This subject has come up many times on this forum.
The Mark V was the first Jaguar model to have ball joint front suspension, and they used most of the same parts for XK120.
Jaguar initially made the Mark V and XK120 with Morganite bronze cups and grease fittings on the lower ball caps.
Then came one of those “seemed like a good idea at the time” moments in engineering, when they attempted to come up with a greaseless design cup called Ferrobestos and eliminated the grease fittings.
Thus worn lower ball joints became a chronic problem with XK120, and probably Mark VII. The bulk of the wear takes place in the lower ball joints, not the upper.
So then they went back to the bronze cups and grease fittings. Later models have nylon cups.
Referring to the Mark VII parts catalogue…
C.3025 is Morganite, the bronze cup or socket.
C.4714 is the Ferobestos fiber cup or socket.
C.3023 is the Cap containing Ball Socket (with hole for grease nipple.
C.3023/1 is the Cap containing Ball Socket (without hole).
C.3362 is the grease nipple (67-1/2 deg).
To figure out what was going on back in the day, we have to compare the Mark V, Mark VII, XK120 and XK140 parts catalogues and the Service Bulletins. It appears that after Mark V was winding down in 1951, Jaguar believed they could eliminate the grease fitting and use the fiber cup, at the beginning of Mark VII production and after 399 120’s had been built. Then they changed back to the bronze and grease fittings, initially on the Mark VII after only 970 cars, and at some point on the 120, though failing to note this in the parts catalogue. I recall some of you with later 120’s reported you have the grease fittings and bronze cups, and they are in the 140 book. But 679187 from Nov '51 and 681114 from May '53 did not have them. We can only blame Heynes for second guessing his own engineering, and then third guessing his second guess.
My 120 did not have grease fittings originally so I added them when I did my ball joints. I used the 67 degree angled fittings so I can get to them without removing the wheels.
I found it was easiest to do this job with the stub axle carrier upside down in a bench vise.
If yours are original there may be a steel ring in there, called a spigot in
the manual. This often gets destroyed removing it, but the new cup will not
need it. You punch out the old cup with a punch through the grease fitting
hole.
Fit the new cup and ball, put on the cap, then make a rough measurement of the gap.
Put in the appropriate amount of shims, then put on the cap again tight. If
the ball is loose, take out a shim and try again. If the ball is tight, put in a shim and try again.
The spec on end float varies between sources, anywhere from .010" to
“eliminate all end float”, and the shims come in .002" increments anyway, so
I allow a smidgen.