Radius Arm

Remove and replace the radius arm (also called control arm) on the front suspension of a 2007 Ram 3500 4WD with 5.9L Cummins diesel engine.

Warnings

Tools required

Parts

• Radius arm assembly × 1 — Use OEM specification or equivalent heavy-duty aftermarket
• Radius arm bushings (front and rear) × 1 — Usually included with radius arm assembly
• Radius arm mounting bolts and hardware × 1 — Use OEM specification

Preparation

1. Park vehicle on level ground and engage parking brake
2. Chock rear wheels securely
3. Loosen front wheel lug nuts while vehicle is on ground (do not remove)
4. Lift front of vehicle using floor jack at frame rail
5. Support vehicle with heavy-duty jack stands under frame rails behind radius arm mounting point
6. Remove front wheel on side being serviced
7. Apply penetrating oil to all radius arm mounting bolts and allow to soak for 15-30 minutes
8. Take photos of radius arm positioning and hardware orientation for reference during reassembly

Procedure

1. 1

   Support front axle assembly
   Position a floor jack under the front axle housing near the wheel hub area to support the axle weight. Raise jack until it just contacts the axle but does not lift the vehicle. This prevents the axle from dropping when the radius arm is disconnected and maintains suspension geometry.
2. 2

   Disconnect track bar if necessary
   If the track bar interferes with radius arm removal on your specific configuration, disconnect it from the axle bracket. Remove the track bar-to-axle mounting bolt and swing the track bar out of the way. Mark orientation for reassembly.
3. 3

   Remove radius arm-to-axle bracket bolt
   Locate the front mounting point where the radius arm connects to the front axle bracket. This is typically a large through-bolt with a nut on the opposite side. Use a wrench to hold the nut while using a breaker bar and socket to remove the bolt. The bolt passes through the radius arm bushing. Remove bolt completely and retain hardware.
   ⚠Bolt may be seized in bushing sleeve. Do not force excessively or bushing may twist in radius arm.
4. 4

   Remove radius arm-to-frame bracket bolt
   Locate the rear mounting point where the radius arm connects to the frame bracket. This is another large through-bolt assembly. Support the radius arm with one hand or a secondary support while removing this bolt. Use a wrench to hold the nut and a breaker bar to remove the bolt. The radius arm may pivot slightly as tension is released.
   ⚠Radius arm will become free once this bolt is removed. Ensure it is supported to prevent it from falling.
5. 5

   Remove radius arm from vehicle
   With both mounting bolts removed, carefully maneuver the radius arm out from between the axle and frame. You may need to pivot or angle the arm to clear surrounding components. Inspect the removal path for any brackets, brake lines, or wiring that may interfere. Set the old radius arm aside for comparison with the new part.
6. 6

   Inspect mounting points and bushings
   Examine the frame bracket and axle bracket for cracks, wear, or damage. Check for elongated bolt holes or deformed metal. Inspect the bushing bores in both brackets for wear or corrosion. Wire brush all mounting surfaces and threads clean. If installing a new radius arm with bushings already pressed in, verify bushings are properly seated and oriented. If reusing radius arm, inspect bushings for cracking, deterioration, or separation from the arm.
7. 7

   Install new radius arm to frame bracket
   Position the new radius arm into the frame bracket at the rear mounting point. Align the bushing with the bracket holes. Insert the mounting bolt from the outboard side and thread the nut onto the bolt finger-tight. Do not torque at this time. The vehicle weight must be on the suspension before final torquing to prevent bushing wind-up.
8. 8

   Install radius arm to axle bracket
   Maneuver the forward end of the radius arm into position at the front axle bracket. You may need to use the floor jack to adjust axle height slightly to align the holes. Insert the mounting bolt through the axle bracket and radius arm bushing. Thread the nut onto the bolt finger-tight. Again, do not torque at this time.
9. 9

   Reconnect track bar if removed
   If the track bar was disconnected in step 2, reconnect it to the axle bracket now. Insert the mounting bolt and install the nut finger-tight. This will also be torqued with vehicle weight on suspension.
10. 10

    Lower vehicle to load suspension
    Carefully remove the floor jack from under the axle. Lower the vehicle from the jack stands until the tires just touch the ground but the jack stands are still supporting most of the weight. This loads the suspension bushings in their normal operating position. Bounce the front end a few times to settle the suspension.
11. 11

    Torque all mounting bolts
    With the suspension loaded, torque all radius arm mounting bolts to manufacturer specifications. Without specific torque values provided, refer to a factory service manual for this critical specification. Radius arm fastener torque differs between the axle end and frame end on this platform and often includes a torque-plus-angle sequence, so DO NOT GUESS - verify exact values from the factory service manual before torquing. Torque front and rear radius arm bolts, and track bar bolt if removed. Use a torque wrench and tighten in a consistent pattern. Use a 1/2" drive torque wrench sized to cover the verified radius arm fastener spec (up to at least 250-300 ft-lbs), as radius arm fasteners require torque approaching or exceeding 250 ft-lbs (270-300 ft-lbs), making a 0-250 ft-lb torque wrench insufficient.
    ⚠️Radius arm bolts are critical safety components. Improper torque can result in suspension failure and loss of vehicle control. Obtain proper torque specifications from factory service manual before proceeding.
12. 12

    Complete final installation
    Raise vehicle fully and remove jack stands. Install wheel and hand-tighten lug nuts in a star pattern. Lower vehicle completely to ground. Torque wheel lug nuts to specification (approximately 145 ft-lbs for this vehicle, verify against factory service manual) in a star pattern using a torque wrench.

Reassembly

1. Double-check that all fasteners are properly torqued with suspension loaded
2. Verify no tools or parts were left in the wheel well or under vehicle
3. Confirm brake lines, ABS wiring, and other components are properly routed and not pinched
4. Test steering for full range of motion before driving

Verification

• Perform a visual inspection under the vehicle to confirm radius arm is properly seated in both brackets
• Check that all mounting bolts are tight and properly torqued
• Bounce the front end and listen for any unusual noises or clunks indicating loose components
• Test drive at low speed in a safe area and verify steering feels normal with no pulling or vibration
• Have alignment checked and adjusted by a professional shop - radius arm replacement will affect caster and may affect other alignment angles
• Re-torque all fasteners after 50-100 miles of driving and again after 500 miles

More procedures for this vehicle