Ball joints can be checked for wear while the wheel
is supported, as shown in figures 8-16 and 8-17. Axial
play or tolerance, also called vertical movement, is
checked by moving the wheel straight up and down.
The actual amount of play in a ball joint is measured
with a dial indicator. Figure 8-18 shows the dial
indicator clamped to the lower control arm. The dial
indicator tip rests against the leg of the steering
knuckle. With a pry bar. try to raise and lower the
steering knuckle. If you use too much force, the ball
joint may give you a false reading. You want to
measure the movement of the wheel and ball joint, as
the joint is moved up to the LOAD position. Note the
movement as indicated on the dial indicator.
Figure 8-16.Support points for checking ball joints in
various front suspension systems using coil springs.
Rocking the wheel in and out at the top and bottom
checks radial play or tolerance. This action also is
known as horizontal movement. Grasp the tire at the
top and bottom, and try to wobble it. However, now we
are assuming that the wheel bearings have been
checked and either adjusted or properly tightened.
Therefore, we are now checking the horizontal
movement of the ball joints. Some manufacturers do
not accept horizontal movement as an indicator of ball
The actual specifications for allowable wear limits
of the ball joints are listed in the manufacturers service
manual. Refer to the specifications for the vehicle you
are checking. Any ball joint should be replaced if there
is excessive play.
Ball joint replacement can usually be done without
removing the control arm. Generally, place the vehicle
on jack stands. Remove the shock absorber and install
a spring compressor on the coil spring. Unbolt the
steering knuckle and separate the steering knuckle and
Figure 8-17.Support points for checking ball joints in front
suspension system using torsion bars.