Copyright © 1996 General Motors Corp. 7–19
ASSEMBLY OF TRANSMISSION
7–13. CHECKING AND ADJUSTING
SHIFT POINTS
Refer to Paragraph 3–13 for shift point checks and ad-
justments.
7–14. POWER TAKEOFF COMPONENTS
(Models Without Retarder)
a. Existing Installation
(1) Unless space limitations prevent, install
the PTO components before the transmission is in-
stalled in the vehicle.
(2) Use the proper shims or gaskets to estab-
lish satisfactory gear backlash 0.006–0.029 inch
(0.15–0.73 mm) or as specified by the PTO manufac-
turer.
b. Determining Turbine-Driven
PTO Backlash
NOTE:
A PTO that whines in operation usually has too lit-
tle backlash (too tight); a clatter indicates too much
backlash (too loose).
(1) Position tool J 34814 (Figure 7–40) onto
PTO pad with plunger engagement between two drive
gear teeth.
(2) Tighten the two hold-down bolts.
(3) Measure the height between the gauge
pin and base plate (Figure 7–40) with a feeler gauge
and refer to the chart.
(4) Install the two headless guide bolts, one
into the top and one into the bottom of the PTO
mounting pad. Place the required shims or gasket on
the guide bolts.
(5) If the PTO has a manual disconnect, be
sure that the disconnect lever is in the disconnect posi-
tion. When the PTO is installed on the mounting pad,
the PTO driven gear must be to the rear of the PTO
drive gear in the transmission.
(6) Install the PTO on the mounting pad.
(7) Connect the lubrication line (if used).
c. New Installation
(1) Contact Allison Transmission Division
of General Motors for approval of planned installation,
or for recommendations.
(2) Speeds, type of duty, power require-
ments, and other factors must be considered when add-
ing a PTO to a transmission. If the job requirements of
the PTO cannot be fully met by the transmission, the
installation will not be satisfactory. Also, the transmis-
sion could be damaged.
(3) Follow all of the recommendations in
Paragraph 7–14a and 7–14b.
(4) If a lubrication source is required, the re-
turn line from-cooler-to-transmission may be tapped.
Provide a 0.032 inch (0.81 mm) restriction in the lubri-
cation circuit (usually already provided in the PTO as-
sembly).
CAUTION:
Cork or other soft gasket material cannot be
used to mount the PTO. Use only the shims or
gaskets recommended by the PTO manufacturer.
CAUTION:
The transmission and PTO can be damaged if
the PTO is installed with its drive gear to the
front of the PTO drive gear.
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