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.
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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.
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 the outward position, read the dial indicator.
If the dial indicator reading is more than specified, replace the lower ball joint.
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.
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 0.350 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.
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.
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.
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.
Caster
Is how much the vertical centerline angle is tilted forward (Negative) or backward
(Positive). Correct caster improves stability, steering center return and cornering.
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.
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.
Steering Axis Inclination
Is the left / right angle of the strut.
Chassis Height
Chassis height is also critical to properly alignment, refer to OEM specifications.
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.
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.
The steering rack can also be tested with a pry bar to check for support bushing wear.
The top of the strut needs to checked for looseness as well try to move the center left /
right / in /out.
The strut itself may have vertical movement, test by trying to lift strut.
Some vehicles have I-Beam suspension, test the I-Beam bushings with a pry bar to see
if loose checking for movement.
I-Beam suspensions also have a radius arm, inspect the bushings for looseness, shiny
spots can indicate a weak bushing.
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.