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

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1 Inspect / Service / Test / 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. Moog Automotive, Inc.

2 Testing Lower Ball Joint Radial Movement MacPherson Strut Suspension Raise the vehicle, lift at body / frame 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.

3 Position a dial indicator against the inner edge of the rim at the bottom. Preload and zero the dial indicator.

4 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 the outward position, read the dial indicator. If the dial indicator reading is more than specified, replace the lower ball joint.

5 Typical Axial / Vertical Check For an axial check, first lift by lower control arm, test with a pry bar between the floor and tire to see if there is any vertical / axial movement. (Do Not Lift Strut Suspension In This Manner) For Macpherson strut suspension lift vehicle by the body supports at frame or designated rocker panel support positions and test the same way.

6 Fasten a 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 inch. Turn the lever to tighten the indicator in place. Typical mounting of a dial indicator for an axial check. Moog Automotive, Inc. If the ball joint looseness reading on the dial indicator exceeds manufacturer's specifications, the ball joint should be replaced.

7 Testing Upper Ball Joints 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 nonloadcarrying (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.

8 Wear Indicating Lower Loading Bearing Ball Joint When inspecting a lower ball joint that is load bearing such as a lower control arm with coil spring. Keep the vehicle on the ground, look to see if the part that the grease fitting threads into is protruding or not. If the part recedes into the ball joint housing the ball joint is defective and needs to be replaced, if it protrudes slightly check OEM specifications, it is potentially good.

9 Wheel Alignment Thrust Alignment: The front wheels are aligned to the rear drive axle. Drive direction of the rear axle is known as the thrust angle. 4 Wheel Alignment: All 4 wheels are aligned to the geometric centerline. 2 Wheel Alignment: The front wheels are aligned with the centerline and assumes the rear wheels are too. Camber Is how much the wheel tilts inward (Negative) or outward (Positive). Correct camber improves stability, helps suspension life and minimizes tire wear.

10 Caster Is how much the vertical centerline angle is tilted forward (Negative) or backward (Positive). Correct caster improves stability, steering center return and cornering.

11 Toe Is whether or not the tires are directly parallel to each other. Correct toe reduces scuffing and improves tire wear. If the tires are pointed in towards each other it is considered Positive toe angle, if pointed away from each other it is considered Negative toe angle.

12 Toe Out or Turning Radius When the vehicle is turning the toe angle needs to change slightly to allow the vehicles wheels to travel properly, the outside wheel is actually taking a longer path and the angle needs to accommodate for this.

13 Steering Axis Inclination Is the left / right angle of the strut.

14 Chassis Height Chassis height is also critical to properly alignment, refer to OEM specifications.

15 Upper & Lower Control Arm Bushing Inspection Look for missing rubber, look for large splits or cracks, see if it is off center. On a short/long arm inspection visually inspect from under hood. Very small weather cracks or splits are okay provided they do not extend into contact areas. It can be very difficult to see the lower bushings, use a pry bar to attempt to move the bushing from side to side. A good bushing will move right back into place, a worn or bad bushing will likely stay to the position the pry bar has moved it to.

16 Dry Park Test / Lash With the engine off and the key in the unlock position check for steering wheel freeplay. Move the steering wheel left and right witness tire movement, feel for any looseness in tie rod ends, steering box, steering rack or any support bushings.

17 The steering rack can also be tested with a pry bar to check for support bushing wear.

18 The top of the strut needs to checked for looseness as well try to move the center left / right / in /out.

19 The strut itself may have vertical movement, test by trying to lift strut.

20 Some vehicles have I-Beam suspension, test the I-Beam bushings with a pry bar to see if loose checking for movement.

21 I-Beam suspensions also have a radius arm, inspect the bushings for looseness, shiny spots can indicate a weak bushing.

22 Tie Rod Inspection Grab tire on left and right side, push on each side, feel for looseness, if looseness is experienced it may be the inner or outer tie rod. Outer tie rod testing, hold tie rod end in palm of your hand and squeeze to see if axial / vertical movement.