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PART 7-2- C4 AUTOMATIC TRANSMISSION
7-57
primary throttle
pressure will be
reduced to
Zero
(0),
and reverse and
direct clutch
apply pressure on the
end of the
2-3 back-out valve will
move the valve
down against spring
force.
This
action
immediately con-
nects the clutch
apply circuit to the
intermediate
servo apply circuit,
reducing
the pressure on the apply
side of the servo to
the
same
value
as in the
direct clutch (and also on
the release side
of the
intermediate
servo).
When this happens, the
intermediate
band
is
released, to
provide a smooth
2-3 upshift.
INTERMEDIATE
BAND
ACCUMULATOR
VALVE
TRAIN
The intermediate
band
accumula-
tor valve train is composed
of the
intermediate
band
accumulator
valve,
and the accumulator valve
spring. The intermediate
band
ac-
cumulator valve in conjunction
with
the intermediate servo check valve
controls intermediate servo apply
force on all applications of
the
intermediate
band,
under
open
throttle operating conditions in
D,
2 or I ranges.
Operation
is as follows:
(D
Range: 1-2 Upshifts and
3-2 Downshifts)
(2 and 1 Range: 3-2
Down
shifts-Shifting
D to 2 or 1)
Fluid pressure
from the
02
valve
acting
on
the
apply side of the
inter-
mediate servo
piston tending to
apply
the
servo, causes
the fluid
which is
trapped in the intermediate
servo release
passage to be pres-
surized.
This pressure acting on the
end
of
the
intermediate
servo
accumulator valve will
cause
the
accumulator valve
to move
against
primary T.V. pressure
and/or
the
accumulator valve spring.
The
servo
release
pressure
is exhausted through
the
reverse-direct clutch
apply circuit
to maintain a certain level
of
pressure
on
the release
side of
the
intermediate servo
until it has
completely stroked,
applying
the
band. Force
created
by this pressure
on the release side of
the
servo,
plus
intermediate servo spring force, is
subtracted
from the
force of control
pressure acting on the
apply side of
the
servo,
thereby controlling the
servo
apply
force.
Should
a change
to
2
be made
under closed throttle
conditions,
governor pressure will hold the
cut-
back valve down providing an
exhaust for the intermediate release
circuit
via the
orifice
restriction,
cut-back valve,
2-3
shift valve and
the manual
valve.
(D Range: 2-3 Upshifts)
During a 2-3 upshift, D oil
pressure from the 2-3 shift valve will
unseat the intermediate servo check
valve, bypassing the intermediate
servo accumulator valve, allowing
the release side of the intermediate
servo to be pressurized at the same
pressure level as the direct clutch,
thereby releasing the
intermediate
band.
1-2 TRANSITION VALVE
The 1-2 transition valve prevents
application
of the
intermediate
IN-CAR ADJUSTMENTS AND REPAIRS
CONTROL LINKAGE
ADJUSTMENTS
The transmission
control linkage
adjustments
should be performed in
the
order
in
which they appear
in
this section
of the manual.
THROTTLE ADJUSTMENTS
1. Apply the parking brake, and
place
the selector
lever at N.
2. Run
the
engine at normal idle
speed.
If the engine is cold, run the
engine
at
fast
idle
speed (about 1200
rpm)
until
it
reaches normal operat-
ing temperature.
When the engine
is warm, slow
it
down to normal idle
speed.
3. Connect a tachometer to the
engine.
4. Adjust engine
idle
speed to the
specified rpm with the transmission
selector
lever
at D position.
5. The carburetor throttle lever
must be against the hot idle speed
adjusting screw at the specified idle
speed in D. To make sure that the
carburetor throttle lever is against
the idle adjusting screw, refer to
Group 10 for the carburetor adjust-
ing procedures.
DOWNSHIFT CABLE
ADJUSTMENT
1. With the engine off, check the
accelerator pedal height measured
from the top of the pedal
at
the
pivot point (Fig. 26) to the floor pan.
To obtain the correct pedal height,
adjust the accelerator connecting link
at
point A.
2. With the engine OFF, discon-
nect the downshift control cable
at
point B from the accelerator shaft
lever.
3. With the carburetor choke in
the off position, depress the
accelera-
servo before the release of the
low/
reverse servo during a manual 1-2
upshift.
In 'I' low
/
reverse servo
apply
pressure
is directed to the
spring
end
of the transition valve
forcing the 2-3 backout valve down
against throttle pressure and the
backout
valve spring pressure and
so closing the apply passage to the
intermediate
servo.
When
'2' is selected from 'I
'
apply pressure cannot reach the
intermediate servo until the
low/
reverse servo apply pressure has
been
exhausted at the
02
valve
allowing spring and throttle pres-
sure to move the 2-3 backout valve
and the transition valve up and
open the intermediate servo apply
ports.
THROTTLE PRESSURE
LIMIT
VALVE
The throttle pressure limit valve
is a spring-loaded exhaust valve
used
to prevent possible over pres-
surization in the throttle circuit.
LOW SERVO
MODULATOR
VALVE
The low
servo modulator valve
provides improved engagement of
the
low/
reverse band when manual
'I'
is
selected and during a 3-1
manual
downshift by stabilizing the
low/
reverse servo apply
pressure.
In reverse gear control (line) pres-
sure is applied to the spring end of
the valve from the manual valve.
This ensures that full control pres-
sure
is
applied to the
low/
reverse
servo when reverse gear is selected.
tor
pedal
to the
floor.
Block the
pedal to hold
it in the wide open
position.
4. Rotate
the downshift lever C
counter clockwise
to
place
it against
the internal
stop.
5. With
the lever held in this
position,
and all slack removed
from
the cable, adjust the trunnion
so that
it will slide into the ac-
celerator
shaft lever. Turn it one
additional
turn
clockwise,
then
secure it
to
the lever with the
retaining
clip.
6. Remove
the
block
to release
the accelerator
linkage.
P.EF-C
DOWNSHIFT ROD ADJUSTMENT
1. Disconnect
the throttle
and
downshift return
springs.
2. Hold the
carburettor throttle
lever in
wide-open position against
stop.
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