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4-6
GROUP
4-REAR AXLE
REAR AXLE TROUBLE SYMPTOMS AND POSSIBLE CAUSES
(cont.)
EXCESSIVE REAR AXLE NOISE
EXCESSIVE REAR AXLE
BACKLASH
BEARING NOISE
Defective bearings will produce
a whine that is constant in pitch
and varies with vehicle
speed.
This
fact will help distinguish between
bearing and/ or gear noise.
1. Pinion bearing noise can be
identified as a
constant grinding
noise. Pinion bearings are rotating
at a higher speed than differential
side bearings or axle shaft bear-
ings. The noise is most noticeable
at a slight pull between 18 to 26
miles per hour.
2. Wheel bearing noise may be
confused with rear axle
noise.
To
differentiate between wheel bear-
ings and rear axle, drive the car
on a smooth road at medium low
speed. With traffic permitting, turn
the car sharply right and left.
If
noise is caused by wheel bearings,
the
no~se
will increase on the de-
fective
bearing
because
of
side
loading.
3. Side bearings will produce a
constant grinding noise of a slower
nature than pinion bearing, (side
bearing noise cannot be determined
by the wheel bearing test), but will
be in the same frequency as axle
shaft bearings.
GEAR TOOTH CONTACT
PAnERN CHECK
Paint the gear teeth and roll a pattern
as
described on Page 4 -15
.
After diag-
nosing the tooth pattern as explained
here, make
the
appropriate adjustments
as outlined in 4-17.
In making a final gear tooth con-
tact pattern check, it is necessary
to recognise the fact that there are
three different types of gear set,
hunting, non-hunting and
partial
non-hunting.
Each type is deter-
wns in the differential case will be
and ftoat noise differs with speed
most pronounced on turns. A con-
and if the noise is very rough and
tinuous whine under a light load
irregular; worn,
rough
or loose
between 20 and 35 miles per hour
differential or pinion shaft bearings
indicates rough or brinnelled pinion
are indicated. Remove, disassemble,
bearings.
If
the tone of drive, coast
and inspect the axle.
Excessive backlash in the
axle
lash between the drive pinion and
driving parts may be
caused by
ring gear, excessive backlash in the
worn axle shaft splines, loose axle
differential
gears,
or bearings which
shaft ftange
nuts,
loose
U-joint
are worn or out of
adjustment.
ftange mountings, excessive. back-
DRIVE SIDE
COAST SIDE
DESIRABLE PATTERN'
SHIM
CORR~CT
BACKLASH CORRE CT
TOE
FIG. 5
-Ideal Tooth Pattern
mined by the ratio and the number
of teeth in the gears. The non-hunt-
ing and partial non-hunting types
can be identified by marks on the
pinion and ring gear teeth.
See Page; 4-2 for complete identification
specifications.
FIG. 6
-Acceptable
Hunting Gear Pattern
THE IDEAL TOOTH PAnERN
Fig. 5 shows the ideal tooth pat-
tern. This pattern is not a rigid
standard but merely a general rule.
In general, desirable tooth pat-
terns should have
the
following
characteristics:
T OE
(a) The drive pattern should be
fairly well centred on the tooth.
(b) The coast pattern should
be
centred on the tooth but may be
slightly toward the toe.
FIG. 7
-Unacceptable
Non-Hunting Pattern-
Centre-Toe-Centre
(c) Some clearance between
th~>
pattern and the top of the tooth is
desirable.
(d) There should be no hard lines
where the pressure is high.
The individual gear set need not
conform exactly to the ideal pat-
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