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    2002 BMW 325I 2.5L EFI DOHC 6cyl

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    Ball Joint - Lower and Upper

    Inspect/Test/Service/Replace

    To find out if the ball joint is loose beyond manufacturer's specifications, use an accurate measuring device. Most load carrying ball joints have a wear limit of 0.060" of vertical movement. But some joints can have as much as 0.200" movement and still be within specified limits.

    The following checking procedures demonstrate the use of a dial indicator. The dial indicator is a precision instrument and should be handled carefully to prevent damage. The mounting procedure for the checking tool might vary depending on the style of ball joint used on the vehicle. Manufacturer's tolerances can be axial (vertical), radial (horizontal), or both. To conduct these checks, follow these procedures.

    Typical Radial Check

    For a radial check, attach a dial indicator to the control arm of the ball joint being checked. position and adjust the plunger of the dial indicator against the edge of the wheel rim nearest to the ball joint being checked. slip the dial ring to the zero marking. move the wheel in and out and note the amount of ball joint radial looseness registered on the dial.

    Typical mounting of a dial indicator for a radial check. Courtesy of Moog Automotive, Inc.

    Measuring the Lower Ball Joint Radial Movement on a MacPherson Strut Front Suspension

    • Raise the front suspension with a floor jack and place jackstands under the chassis at the vehicle's lift points.
    • Grasp the front tire at the top and bottom and rock the tire inward and outward while a friend visually checks for movement in the front wheel bearing. If there is movement, adjust or replace the wheel bearing.
    • Position a dial indicator against the inner edge of the rim at the bottom. Preload and zero the dial indicator.
    • Grasp the bottom of the tire and push outward.
    • With the tire held outward, read the dial indicator.
    • Pull the bottom of the tire inward and be sure the dial indicator reading is zero. Adjust the dial indicator as required.
    • Grasp the bottom of the tire and push outward.
    • With the tire held in this position, read the dial indicator.
    Art courtesy of Delmar - Thomson Learning.
    • If the dial indicator reading is more than specified, replace the lower ball joint.

    Typical Axial Check

    For an axial check, first fasten the dial indicator to the control arm, then clean off the flat on the spindle next to the ball joint stud nut. Position the dial indicator plunger on the flat of the spindle and depress the plunger approximately 0.350 inch. Turn the lever to tighten the indicator in place. Pry the bar between the floor and tire. Record the reading.

    Typical mounting of a dial indicator for an axial check. Courtesy of Moog Automotive, Inc.

    If the ball joint looseness reading on the dial indicator exceeds manufacturer's specifications, the ball joint should be replaced. When the load-carrying ball joints are on the upper control arm (spring mounted on the upper arm), raise the vehicle by its frame using support tools to unload the ball joints and hold them in their normal position. To determine the condition of the nonload-carrying (or follower) ball joint, vigorously push and pull on the tire, while watching the ball joint for signs of movement. Refer to the manufacturer's specifications for tolerances.

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