GMC 4000 Series Service Manual page 163

Sec. 4D
Page 156
PROPELLER SHAFTS
CONDITION
Propeller Shaft Vibration
Universal Joint Noise
at opposite end of propeller shaft are attached to
journal cro ss with snap rings and U-bolts, lock
washers and nuts. A visual inspection must be
made of vehicle to determine at which end of pro­
peller shaft U-bolts and lock rings are used and at
which end of propeller shaft lock rings only are
used. Needle rollers are installed in bearing cages
and oil seals are installed on inner ends of cages.
Repair Kits
Universal joint repair kits are available for
all types of universal joints. Each kit contains a
journal, bearings and seals, and retaining com ­
ponents which should always be replaced when
overhauling a universal joint.
CENTER BEARING (Fig. 2)
Center bearings are used to support center
portion of drive line when two or more propeller
shafts are used. Bearing is ball type, mounted in a
rubber cushion which is attached to frame c r o ss­
member by the center bearing support. The two
center bearings shown in cross section in figure
2 are of the same construction except for shape
and location of dust slinger. View B illustrates
center bearing used at shaft end with slip yoke;
View A illustrates center bearing used at shaft end
with fixed yoke. Bearing is prelubricated and per­
manently sealed. Cavities in grease retainers on
both sides of bearing are packed with waterproof
grease to exclude dirt and water.
LUBRICATION
Journals of universal joints are drilled and
provided with lubrication fittings through which
lubricant travels to all four oil reservoirs, then
through a small hole in side of each reservoir,
direct to needle bearings. Bearings are protected
against lubricant leakage and entrance of foreign
matter by seals. Splines of slip joint are lubricated
through lubrication fitting installed in slip yoke.
G M C S E R V I C E M A N U A L
SERVICE DIAGNOSIS CHART
POSSIBLE CAUSE
1. Propeller Shaft Out of Balance.
2. Parking Brake Drum Out of Balance.
3. Distorted or Damaged Yokes.
4. Yokes Out of Parallel to Each Other.
1. Center Bearing Worn.
2. Worn Universal Joint Bearings.
3. Improper Lubrication.
4. Loose Flange Bolts.
1. Check for Foreign Material
on Propeller Shaft.
2. Replace Drum.
3. Install New Yokes.
4. Change Propeller Shaft.
1. Replace Center Bearing.
2. Replace Bearings.
3. Lubricate as Directed.
4. Tighten to Specifications.
NOTE: Universal joints and slip yoke splines
should be lubricated periodically as specified in
LUBRICATION (SEC. 0) of this manual.
PROPELLER SHAFT REMOVAL
Disconnecting propeller shaft permits removal
of transmission or rear axle without disturbing
unit at opposite end of shaft. On some vehicles,
propeller shaft may be removed at any flange joint
by removing nuts from bolts holding flanges. On
other vehicles, propeller shafts must be discon­
nected at universal joints as described later in this
section. Propeller shaft should be supported oefore
removing to prevent damage by dropping. To re­
move complete drive line, on models in which
center bearings are used, it is necessary to d is­
connect center bearing bracket from hanger and
remove propeller shaft guards (when used) from
supports. Refer to figure 3.
DISASSEMBLY OPERATIONS
SLIP JOINT DISASSEMBLY
With propeller shaft removed, scribe a mark
on slip yoke and shaft to insure assembly is in
exactly same relative position. When clearly mark­
ed, unscrew dust cap and withdraw shaft. Remove
cork washer, steel washer, and dust cap from shaft.
UNIVERSAL JOINT DISASSEMBLY
1. On universal joints using snap rings to re­
tain bearings on journal cross, remove snap rings
(fig. 1).
2. On universal joints using U-bolts to retain
bearings on journal cross, remove nuts and washers
from U-bolts, then remove U-bolts (fig. 1).
3. Strike one side of yoke with hammer to
force one bearing out of yoke. Strike opposite side
of yoke to force opposite bearing out.
CORRECTION