Ford COUGAR 1968 Shop Manual page 195

PART 7-1
-
General Trorlsmission Service
vehicle coasting at a speed above 55 formed to determine the exact cause
SHIFT POINT CHECKS
MPH, the selector leier should be
moved to the 1 position; if the coast-
ing boost valve is operating properly,
an increase in line pressure will be
noted. As speed drops below approxi-
mately 55 M P H , a drop in line pres-
sure should be noted, indicating that
the boost valve and governor are op-
erating properly. If line pressure does
not respond as described, either the
governor or the coasting boost valve
is at fault. If shift points indicate
that the governor is operating cor-
rectly and other control pressures
check out to specification then the
problem is due to a sticking or inop-
erating coating boost valve.
STALL TEST
Start the engine to allow it to
reach its normal temperature. Apply
both the parking and service brakes
while making tests.
The stall test is made in D, 2,
1
or
R, at full throttle to check engine per-
formance, converter clytch operation
or installation, and.the holding abil-
ity of the forward clutch, reverse-high
clutch and low-reverse band and the
gear train one-way clutch.
While
making this test, do not hold the throt-
tle open for more than five seconds at
a time. Then move the .selector lever to
Neutral and run engine a t 1000
rpm for about 15 seconds to cool the
converter before making the next test.
If the engine speed recorded by the
tachometer exceeds the maximum
limits shown in Figure 12, release the
accelerator immediately because clutch
or band slippage is indicated.
S T A L L S P E E D T O O
HIGH
If stall speed exceeds specifica-
tions, band or clutch slippage is in-
dicated, depending on transmission
selector lever position. Excessive en-
gine rpm only in D, 2 and I indi-
cates forward clutch slippage. Exces-
sive engine rpm only in R indicates
either reverse-high clutch or low-
reverse band slippage in the C 4
transmission, and either reverse-high
or low-reverse slippage in the C 6
transmission. Excessive engine rpm
only in D indicates gear train one-
way clutch slippage.
S T A L L S P E E D T O O L O W
When the stall test speeds are low
and the engine is properly tuned,
converter stator clutch problems are
indicated. A road test must be per-
of the trouble.
I f the stall test speeds are 300 to
400 rpm below the specifications
shown in Figure 12, and the vehicle
cruises properly but has very poor
acceleration, the converter stator clutch
is slipping.
If the stall test speeds are 300 to
400 prm below the specified values,
and the car drags at cruising speeds
and acceleration is poor, the stator
clutch could be installed backwards.
Remove the converter and check
the stator clutch as described in
Cleaning and Inspection.
When the stall test shows normal
speeds, the acceleration is good, but
the car drags at cruising speeds, the
difficulty is due to a seized stator
assembly. If the stator is defective,
replace the converter.
INITIAL ENGAGEMENT
CHECKS
Initial engagement checks are
made to determine if initial band
and clutch engagements are smooth.
Run the engine until its normal
operating temperature is reached.
With the engine at the correct idle
speed, shift the selector lever from
N to 2, D, I and R. Observe the
initial band and clutch engagements.
Band and clutch engagements should
be smooth in all positions. Rough
initial engagements in D, 2, I, or R
are caused by high engine idle speed
or high control pressures.
Engine Engine Trans-
M o d e l Speed mission
CID
( r ~ m ) Type
170-1V 1400-1600 C 4
200- 1V 1500-1700 C4
289-2V 1700-1940 C 4
302-2V,4V 1780-2000 C 4
390-2V 1680-1900
0
C6
390-2V 1720-1940
@
C 6
390-4V GT
1750-1980 C 6
@
Regular Fuel
@
Premium FueI
FIG. 12-Stall
Speed Limits
Check the light throttle upshifts in
D. The transmission should start in
first gear, shift to second, and then
shift to third within the shift points
specified in the specifications section.
While the transmission is in third
gear, depress the accelerator pedal
through the detent (to the floor). The
transmission should shift from third
to second or third to first, depending
on the vehicle speed.
Check the closed throttle down-
shift from third to first by coasting
down from about 30 mph in third
gear. The shift should occur within
the limits specified in the specifica-
tions section.
When the selector lever is at 2,
the transmission can operate only in
second gear.
With the transmission in third gear
and road speed over 30 mph, the
transmission should shift to second
gear when the selector lever is moved
from D to 2 to I . The transmission
will downshift from second or third to
first gear when this same manual
shift is made below approximately
25 mph with a C 4 transmission or
approximately 30 mph with a C 6
transmission.
This check will determine.
if the governor pressure and shift
control valves are functioning properly.
Dur~ng the shift check operation,
if the transmission does not shift
within specifications or certain gear
ranges cannot be obtained, refer to
the Diagnosis Guide to resolve the
problem.
AIR PRESSURE CHECKS
A N O DRIVE condition can
exist, even with correct transmission
fluid pressure, because of inoperative
clutches, bands. The inoperative
units can be located through a series
of checks by substituting air pressure
for the fluid pressure to determine
the location of the malfunction.
When the selector lever is a t 2, a
N O DRIVE condition may be caus-
ed by an inoperative forward clutch.
A N O DRIVE condition a t D may
be caused by an inoperative for-
ward clutch or one-way clutch.
When there is no drive in I, the
difficulty wuld be caused by im-
proper functioning of the forward
clutch or low-reverse band and the
one-way clutch in a C4, or the for-
ward clutch or low-reverse and one-
way clutches in the C 6 transmission.
The low-reverse band in the C4
transmission and low-reverse in the
C 6 transmission cannot be checked
in I. If the low-reverse band or