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.

Set both arms to the correct length for your lift height before installing. Fine-tuning can be done after a professional alignment.

Torque Specifications

⚠ 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 — Set Caster, Then Final Torque

With the vehicle at ride height and full weight on the suspension, set caster before final torque of the cam bolt:

💡 What is Caster? Caster is the angle of the steering axis — specifically, how far the upper ball joint is behind the lower ball joint when viewed from the side. If you drew a line through the center of the upper and lower ball joints, that line should be tilted rearward 3.5–5 degrees from vertical. Caster is what keeps your truck tracking straight on the road and causes the steering wheel to return to center after a turn. If your truck wanders on the highway or pulls every time it hits a dip in the road, you likely need more caster.

How to Measure Caster:

• Place a digital angle finder on the machined flat surface on top of the steering knuckle, around the upper ball joint — this surface is designed for this measurement
• The reading should be between 3.5 and 5 degrees
• Apoc Industries recommends no less than 3.5 degrees — factory Ford spec is approximately 3.5 degrees
• For trucks running offset wheels, Apoc recommends approximately 5 degrees for best on-road tracking and steering return

Adjusting Caster:

• Use the alignment cam bolts on the axle-side mount for fine caster adjustment
• If more adjustment range is needed than the cam bolts provide, adjust the arm length in or out to reach the desired caster angle, then use the cam bolts for final fine-tuning
• Once caster is set to your preference, torque the alignment cam bolts to 158 ft-lbs

Then torque all remaining fasteners to spec:

• Factory frame pivot bolt: 222 ft-lbs
• Factory upper pivot point bolt: 222 ft-lbs
• Cam alignment bolt (axle-side): 158 ft-lbs — after caster is set
• 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