Why can’t one just do the fulcrum
bearings if that’s all that needs work? I can’t see how they are
related at all, except that they are both installed in the same hub
Well, I guess theoretically it can be done that way. However, the
whole shebang is something of an interference fit, and it takes a bit
of coordination to get it all together without damaging the seals or
shims. Since it is really easy to pull the hub off, it might be easier
to pull that to make things easier to manuever.
Maybe we’re having a semantics problem. Removing the hub carrier
from the car is a lead pipe cinch, and obviously would be recommended
for R&R of the fulcrum bearings. But rebuilding the hub bearings
requires a puller of some sort, and there have been several
discussions here that it was NOT easy. If one’s hub bearings are OK,
I don’t see why one would touch them when working on the fulcrum
I have opened up three fulcrum assemblies on three different Jags (my
XJ6, my XJ-S and another) and each had the parts in a different
sequence, none of them matching the various and sometimes ambiguous
Can you give some examples of the various assembly sequences? Were
any of them actually harmful?
See the above. Failure is caused either because things stay sealed
and eventually the rollers wear grooves in the races…
The failure mode of roller bearings that don’t rotate but rather
remain stationary and turn back and forth just a hair is called
“false brinelling”, because it looks much like a Brinell hardness
test (lay roller on track, smack with hammer) until you look at it
with a microscope. Under magnification, the actual Brinell dimple
still has the original machining marks at the bottom, since they were
merely pushed downward. The false brinelling, though, is a pattern
of wear at individual spots, so the bottoms of the dimples are smooth.
The secret of avoiding false brinelling is to make the rollers small
enough that the small movements of the bearing make them move more
than the space between them, spreading the wear more uniformly over
the race. If that is impractical, you either need to go with a
bushing instead, or just plan on replacing the bearings often.
This is a real troublemaker on headset bearings on bicycles. The
fork turns only a hair, even during steep turns. When the wear
causes false brinelling dimples, the handling gets all screwed up –
the steering seems to “snap” from position to position. And you can
only tell when there is weight on the bike, since only the LOWER
bearing suffers the wear – if you pick the bike up and turn the fork
back and forth, it seems fine because there’s no weight on it and
it’s rolling on the upper bearing. The only way to test is to hold
the front wheel off the ground, pull up on the handlebars while
pushing down on the frame as hard as you can, and turn back and forth
– and if you can feel ANY snappage, replace the headset.
…or, and more
likely, when water gets in there and things get rusty.
Ah, that brings up a possibility. There are seals to keep water out
of the assembly, but water might still be able to sneak in between
the shaft and the oil seal track. And considering where this thing
is, it’s actually possible to park the car in a puddle and have this
thing immersed. Perhaps it’d be a good idea to apply some sealant to
the ID of the oil seal track when assembling. Considering how the
thing is assembled, though – using a dummy shaft, and pushing the
dummy shaft out by inserting the real shaft – I dunno how to get
sealant to stay in place.
BTW, this entire job requires a dummy shaft. I presume nobody has
too much trouble coming up with such, but we might ask for ideas
here. What have people used to make that dummy shaft?
I used a stainless steel bar of suitable diameter.
Hah! Like we’ll all have one of those laying around!
The shaft I used was slightly
smaller in OD than the fulcrum shaft, and over a foot long.
Didn’t you have to cut it down to the length of the hub carrier?
After all, if longer than the hub carrier would work, you’d just use
the actual fulcrum shaft.
doesn’t matter that the diameter is less than the fulcrum shaft, as
long as it is large enough to keep the parts in alignment.
Yeah, I can see that.
– Kirbert | Palm’s Postulate:
| If anything is to be accomplished,
| some rules must be broken.
| – Kirby Palm, 1979On 25 Oct 2000, at 12:33, JGN wrote: