The wheel hubs of the
vintage Land-Rover have long posed challenges as
regards the effective retention of lubricating oil.
Even the factory as much as admitted this fact when
years ago they issued a service bulletin directing
technicians to replace the 90-weight oil with wheel
bearing grease. Given that so many Land-Rovers suffer
difficulties in this area, it will undoubtedly prove
useful to take a close look at this common problem.
To begin with, it
should be observed that the factory, as usual, got it
right the first time, incorporating the finest
lubrication strategy into their original design.
Extreme pressure liquid lubricant (EP90) is the
superlative system for assuring the longevity of
wheel bearings on vehicles used in the adverse
conditions of punishing off-raod operation. Lubricant
of this sort, by its very nature, continually
cleanses the wheel bearings, whereas wheel bearing
grease simply retains debris and contaminants and
moves them repeatedly over close-tolerance bearing
races and rollers, thus assuring the virtual
impossibility that dirt can be detected or removed.
The gravitational settling out of debris is simply
infeasible. "Ninety weight" [EP90], on the
other hand, readily yields evidence of contamination
when examined, warning servicing personnel
immediately of any foreign debris. It also changes
color to various shades of light brown when
contaminated by water. Particulates can readily be
detected manually or visually, swept with a magnet,
or strained to determine the presence of material
potentially damaging to the bearings. It is also
self-draining and tends to carry off a greater
percentage of contaminants when drained. For these
reasons it is superior to grease, and, in my
estimation, should be used wherever possible.
However, some human
beings favour the ever-tantalising, simplistic short
cut, and resort to wheel bearing grease. It goes
without saying that save in the most extreme of
circumstances it does not leak; hence its great
popularity. There is, however, another way. Consider
the following: When diagnosing leaks in the area of
the wheel hub, either front or rear, two presenting
symptoms typically come to the attention of our
service department: 1. oil leaking onto the road
wheel, visible from outside the vehicle, and: 2. oil
contaminating the brake drum and shoes. Rarely does
lubricating oil find its way to the outside of the
backing plate of the brake drum, except in small
telltale quantity at the bottom of the backing plate.
Let us, therefore,
divide the problem into two parts. Oil leaking to the
outside of the wheels is typically either or the
other of two problems. One is that the felt-rubber
seal [and hence the hub cap] is leaking, the other is
that the driving member bolts are loose. Considering
the first problem, the felt-rubber seal, let us look
first at why it is leaking. Typically leaks occur
because the felt-rubber seal is very old, compressed
or hard [rarely the root cause], or secondarily
because the half shaft [axle] has been allowed to
loosen in the driving member. This is often caused
because the castellated nut on the end of the half
shaft "becomes loose" by virtue of wear of
the mating parts: the end of the half shaft and/or
the driving member itself. Secured by a cotter pin,
the castellated nut cannot actually rotate loose, but
instead, not keeping it snug over long miles and/or
years radically accelerates the rate at which the
male and female splines of the hub can work against
each other, causing excessive friction and wear of
the mating parts. Half-shaft and driving member
splines can actually wear against each other to the
point that the splines will eventually wear entirely
off. Integral to this process: the felt-rubber seal
will be degraded mechanically to the point of
leaking.
For these reasons it
is probably the better part of wisdom to disassemble
the half-shaft/driving member about once every
ten-to-fifteen thousand miles to inspect, clean and
reassemble the parts in question. At the same
interval it is always wise to inspect the half-shaft
splines, at both the inner and outer ends, for
possible signs of wear or impending failure. 
It is always good drill to
replace the felt-rubber seal, re-tighten the
castellated nut, install a new o-ring under the hub
cap, and possibly also seal the hub cap with R.T.V.
Silicone sealant. Hub caps which are badly distorted
should be replaced, because if they have become
stretched they may not stay in place, and will almost
certainly leak.
Another cause of
leaking wheel hubs stems from the six drivng member
securing bolts working loose which allows the driving
member to rotate slightly each time the Land-Rover is
accelerated or decelerated. This can happen for one
of several reasons. One is simply that the lock
washers have lost their spring tension and allowed
the bolts to work loose. Another is that the bolts
have become stretched. Yet another is that the
splines have become so worn that shock is imparted to
the driving member every time power is applied or
withdrawn to the drive line, thus forcing the driving
members loose prematurely. Actually, excessive wear
anywhere in the drive line is potentially problematic
to associated parts within the drive line. This
condition causes many half-shafts to fail
prematurely, as well. These problems rarely appeared
with Land-Rovers twenty or thirty years ago, when the
hubs had never been stripped down, or had perhaps
seen only one service cycle, but it is much more
prevalent today in Land-Rovers with higher
accumulated miles. Whatever the cause, let us look at
some practical remedies.
First, obviously, to
diagnose potential faults arising in the hubs, a full
strip-down is called for. Begin by removing the hub
caps. These can be tenacious in the best of
circumstances. I typically use a brake adjusting
spoon or "heel bar", [frequently two are
required, placed opposite each other] but any type of
strong prying device will eventually overcome the
tenacious grip of the most obstinate of caps, and
obstinate is the definitive term!! Use the
surrounding driving member bolts for fulcrums. Next
remove the cotter pin from the nut at the end of the
half shaft. Do NOT at this point loosen the
castellated nut! Instead, use the nut as a diagnostic
tool by turning it clockwise, counting the
"flats" carefully to ascertain the extent
of wear or looseness. The thread count is 16-to the
inch, so each flat, then, represents one sixth of
that amount, or .267 inches of wear. While the
precise amount is perhaps not critically important,
when observed over time it becomes a useful relative
unit of measure to track the degree of wear.
Now remove the
castellated nut and withdraw the driving member
itself. Do not try to coax it with a hammer, but use
instead a stout pry bar, using any of the surrounding
five wheel studs [preferably with nut replaced on the
stud to protect the threads] for a fulcrum. Then
remove the half-shaft. If it is stubborn, the inner
splines may be twisted in the differential. Having
withdrawn the driving member, return it to the outer
end of the half-shaft. Place the half shaft securely
in a vise and attempt to rotate the driving member on
the shaft. No discernible wear or play should be
detectable, either radially or laterally. Remember
that any appreciable wear in the drive line
potentially imparts shock to the balance of the drive
line and accelerates deterioration of associated
componentry. Crystallization of the steel is very
common in half-shaft breakage. In sub-critical
vehicle usage, wear of the splines may simply be
noted for interest, but in Land-Rovers which are used
in demanding and/or critical situations, such defects
should be corrected to forestall catastrophic
consequences. Genuine Land-Rover half shafts,
typically the best available, are none too good
themselves, and non-genuine shafts can break within a
astoundingly short period of use.
I recall the case of a
business colleague who drove his Land-Rover in
extreme conditions with a weak half-shaft. The
so-named half-shaft snapped in a moment of
exceptional difficulty, turning the land-Rover
sideways to the slope, causing it to roll to a
punishing near-death.
Back to the subject at
hand. If wear is detected in the splined interface
between the half-shaft and driving member it should
be borne in mind that each one will cause its
counterpart to wear more aggressively, and also to
impart potentially troublesome shock to other more
expensive components such as the spider gears in the
differential, and even the shafts and gears of the
transmission. Accelerated wear begets accelerated
wear. [And premature breakage]. For these reasons,
and others, it is worthwhile bearing these effects in
mind when considering the possible replacement of the
worn components.
Another reason for
leakage at the hubs may be caused by stretched
driving member bolts (Part number 251-323). It is
interesting to note that when factory-fresh Genuine
Land-Rover driving member bolts are torqued to
factory specifications, I have seen such bolts to
stretch on first installation. The shop manual calls
for 30-38 foot-pounds of torque, but I prefer to
tighten them by feel, by hand. These bolts are of the
British Standard variety [BSF], so use a 5/16 BSF
ring spanner [box-end wrench, for you Yanks]. If no
BS spanners or sockets are available, a 19/32"
fractional will do. If over-tightened, the bolts can
snap off in the hub, but they are typically prone to
stretching first. In other words the metallurgy is
not all that it might be. Cheaper non-Genuine bolts
can be even worse!
To inspect the driving
member bolts for damage, first clean them in
solvent......each and every one......and then dry
them off with a shop rag. Now look carefully along
the full length of the threads, noting particularly
the point at which the threads meet the non-threaded
shoulder of the bolt. Observe very carefully the
spacing of the threads to see if any are differently
spaced, one to the next. This is the point at which
stretching always occurs. Stretching can also be felt
by running the fingers up and down the length of the
bolt: a narrower cross section will be felt at the
point where the threaded portion of the bolt
transitions to the plain shank. If stretching is
suspected the bolts should be replaced, as a limited
amount of stretch is possible before breakage occurs.
Lock washers should also be inspected for sharpness
and spring tension and replaced if questionable.
They, of course, prevent the bolts from rotating
loose, at least theoretically, but if worn or tired
they cannot do the job intended. Do pay attention to
the smallest detail; terein may lurk the dread
Achilles heel.!
Now, what of the
sealing, or mating, surfaces of the wheel-bearing hub
and driving member? Many do-it-yourselfers, and a
shameful number of "professional" mechanics
use a hammer to remove stubborn driving members from
the hub, with the regrettable consequence that the
hub or the driving member, or both, become distorted,
and hence unable to seal oil as originally designed.
How to inspect for this injury? First, clean the
suspected culprit[s] in cleaning solvent, and dry
well. Now inspect the inner machined surface of the
driving member, as well as the periphery, for
dimples, swelling or bruises which might have been
imparted by careless, heavy hammer blows. The surface
of the closely-machined face of the driving member
will evidence upset, swelling or distortion of the
steel, which stands proud of the surrounding
material. While this swelling can be removed by
machining, it is probably better to move the
displaced material back to its intended location with
judicious hammer blows. For the uninitiated this
should be attempted only gently at first, using the
smooth flat face of a suitable hammer. Practice on a
piece of scrap wherever possible. Once the majority
of the damaged material has been restored to its
rightful place, clamp the driving member, inner face
upwards, into the soft jaws of a sturdy vise. If your
tool box is bereft of one, purchase a top quality
U.S. mill bastard file. Using this file, carefully
dress down the face of the driving member until it is
entirely flat once again. A high-quality, straight,
new file will also serve as a reliable, if crude,
straightedge. It is characteristic of those
unfamiliar with this procedure to remove rather too
much material, or not to retain the flat, so it would
again constitute time well spent to practice this
somewhat delicate operation on a piece of discarded
material, so as to make ones' first errors on a
non-critical piece. Gently file the entire face of
the driving member until it all shines like silver.
Constrain the file to very flat, even strokes. Remove
any material begrudgingly, but bring the face slowly
and carefully to a consistent overall brightness,
removing only enough metal to achieve this desired
look. Do not remove metal from the inner distance
ring of the driving member, as it constitutes an
important part of the sealing mechanism. To stay
clear of this eventuality, place only the unmilled
side of the file against this surface; this is
precisely the reason a mill file has been called for.
Back in the days when
small Ferrari components were largely hand finished,
Enzo Farrari supplied his factory apprentices with a
sparkling new, virgin vise at the outset of their
internship programme. If they allowed the file to
slip off the work and damage the vise just once, they
were immediately let go from the works!
Now turn to the wheel
hub itself. Has it been similarly damaged by wanton
hammer blows, or the careless hand of the clumsy and
irreverent? If so, as before, move material back to
its place of origin wherever possible, with carefully
placed hammer blows. Should the finished face of the
hub still prove uneven, apply the same treatment with
the mill file until the entire mating surface of the
hub is bright silver. Now try the mating surfaces to
one another, either clamping them in a vise or
utilizing at least three bolts to secure the matng
faces snugly together. If a misfit is suspected, use
a feeler gauge to check for a poor interface. A
discrepancy of only a thousandth or two can easily
cause the hub to leak, so the offending member must
be dressed down to assure a successful restoration.
If a feeler gauge is unavailable, machinists' bluing
applied to one surface of the mating pair will surely
reveal the necessary information to make the
appropriate adjustments. All these efforts, of
course, are indicated only when both male and female
splines are found worthy at the outset.
The hubs should by
this time be ready for reassembly. The factory
originally stipulated HYLOMAR brand gasket cement in
this as well as many other applications. This product
was originally formulated by Rolls Royce, Ltd., and
it is a product eminently worthy of the good name of
the firm. It is, in the world of gasket sealants,
without equal, much like the Rolls itself, and, of
course, like Land-Rover! One of the crowning virtues
of HYLOMAR is that components thereby sealed can be
field-stripped numerous times with loss of neither
gasket nor sealant, and thus returned to service
repeatedly without incident. HYLOMAR is the sealant
of choice with racing and aviation technicians. It
was not originally intended for use in joints where
no gasket was fitted, but so brilliant is its formula
that it will also serve in this application in a
pinch.
When reinstalling the
half-shafts it is not a bad idea to use them as
diagnostic tools to check the differential for
possible excessive wear. Simply reintroduce the half
shafts to the axle and bolt one driving member up to
the hub with two bolts only. Then rotate the opposite
driving member/half-axle by hand, listening and
feeling for any sounds or lumpy feel which the
differential might make. Using the longer half shaft
in the shorter side of the axle for better feel. If
anything but a silky smooth feel is detected it is
probably a good idea to remove the differential for
inspection. If the lube oil is o be drained from the
axle it is a good idea to catch the oil in a
squeaky-clean PYREX glass bowl, being careful, of
course, of the dangers of hot oil! Allow the oil to
settle for a brief time and hold the bowl up high so
as to view the bottom. In this way any steel debris
which has settled will be readily visible. An
overnight's wait may prove even more revealing, but
if time is of the essence, then draw a magnet through
the drainings to see if any metallic debris is
present. It is all too common that the axle case is
not at all, or is insufficiently, cleaned after the
breakup of a half-shaft. This, of course, is
guaranteed to lead to grossly accelerated wear of the
differential gears and bearings. For those unfamiliar
to British Northwest's parts offerings, we supply
magnetic drain plugs for all oil cavities of the
vintage Land-Rover, including the overdrive. In these
times when replacement spares for the Land-Rover are
becoming more scarce, this can prove both a
diagnostic and an economic benefit.
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