PS Magazine - TB 43-PS-694
PS, The Preventative Maintenance Monthly
ISSUE 694
SEPTEMBER 2010
10
PS 694
SEP 10
Dear Half-Mast,
A mechanic recently came to me and said he needed to replace his
HMMWV’s ball joints. I asked him, “Why are you replacing them? What
makes you think they are bad?” To my surprise, he answered, “Someone told
me if I could move the halfshaft with my hand it was no good.”
Now, you and I both know that’s not the right answer! Can PS please
clarify the correct way to inspect HMMWV upper and lower ball joints? I’m
concerned that money is wasted when good parts are mistakenly replaced.
Mr. J.H.
Dear Mr. J.H.,
Glad to help you with that.
To get the guidance you need for maintaining your HMMWV’s ball joints
correctly, take a look at your HMMWV’s operator and maintenance manuals.
The -10 tells you to visually check halfshaft CV boots and ball joint boots for
presence, rips, tears or cuts.
And the -20 tells you to check for proper operation of ball joints using these
steps:
1.
Chock rear wheels front and back.
2.
Raise front wheels about two inches off the ground and support on a jack stand.
For lower ball joints:
a.
Mark a line across the head of the
top bolt holding the steering arm cover.
Make sure the mark is parallel to the
lower control arm.
b.
Put a pry bar between the cover
control arm and geared hub.
You can also check for looseness in
the lower ball joints by grasping the
bottom of tires and attempting to move
tires in and out. If tire movement at the
bottom outer edge of tires is
1
/
2
inch or
more, replace the lower ball joints.
c.
Set a 6-in ruler upright between
the lower control arm and the marked
screw.
d.
Push down the pry bar to try to move
the hub.
e.
Measure movement in the hub
assembly. If movement is more than
1
/
8
inch, replace the lower ball joint.
b.
Measure any movement at the top
outer edge of tire. Replace upper ball
joints if tire movement
is
3
/
8
inch or more.
For upper ball joints:
a.
Check for looseness of upper ball
joints by grasping the top of tires and
attempting to move tires in and out.
how to Inspect
ba joints!
HMMWV…
how to Inspect
ba joints!
Check
extent
of tire
movement
at
bottom
of tires
Check
extent
of tire
movement
at
top
of tires
See if hub moves when you push
down pry bar at this location
Geared hub
Control arm
whatcha
gonna
dO?
I’m gonna see if
your ball joints
are any good!
694.10-11.indd
1-2
7/26/10
11:48:24 AM
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