry behavior
- Repeat on the opposite side
Step 7 — Grease the Flex Joints
Before lowering the vehicle, pump silicone-compatible grease into all grease fittings on the flex joints until grease appears at the edges.
Step 8 — Reinstall Wheels and Lower to Ride Height
Reinstall the front wheels and hand-tighten the lug nuts. Remove the jack stands and lower the vehicle to the ground so the full weight is on the suspension. Roll the vehicle forward and back a few feet to allow the suspension to settle at true ride height.
Step 9 — Final Torque
With the vehicle at ride height and full weight on the suspension, torque all fasteners to spec:
- Factory frame pivot bolt: 222 ft-lbs
- Factory upper pivot point bolt: 222 ft-lbs
- Cam alignment bolt (axle-side): Set caster to your preference first using the cam bolt, then torque to 158 ft-lbs
- Lug nuts: 165 ft-lbs in a star pattern
Step 10 — Final Inspection
Verify that nothing is rubbing, that brake hoses and ABS sensor wires are not pinched or stretched, and that all hardware is properly torqued before driving.
Post-Installation Instructions
- A professional front-end alignment is required after installation — do not skip this step. The cam bolt allows caster adjustment at the alignment shop for optimal handling and tire wear.
- After driving for 500 miles, re-torque all fasteners and inspect all components visually.
- Grease all flex joint fittings at each oil change interval.
- Before driving, visually inspect all components to ensure they are functioning properly.
Safety Disclaimer
This installation guide is provided for reference purposes. Apoc Industries assumes no liability for improper installation, use of incorrect torque values, or failure to follow all safety procedures. Suspension modifications significantly affect vehicle handling characteristics. Always have suspension work inspected by a qualified mechanic and comply with all local laws regarding vehicle modifications.
Apoc Industries | apocindustries.com | 865-983-5004 | support@apocindustries.com | Document Version: v1.0

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