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TRUNNION: Steering & Suspension Parts Online

The trunnion can be found where the upper or lower control arm attaches to the spindle.

Examples of Trunnion Assemblies


The trunnion was used on older vehicles such as the AMC Rambler, Hudson Jet, and Willys passenger cars.

This part was attached to the upper control arm with steel threaded bushings. The center of the trunnion has a bronze bushing in the center, which slides onto the shaft of the spindle, attaching to the bearing first, with a castellated nut.

The trunnion allows the spindle to rotate when the vehicle is steering, and allows for up-down movement of the control arms at the same time. Trunnion assemblies have been phased out in favor of upper/lower ball joints.

Installation of Trunnion Assembly



See Picture at right

1. Remove the original spindle (A) and control arm as per American Motors shop manual.

2. Disassemble and remove the lower trunnion.

3. Clean the worn thread on the spindle (A) thoroughly.

4. Place the lock washer (B) on the spindle (A) and apply thread locker to the threaded area.

5. Thread the threaded adapter (C) onto the spindle (A) and torque to 60ft lbs.

6. Thread the lock plug (D) in and tighten as tight as possible. (The threaded adapter (C) with the lock plug (D) is to be locked to the spindle and should never turn on the spindle).

7. Thread the trunnion (E) on the threaded adapter (C), then back the trunnion off one full turn.

8. Reassemble the spindle (A), new bushings and control arm as per the American Motors shop manual.

9. Thoroughly grease the unit.