TRUCK SERVICE MANUAL
TRANSMISSION
HT 700D SERIES TRANSM I S IONS
Para 3-9/3-11
the external lever so that the flat sides of the shaft
3-9. BREATHER
opening are parallel to the flats on the shaft. Install the
nut. While holding the lever against rotation, tighten the
The breather is located at the top of the transmission
nut to 15 to 20 pound feet (21 to 27 Nm) torque.
housing as shown in figure 3-1 The breather serves to
prevent pressure buildup within the transmission. The
(4) Clean and lubricate all hydraulic retarder
breather must be kept clean and the passage open. The
valve linkage. The retarder is applied when the valve
prevalence of dust and dirt will determine the frequency
moves upward (out of the valve body). Therefore, it is
at which the breather requires cleaning. Always use a
important for normal operation with retarder Off, that the
wrench of the proper size to remove or replace the
linkage be adjusted so the valve returns to the retracted
breather. Pliers or a pipe wrench will crush or damage
position. If the linkage causes the retarder to be partially
the stem and produce metal chips which could enter the
applied, loss of lubrication pressure, overheating, or
transmission.
excessive drag will result and fuel consumption will be
excessive. If the valve does not have full travel (1.5 in.
3-10. LINKAGE
[38.1 mm]), maximum performance of the retarder
cannot be obtained.
a. Maintain Proper Adjustment. Proper adjustment
of the manual selector valve linkage is important as the
(5) Inspect the linkage for binding, wear,
shift tower detents must correspond exactly to those in
cracks, breaks and defective cotter pins. Replace all
the transmission. Periodic inspections should be made
defective parts.
for bent or worn parts, loose threaded connections, loose
bolts, and accumulation of grease and dirt. All moving
3-11. SHIFT SPEED ADJUSTMENTS
joints must be kept clean and well lubricated.
b. Reference to Vehicle Manual. Refer to vehicle
NOTE
manual for specific linkage adjustment procedures. The
Transmission shift points cannot be
following general procedures are applicable to most
satisfactorily adjusted if the transmission
vehicles.
has the wrong governor installed.
Check the two-digit code on the head of
(1) The manual selector lever should move
the governor with the code shown in the
easily and give a crisp detent feel in each position. The
current parts catalog (SA 1268) for the
linkage should be adjusted so that the stops in the shift
governor listed for your trans-mission
tower match the detents in the transmission.
assembly part number. If the letter "M"
follows the two-digit code, the governor
(2) When the linkage is correctly adjusted, the
is a service replacement assembly. If
pin which engages the shift lever linkage at the
the "M" is not included, the governor was
transmission can be moved freely in each range.
installed at original factory build.
CAUTION
a. Calibrated On Test Stand Or In Vehicle
Proper installation of the external
selector lever is imperative to the
(1) Proper timing of shift speed points is
function of the transmission. Excessive
necessary for maximum transmission performance.
torque applied to the external selector
Shifts may be adjusted on the test stand when the
lever retaining nut may damage the
transmission is rebuilt or overhauled, or during road
internal selector lever.
testing of the vehicle.
(3) To properly install t h e external lever
(2) Test stand equipment
differs among
proceed as follows. Rotate the manual selector shaft to
rebuild or overhaul facilities. Some shops may have
a position that is two detent notches from either end of its
equipment to drive and load the transmission, with
travel. Install
instrumentation for
702
