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AUTOMATIC TRANSMISSION
21 - 47
RECOMMENDED FLUID
Recommended
fluid
for a l l Chrysler
automatic
transmissions i s Mopar A T F Plus, Type 7176, or Mo-
par D e x r o n II™.
Mercon™ transmission fluid should only be used for
topping off the transmission fluid level d u r i n g a nor-
m a l maintenance check. I t i s not recommended for
r e f i l l i n g after scheduled maintenance o r after over-
h a u l .
TRANSMISSION IDENTIFICATION
The transmission part/identification numbers are
stamped on the left side of the case j u s t above the oil
pan gasket surface. Refer t o t h i s i n f o r m a t i o n when
ordering replacement parts for any Loadflite trans-
mission.
TRANSMISSION CONTROLS AND COMPONENTS
The transmission h y d r a u l i c control system provides
f u l l y automatic operation. T h e system performs
five
basic functions, w h i c h are: pressure supply, pressure
r e g u l a t i o n , flow control, clutch/band application, and
l u b r i c a t i o n .
Pressure Supply
The o i l p u m p develops fluid pressure for clutch/
band application and for lubrication. T h e pump is
d r i v e n b y the torque converter w h i c h is attached to
the engine crankshaft b y the driveplate.
Pressure Regulation
The pressure regulator valve maintains transmis-
sion l i n e pressure. The amount o f pressure developed
is controlled b y t h r o t t l e pressure w h i c h is dependent
on t h e degree o f t h r o t t l e opening. T h e regulator
valve i s located i n t h e valve body. T h e governor
valve i s operated b y the transmission o u t p u t shaft.
The t h r o t t l e valve determines line pressure and
shift speed. Governor pressure increases i n propor-
t i o n t o vehicle speed.
The t h r o t t l e valve also controls upshift and down-
shift speeds b y r e g u l a t i n g pressure i n conjunction
w i t h t h r o t t l e position.
Flow Control And Lubrication
The m a n u a l valve is operated by the gearshift l i n k -
age a n d provides the operating range selected by the
driver.
The 1-2 shift valve provides automatic 1-2 or 2-1
shifts a n d the 2-3 shift valve provides automatic 2-3
or 3-2 shifts. The k i c k d o w n valve provides forced 3-2
or 3-1 downshifts depending on vehicle speed. Down-
shifts occur w h e n t h e t h r o t t l e is opened
beyond
downshift detent position w h i c h is j u s t before wide
open t h r o t t l e .
The 2-3 valve t h r o t t l e pressure p l u g provides 3-2
downshifts w i t h v a r y i n g t h r o t t l e openings a n d de-
pending on vehicle speed. The 1-2 shift control valve
t r a n s m i t s 1-2 s h i f t pressure t o the accumulator pis-
t o n to control k i c k d o w n band capacity on 1-2 upshifts
a n d 3-2 downshifts.
The
l i m i t valve determines
m a x i m u m speed a t
w h i c h a 3-2 p a r t t h r o t t l e k i c k d o w n can be made.
Some transmissions do n o t have the l i m i t v a l v e and
m a x i m u m speed for a 3-2 k i c k d o w n is a t t h e detent
position.
The shuttle valve has two functions. F i r s t i s fast
front
band release and smooth engagement d i n i n g
lift-foot 2-3 upshifts. The second is t o regulate
front
c l u t c h and band application d u r i n g 3-2 downshifts.
The lockup valve automatically applies t h e con-
verter lockup c l u t c h w h e n supplied w i t h l i n e pres-
sure t h r o u g h t h e lockup solenoid. The solenoid i s
controlled b y the engine electronics t h r o u g h a n elec-
t r i c a l connector a t the rear of the transmission case.
Electronic control o f torque converter lockup i n -
cludes converter u n l o c k i n g a t closed t h r o t t l e d u r i n g
w a r m u p and d u r i n g p a r t t h r o t t l e acceleration. T h e
non-lockup A-998 used i n California has a threaded
p l u g i n the rear o f t h e transmission case i n place o f
t h e lockup w i r i n g connector.
The f a i l safe v a l v e restricts feed t o the
converter
lockup clutch i f f r o n t clutch pressure drops. I t per-
m i t s lockup only i n direct (third) gear and provides
fast lockup release d u r i n g a kickdown.
The switch valve directs apply fluid pressure to the
lockup clutch i n one position and releases i t i n the
opposite position. I t also directs o i l to the cooling and
lube circuits. The switch valve regulates o i l pressure
to t h e torque converter b y l i m i t i n g m a x i m u m o i l
pressure to 130 psi.
Clutch/Band Application
The front/rear c l u t c h pistons and servo pistons are
actuated b y l i n e pressure. When line pressure is r e -
moved, the pistons are released b y spring tension.
O n 2-3 upshifts, the front servo piston i s released
by s p r i n g tension and hydraulic pressure. T h e accu-
m u l a t o r controls h y d r a u l i c pressure on the apply side
of the front servo d u r i n g 1-2 upshifts a t a l l t h r o t t l e
openings.
Gearshift And Parking Lock Controls
The
gearshift
lever provides
six operating
posi-
tions: P a r k (P), Reverse (R), N e u t r a l (N), a n d t h e D ,
2 and 1 forward drive ranges.
1
position provides
overrun b r a k i n g w h e n t h e
t h r o t t l e is released. However, upshifts are not pro-
vided i n 1 position. 1-2 up shifts w i l l occur i n 2 posi-
t i o n b u t no 2-3 upshift w i l l take place. D position
provides 1-2, 2-3 upshifts and 3-2 and 3-1 downshifts.
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