Chevrolet 70 1969 Series, Shop Manual

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TANDEM REAR AXLE
REAR AXLE 4-31
(E A T O N T A N D E M 30DS A N D 34DS)
This section includes description and overhaul inform a­
tion on Eaton T andem single reduction (M odel DS) rear
axles used on models as indicated in M O D E L D A T A at
front of this M anual.
Refer to “ Specifications” at end of this section for new
limits, fits, tolerances, torque readings, available shim
thicknesses and other im portant inspection and reassem ­
bly inform ation.
DESCRIPTIO N A N D O P E R A T IO N
R ear axle unit consists of two spiral bevel type rear
axle assemblies. Forw ard unit (fig. 1) incorporates an
inter-axle differential and thru-shaft, in addition to a con­
ventional type differential. Inter-axle differential allows
the two axles to operate independently of each other or to
be locked together as a single unit. The thru-shaft perm its
power to be transm itted from input shaft through inter­
axle differential and output shaft to inter-axle propeller
shaft.
PINION AND SHAFT
The spiral bevel drive pinion on forw ard and rearw ard
rear axle units is straddle m ounted with two tapered roller
bearings at front and one straight roller bearing at rear.
Pinion on front unit is driven by inter-axle differential
forw ard side gear.
INTER-AXLE DIFFERENTIAL (FORWARD AXLE)
The function of the inter-axle differential is to divide
the torque between the tw o axles in the sam e m anner as
the differential in a single axle divides the torque between
two wheels.
Action of the inter-axle is controlled by the driver
through a shift cham ber attached to side of inter-axle dif­
ferential cover.
W hen inter-axle differential is locked by sliding clutch
gear, the front and rear axles operate as one unit. This is
desirable in event one of the axles encounters loss of trac­
tion.
Inter-axle differential front side gear drives forward
axle while rear side gear drives rearw ard axle.
DIFFERENTIAL ASSEMBLY
Differential in each axle is conventional four pinion
type with drive gear bolted to flanged half of differential
case. The two halves of differential case are m achined as
an assembly and m ust be replaced as such.
T hrust washers are used between pinions and case, also
between side gears and case. T hrust washers m ust be re­
placed in sets.
Com plete differential assem bly is supported by opposed
tapered roller bearings located in legs of carrier. Bearings
are adjustable to provide proper drive gear location and to
adjust bearing pre-load.
AXLE SHAFTS
Axle shafts are full floating type, splined to differential
side gears at inner end, and attached to hubs by studs and
nuts at flanged end. Stud holes in flange are taper-ream ed
to accom m odate split tapered dowels.
O V ER H A U L
R ear axle assemblies should be completely removed
from vehicle whenever differential carrier assem bly is to
be disassem bled for overhaul. However, axle shafts can be
replaced w ithout removing axle assembly.
Except for construction of pinion shafts and inter-axle
differential on front unit, front and rear differential units
are the same. Following procedures describe front units
and apply to both front and rear units unless otherwise
noted in text.
Before and during axle disassem bly check the fol­
lowing:
1. C heck axle housing for lubricant leaks before clean­
ing, then steam clean thoroughly.
2. C heck pinion and bevel gear backlash. Refer to
“ Specifications” at end of this section.
3. C heck pinion gear shaft, also differential bearing end
play. This inform ation should be recorded at tim e of
disassembly for reference at time of reassembly.
REMOVE HOUSING COVER (FWD. AXLE)
D ISA SSEM B LY
1. Rem ove yoke nut and washer, then rem ove yoke (16)
using suitable puller. Rem ove bearing retaining wash-
R E F E R E N C E N U M B E R S IN D IS A S S E M B L Y P R O - er.
C E D U R E S F O L L O W IN G R E F E R T O F I G U R E 1. 2. Rem ove cap screws, stud nuts, and lock washers at-
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SHO P M A N U A L