Buick LeSabre 1965 Service Manual page 390

6-24
REAR AXLE, 46, 48, 49000 SERIES
relatively slight on straight ahead
driving. Noise produced by these
gears will be most pronounced on
turns.
(3) Pinion Bearing Noise. Rough
or brinelled pinion bearings pro-
duce a continuous low pitch whir-
ring or scraping noise starting
at relatively low speed.
(4) Ring and Pinion Gear Noise.
Noise produced by the ring and
pinion gear set generally shows
up as drive noise, coast noise,
or float noise.
(a) Drive noise is most evident on
constant acceleration through the
speed range.
(b) Coast noise is most evident
when car is allowed to coast
through the speed range with
throttle closed.
(c) Float noise is most evident
while just barely holding the car
speed constant on a level road at
any given speed.
(d) Drive, coast, and float noises
will be very rough and irregular
if the differential or pinion shaft
bearings are rough, worn, or
loose, and will vary in tone with
speed.
c. Check for Propeller Shaft
Vibration
Objectionable vibrations at high
speed (65 MPH or higher) may be
caused by a propeller shaft that is
out of balance. Out of balance
may be caused by a bent shaft.
To determine whether the pro-
peller shaft is causing vibration,
drive car through the speed range
and note car speed at which vi-
bration is most pronounced. Shift
transmission into low range and
drive car at same engine speed
as when vibration was most pro-
nounced in direct drive, and note
the effect on vibration.
To determine the required engine
speed, divide car speed by the
transmission gear ratio, using
2.48 for automatic. Example: if
vibration is most pronounced at
65 MPH in direct drive, the same
engine speed would be produced
fin
in low range at = 26 MPH.
If the vibration is still present at
the same engine speed whether in
direct drive or in the lower gear,
then the propeller shaft is not out
of balance. If the vibration de-
creases or is eliminated in the
lower gear, then the propeller
shaft is out of balance and should
be removed for correction.
d. Oil Leaks
It is difficult to determine the
source of some oil leaks. When
there is evidence of an oil leak
at these locations, the probable
cause is as follows:
(1) A leak coming from the bot-
tom edge of the brake backing
plate is caused by either a leak-
ing wheel bearing seal or a leak-
ing brake cylinder. The feel and
smell of the leaking oil will help
determine the type leak to expect.
(2) Oil coming from between the
rear pinion flange slinger and the
carrier is caused by a leaking
pinion seal. Oil coming out around
the pinion nut is caused by a de-
fective " O " ring seal between the
drive pinion and the pinion flange.
Even after the point of leakage
has been determined, it is hard to
tell whether the oil is leaking
past the lip of the seal or past
the O.D. of the seal. Therefore it
is a good idea to make sure the
leak is stopped by using a non-
hardening s e a l i n g compound
around the O.D. of the new seal.
6 - 1 3 REMOVAL AND I N -
STALLATION OF REAR
AXLE ASSEMBLY
It is not necessary to remove the
rear axle assembly for any nor-
mal repairs. The axle shafts and
the carrier assembly can easily
be removed from the car, leaving
the rear axle assembly in place.
However, if the housing is dam-
aged, the rear axle assembly can
be removed and installed using
the following procedure.
a. Removal of Rear Axle
Assembly
1. Raise rear of car and support
securely using car stands under
both frame side rails.
2. Mark rear universal joint and
pinion flange for proper reas-
sembly. Disconnect r e a r uni-
versal joint by removing two
U-bolts. (On 49000, mark flanged
ball stud yoke and rear pinion
flange for proper alignment at
reassembly. T h e n disconnect
rear CV joint from rear axle
by removing four pinion flange
bolts.) Push rear propeller shaft
forward as far as possible, then
wire it to the upper control arm
frame bracket to support it out of
the way.
3. Disconnect brake hose at sup-
port bracket. Cover hose and
brake pipe openings to prevent
entrance of dirt.
4. Disconnect p a r k i n g brake
cables. Unclip each cable at two
places, disengage from guides,
pull each cable free and lay-out
forward from rear wheels.
5. Place a jack under center of
rear axle housing and raise until
shock absorbers are compressed
slightly. Disconnect shock ab-
sorbers at lower ends.
6. Disconnect track bar at axle
end on 49000.
7. Disconnect upper control arm
(or arms, 46, 48000) at axle end.
8. Lower jack slightly and dis-
connect lower control arms at
axle end.
9. Lower jack from under axle
housing and remove.
10. Roll rear axle assembly out
from under car.