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The original, rebuildable lower ball joint is assembled with shims to provide a properly snug fit between the ball and
the socket. It should be noted that these shims are intended to provide a proper fit at assembly, not for removing the
slop from a worn joint. If a joint develops slop, it should be rebuilt with new parts or replaced entirely, not merely
readjusted.
The ROM, Section 60.15.04, describes re-shimming the lower ball joint without disconnecting it from the stub axle
carrier, but frankly this is questionable; you will have a difficult time determining the correct snugness of that ball joint
without being able to manipulate the ball pin by hand. Besides, you probably need to replace the gaiter while you’re in
there anyway, so use the overhaul procedure in 60.15.13 instead.
When rebuilding the lower ball joint, don’t lose the shims that come out. Although the QH kit includes shims, there
may not be enough to provide all new shims.
Bernard Embden suggests: “I found that, under pressure, grease was spitting out between the shim and one lower ball
cup. Putting a straight edge against the ball joint surface at the knuckle revealed an uneven surface which had to be
trued up before completing the rebuild. I believe that these lower ball joints are subject to a lot of abuse as the car runs
over debris, etc. Checking with a straight edge should be part of any rebuild.”
It is recommended that you trial-assemble the ball joint dry (no grease) in order to establish the correct shimming. It’s
amazing how grease can make a sloppy joint feel tight.
Thoroughly grease the ball and socket parts prior to final assembly. Although the joint has a zerk fitting, its use is no
substitute for proper greasing at assembly.
LOWER BALL JOINT SUBSTITUTION: As mentioned above, the lower ball joint from the XJ40, part number
CAC9937, will replace the original ball joint on the XJ-S perfectly. This ball joint is made by Lemförder in Germany;
the Lemförder part number is 030 260 004 834. It has no grease fitting, it’s not rebuildable and the gaiter is not
considered replaceable (not available separately) -- but it’s still the better choice in ball joints! The gaiter built onto the
Lemförder ball joint is an excellent design, shaped like a bellows to allow the joint to move back and forth without
stressing the rubber or pulling open a gap. It also has metal spring rings at both ends to hold it snugly to the joint.
So, your choice seems to be: replace the gaiters on the original ball joints every five years, or replace the entire joint
with the XJ40 part and forget about it for some time -- perhaps ten years anyway.
The XJ40 lower ball joint also provides a bit more clearance for aftermarket wheels.
When installing the XJ40 ball joint, the shims from the original joint are not used. They were only needed to provide
internal clearance in the rebuildable joint.
When replacing the rebuildable ball joint with the XJ40 ball joint, note that the upper ball seat of the original ball joint
must be removed. It’s a metal ring, and it actually looks like it could be an integral part of the hub carrier, but it’s not;
it’s pressed in from below. Charlie Marino suggests using the old ball pin as a tool for removing it; “I placed the ball
end of the ballpin on the upper seat from the top and hit downward into the seat with a hammer. About 4 medium hits
drove the seat out through the bottom of the stub axle carrier.”
UPPER BALL JOINT REPLACEMENT: The official repair manual calls for “Steering Joint Taper Separator JD.24”,
but we don’t need no steenking separator! Put the car on jackstands and remove the wheel. Put a jack and block of
wood under the lower ball joint and jack it enough that the rubber bumpers on the upper A-arm are not touching the
subframe. Loosen the nut on the upper ball post several turns, but do not remove it. Lower the jack so that the rubber
bumpers sit on the stops and the full spring force is applied to separating the joint. If you’re lucky and the previous
mechanic used anti-seize compound on the taper, you’ll hear a pop as it comes loose. If more difficult, a little judicious
tapping on the side of the hub carrier may help.
Make sure to note where the shims are located between the arms and the ball joint. Even if you plan to have the car
aligned, at least it will drive better on the way to the shop. The shims are supposed to lift right out, but they weren’t