Linkage; Shift Selector Lever And Control Linkage; Mechanical Actuator Adjustment; Other Linkage Adjustments - Allison Transmission AT 540 Service Manual

PREVENTIVE MAINTENANCE
EARLIER MODELS
Figure 3–7. Breather Configurations
3–12. LINKAGE
a.

Shift Selector Lever and Control Linkage

CAUTION :
Manual selector shafts that are center drilled at
their outer ends require an M10 x 1.5-6G nut
(metric thread). Shafts that are undrilled require
a 3 ⁄ -16 nut (standard inch series). Use of the
8
wrong nut will damage both the shaft and nut.
Torque for either nut is 15–20 lb ft (20–27 N·m).
(1) To install the shift selector lever and nut,
refer to the latest edition of the AT Mechanic's Tips,
SA1321.
(2) Proper adjustment of the shift selector
control linkage is important as the shift selector de-
tents must correspond exactly to those in the transmis-
sion. Periodic inspections should be made for bent or
worn parts, loose threaded connections, loose bolts,
and accumulation of grease and dirt. All moving joints
must be kept clean and well lubricated. For connecting
and adjusting the shift selector control linkage, refer to
the latest edition of the AT Mechanic's Tips, SA1321.
b. Mechanical Actuator Adjustment. It is im-
perative the mechanical linkage be properly adjusted
for efficient performance. For installing and adjusting
the mechanical modulator control, refer to the latest
edition of the AT Mechanic's Tips, SA1321.
c. Other Linkage Adjustments. For adjust-
ments to other linkage, such as PTO, speedometer,
etc., refer to the latest edition of the AT Mechanic's
Tips, SA1321.
PREVENTIVE MAINTENANCE
NEOPRENE SHROUD
LATER MODELS
V02884
Copyright © 1996 General Motors Corp.
3–13. ADJUSTMENT OF SHIFT POINTS
NOTE:
Transmission shift points cannot be satisfactorily
adjusted if the transmission has the wrong governor
installed. Check the three-digit code on the head of
the governor with the code shown in the Allison
Parts Catalog (SA1235) for the governor listed for
your transmission assembly part number. If the let-
ter "M" follows the three-digit code, the governor is
a service replacement assembly. If the "M" is not in-
cluded, the governor was installed at original factory
build.
a.

Calibrated on Test Stand or in Vehicle

(1) Proper timing of shift speed points is
necessary for maximum transmission performance.
Shifts may be adjusted on the test stand when the
transmission is rebuilt or overhauled, or during road
testing of the vehicle.
(2) The Kent Moore Valve and Governor
Test Stand (J 25000-1) with adapter J 25000-225 or
Aidco (Model 250) is designed to check five principal
transmission functions. It performs a checking proce-
dure on the governor, modulator, hold regulator, shift
points (up-down-inhibit), and a trimmer regulator
check. If a test stand is not available, satisfactory cali-
bration of shift points may be made after road testing
of the vehicle.
b.

Location of Adjusting Components

(1) Shift points are changed by changing the
positions of adjusting rings that determine the retain-
ing force of valve springs in the main control valve
body. Refer to items 4 or 82, and 51, 58, 64, and 70 on
Foldout 11.
(2) Special tool J 24314 is used to depress
and rotate the adjusting rings. Clockwise rotation in-
creases spring force and raises the shift point; counter-
clockwise rotation reduces spring force and lowers the
shift point.
NOTE:
Each notch of adjustment alters the shift point ap-
proximately 40 output shaft rpm or 2 mph (mph
will vary based on axle ratio and tire size).
3–9