GMC 1982 Light Duty Truck, Service Manual

Page: 518 / 1435

4C-12 FRONT AXLE
satisfactory pattern. Turn companion flange with
wrench so that ring gear rotates one full revolution then
reverse rotation so that ring gear rotates one revolution
in opposite direction. Excessive turning of ring gear is
not recommended.
5. Observe pattern on ring gear teeth and compare with
Figure 4C-16.
A d ju stm e n ts A ffe c tin g Tooth C o n ta ct
Two adjustments can be made which will affect tooth
contact pattern. These are backlash and position of drive
pinion in carrier. The effects of bearing preloads are not
readily apparent on hand loaded teeth pattern tests:
however, these adjustments should be within specifications
before proceeding with backlash and drive pinion
adjustments.
It may be necessary to adjust both pinion depth and
backlash to obtain the correct pattern.
The position of the drive pinion is adjusted by
increasing or decreasing the shim thickness between the
pinion head and inner race of rear bearing. The shim is used
in the differential to com pensate for m anufacturing
tolerences. Increasing shim thickness will move the pinion
closer to centerline of the ring gear. D ecreasing shim
thickness will move pinion farther away from centerline of
the ring gear.
Backlash is adjusted by means of the side bearing
adjusting shims which moves the entire case and ring gear
assembly closer to, or farther from the drive pinion. (The
adjusting shims are also used to set side bearing preload). To
increase, backlash, increase right shim and decrease left
shim an equal amount. To decrease backlash decrease right
shim and increase left shim an equal amount.
The important thing to note is that the contact pattern
is centrally located up and down on the face of the ring gear
teeth.
SPECIFICATIONS
C H E V R O L E T
A x le
B o lt T o rq u e s
(F t.-Lbs.)
A x le
B o lt T o rq u e s
(F t.-Lb s.)
G e a r a n d B a c k la s h P re fe rre d
.0 0 5 -.0 0 8 C a r r ie r C o v e r
20
M in . a n d M a x . .0 0 3 -.0 1 0
R in g G e a r
80
N e w P in io n B e a r i n g P r e lo a d 1 5 -3 0 in .-lb s .
D if fe r e n t ia l B e a r i n g C a p s
55
U s e d P in io n B e a r i n g P r e lo a d 5 -1 0 in .-lb s .
F ille r P lu g s
25
D A N A
Axle
B o lt T o rq u e s
(F t.-Lbs.)
A x le
Bolt Torques
(Ft.-Lbs.)
G e a r Backlash Preferred .004"-. 0 0 9 " C arrier Cover
35
M in. a n d M ax .
.0 0 4 "-.0 0 9 " Ring G e a r * — K-30
110
New Pinion B e a rin g Preload
20-40 in.-lbs. Differential B e a rin g C a p s
85
Used Pinion B e a rin g Preload
10-20 in.-lbs. Filler Plugs
10
Drive Pinion N u t * * — K-30
270
Specification Chart 4C-1