Chevrolet 70 1969 Series, Shop Manual

Page: 568 / 913

REAR AXLE 4-13
M E N S IO N (see Step 1 previously), select the proper
adapter disc from the chart. In som e instances, two
identical discs are used, and in other instances two
different slightly tapered discs are used.
9. R etract m icrom eter and install the assembled gauge
in carrier as illustrated in Figure 23.
10. S ubtract from or add to the N O M IN A L A S S E M ­
B LY D IM E N S IO N , the IN D IV ID U A L V A R IA ­
T IO N D IM E N S IO N shown by m arking on pinion
(C, fig. 21). This results in the C O R R E C T E D N O M ­
IN A L D IM E N S IO N .
11. Subtract the thickness (0.400 inch) of the step plate
(m ounted on pinion end), from C O R R E C T E D
N O M IN A L D IM E N S IO N . This results in the C O R ­
R E C T E D M IC R O M E T E R D IS T A N C E .
12. R un m icrom eter thim ble dow n to m easure distance
from center of carrier bores (drive gear center) to step
plate on pinion. This is the IN IT IA L M I C R O M E ­
T E R R E A D IN G (refer to fig. 23).
13. T he difference between the C O R R E C T E D M I­
C R O M E T E R D IS T A N C E and the IN IT IA L M I ­
C R O M E T E R R E A D IN G determ ines the thickness of
shim pack to be removed or added.
a. W hen the "corrected m icrom eter distance" is
m ore than the “ initial m icrom eter reading," shim
pack thickness equal the difference must be added.
As an exam ple:
Refer to left set of gears on Figure 21.
N om inal Assem bly Dimension ..............................
3.551 inches
Individual Variation Distance........................ +0.008 inch
Corrected Nominal Dimension ......................... 3.559 inch
Deduct Step Plate Thickness ............................0.400 inch
Corrected Micrometer Distance ....................... 3.159 inches
Subtract Initial Micrometer Reading ................ 3.139 inches
Shim Pack to be A d d e d .................................0.020
inch
b. W hen the “ corrected m icrom eter distance" is less
than the “ initial m icrom eter reading," shim pack
thickness equal the difference m ust be removed.
As an exam ple:
Refer to right set of gears on Figure 21.
Nominal Assembly Dimension .......................... 2.656 inches
Individual Variation Distance........................ — 0.002
inch
Corrected Nominal Dimension ......................... 2.654 inches
Deduct Step Plate Thickness ............................0.400 inch
Corrected Micrometer Distance ....................... 2.254 inches
Initial Micrometer Reading ............................. 2.274 inches
Subtract 2.254 inches from 2.274 inches equals
The amount of shim pack to be removed 0.020 inch
14. Remove gauge and discs from carrier, also remove
plate.
15. Rem ove pinion and cage assembly as instructed in re­
spective axle assembly.
16. A dd to or remove from original pinion cage to car
rier adjusting shim pack as previously determ ined by
calculations in paragraph 13.
17. Install shim pack pinion and cage assem bly as in­
structed previously under “ Pinion and C age installa­
tion.” Recheck in m anner described above. The " C o r ­
rected M icrom eter R eading” m ust be within plus or
minus 0.002 inch of the “ C orrected N om inal Dis-
Figure 2 3 — Pinion S e ttin g G a u g e Installed
tance.” This will insure properly adjusted tooth con­
tact.
18. Check gear tooth contact by using Red Lead M ethod
as described later in this section. Check gear backlash
as also described later in this publication.
SETTING N E W P IN IO N
(W ITHOUT G A U G E )
W henever a pinion setting gauge is not available, the
approxim ate thickness of the pinion shim pack can be
determ ined as follows:
On those types of axles where the shims are located be­
tween the pinion cage and differential carrier, change
the sign of the m arking (individual variation distance)
on the old pinion (plus to minus or minus to plus),
then add variation of the new pinion (sign unchanged)
which will determ ine how m uch the original shim
Figure 2 4 — C h e c k in g M ic ro m e te r on M a s t e r G a u g e
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SH O P M A N U A L