GENERAL FITTING REMINDERS
3
INFORMATION BALL AND ROLLER BEARINGS
CAUTION: Never refit a ball or roller
bearing without first ensuring that it is in a
fully serviceable condition.
1.Remove all traces of lubricant from bearing
under inspection by washing in a suitable
degreaser; maintain absolute cleanliness
throughout operations.
2.Inspect visually for markings of any form on
rolling elements, raceways, outer surface of
outer rings or inner surface of inner rings. Reject
any bearings found to be marked, since any
marking in these areas indicates onset of wear.
3.Holding inner race between finger and thumb of
one hand, spin outer race and check that it
revolves absolutely smoothly. Repeat, holding
outer race and spinning inner race.
4.Rotate outer ring gently with a reciprocating
motion, while holding inner ring; feel for any
check or obstruction to rotation, and reject
bearing if action is not perfectly smooth.
5.Lubricate bearing generously with lubricant
appropriate to installation.
6.Inspect shaft and bearing housing for
discolouration or other marking suggesting that
movement has taken place between bearing and
seatings. (This is particularly to be expected if
related markings were found in operation 2).
7.Ensure that shaft and housing are clean and free
from burrs before fitting bearing.8.If one bearing assembly of a pair shows an
imperfection it is generally advisable to replace
both with new bearings; an exception could be
made if the faulty bearing had covered a low
mileage, and it could be established that
damage was confined to it only.
9.When fitting bearing to shaft, apply force only to
inner ring of bearing, and only to outer ring when
fitting into housing, as shown above.
10.In the case of grease lubricated bearings (e.g.
hub bearings) fill space between bearing and
outer seal with recommended grade of grease
before fitting seal.
11.Always mark components of separable bearings
(e.g. taper roller bearings) in dismantling, to
ensure correct reassembly. Never fit new rollers
in a used outer ring, always fit a complete new
bearing assembly.
CLUTCH
1
FAULT DIAGNOSIS CLUTCH ASSEMBLY CONDITIONS
For the clutch to operate correctly it is important the
following conditions are satisfied:-
·The primary shaft (15) must be free in the
crankshaft spigot bush (17).
·The friction plate (2) must be able to slide easily on
the splines on the primary shaft (15), to a position
where it does not contact either the flywheel or the
pressure plate.
·The friction plate must not be distorted or the
linings contaminated with oil, which may cause it to
stick or continue to run in contact with the flywheel
or pressure plate.
A number of faults can develop in the operation of the
clutch for a variety of reasons and most faults are due
to normal wear at high mileage. Problems can also
occur if the unit has been renewed by an unskilled
operator.
Recognising and diagnosing a particular clutch fault is
therefore of paramount importance in ensuring that
the problem is rectified at the first attempt.
Problems which develop in the clutch are as follows:-
·Clutch spin/drag
·Clutch slip
·Clutch judder/fierceCLUTCH SPIN - DRAG
Symptoms
Clutch spin is that, with engine running and clutch
pedal depressed, the gears cannot be immediately
engaged without making a grinding noise. This
indicates the clutch is not making a clean break.
However, if the clutch pedal is held depressed for
several seconds the friction plate will eventually break
free from the engine and the gear will engage silently.
Clutch spin as it becomes more severe develops into
clutch drag, making the silent engagement of a gear
impossible, regardless of how long the pedal is held
depressed.
CLUTCH SLIP
Symptoms
Clutch slip is most evident climbing a hill or when the
vehicle is moving off from stationary with a heavy
load. As the clutch is released, slip occurs between
the engine and the transmission, allowing the engine
speed to increase without a corresponding increase in
vehicle speed.
Clutch slip can develop to the stage where no power
is transmitted through the clutch as the pedal is
released.
CLUTCH JUDDER - FIERCE
Symptoms
Clutch judder or fierce engagement, like slip, is most
likely to occur when the vehicle is moving off from
stationary. As the clutch pedal is released the vehicle
will move rapidly or in a series of jerks, which cannot
be controlled even by careful operation of the clutch
by the driver.
It should be noted that a vehicle may display all the
symptoms or any combination of the symptoms
described, depending on the driving conditions vehicle
load and operating temperatures.
