There is a procedure using a huge pliers for checking balljoints. This
procedure checks the movement in the joint in the vertical direction,
however the outer ball joint is supposed to control movement
horizontally (affecting caster and camber). Hence the test with the big
pliers does not check the direction in which control matters. Further,
the rear mount of the control arm is in a rubber bushing which does
allow some motion in the horizintal plane which affects caster and
camber (just think of the inner balljoint as the pivot point). So we
have some slop in the control of the caster and camber, and in my
opinion this is by design. For me the real question is what is the real
tolerance for the balljoint play, and how is it measured, given the play
in the system? How do you know that the balljoints need replacing?
Using the huge-pliers-test both joints are showing some motion after
only 25000 miles, yet the dealer feels only one joint has slight play.
I have two new control arms to install so I plan to wait a bit. If I
recall right, Bentley manual says when you get knocks in the suspension,
but does not say much else. I have discovered the knocks can be coming
from the stabilizer link.
If anyone knows the story on these balljoints, I am very interested in
I suspect it was BMW's intent for some fuzziness on the alignment,
otherwise why use that rubber bushing?