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21 - SO
AUTOMATIC TRANSMISSION
•
CAUTION: Do not overfill the tranmission. Overfill-
ing may cause leakage out the pump vent which
can be mistaken for a pump seal leak. In addition,
overfilling will also cause fluid aeration and foam-
ing as the excess fluid is picked up and churned by
the gear train. This will reduce the life of the fluid
significantly.
(9) Check fluid condition. F l u i d should be d a r k t o
l i g h t r e d i n color a n d free of d i r t or debris.
(10) I f fluid i s discolored or smells b u r n e d b u t
transmission operation was O K , flush cooler a n d
lines a n d change
fluid
a n d filter. Then road test
again t o c o n f i r m proper operation.
(11) I f fluid is black or d a r k b r o w n , burned/turned
to sludge, contains extensive a m o u n t of metal or fric-
t i o n m a t e r i a l particles, transmission w i l l probably
need o v e r h a u l ; Especially i f problems were evident
d u r i n g road test a n d p r e l i m i n a r y diagnosis.
Effects Of Incorrect Fluid Level
A l o w fluid level allows t h e pump t o take i n a i r
along w i t h t h e fluid. A i r i n t h e fluid w i l l cause
fluid
pressures t o be low a n d develop slower t h a n n o r m a l .
I f t h e transmission is overfilled, t h e gears c h u r n
t h e fluid i n t o foam, a e r a t i n g the fluid and causing
t h e same conditions t h a t occur w i t h a low level.
I n either case, a i r bubbles cause fluid overheating,
oxidation a n d v a r n i s h b u i l d u p w h i c h interferes w i t h
valve,
c l u t c h a n d servo operation. Foaming
also
causes fluid expansion w h i c h can result i n fluid over-
flow
f r o m t h e transmission vent or f i l l tube. F l u i d
overflow can easily be m i s t a k e n for a leak i f inspec-
t i o n is not careful.
THROTTLE VALVE LINKAGE
T h r o t t l e valve l i n k a g e adjustment is i m p o r t a n t to
proper
operation.
T h i s
adjustment
positions t h e
t h r o t t l e valve w h i c h controls shift speed, q u a l i t y and
p a r t t h r o t t l e downshift sensitivity. I f linkage s e t t i n g
is too short, early shifts and slippage between shifts
may occur. I f the s e t t i n g is too long, shifts may be
delayed a n d p a r t t h r o t t l e downshifts m a y be very
sensitive. Refer t o t h e In-Vehicle Service section for
adjustment procedure.
GEARSHIFT LINKAGE
Gearshift l i n k a g e adjustment is i m p o r t a n t because
i t positions the valve body m a n u a l valve. Incorrect
adjustment w i l l cause creeping i n N e u t r a l , prema-
t u r e c l u t c h wear, delayed engagement i n any gear, or
a no-start i n P a r k or N e u t r a l .
Proper operation o f the n e u t r a l switch w i l l provide
a q u i c k check of l i n k a g e adjustment. Refer to the I n -
Vehicle Service section for adjustment procedure.
ROAD TEST
Before road testing, be sure the fluid level a n d a l l
l i n k a g e adjustments have been checked a n d adjusted
i f necessary.
Observe engine performance d u r i n g t h e road test.
A poorly t u n e d engine w i l l n o t allow a n accurate
analysis o f transmission operation.
Operate t h e transmission i n a l l gear ranges. Check
for slippage a n d shift variations. Note w h e t h e r t h e
shifts are h a r s h , spongy, delayed, early, o r i f p a r t
t h r o t t l e downshifts are sensitive.
W a t c h closely for slippage or engine flare w h i c h
u s u a l l y indicates clutch, band or o v e r r u n n i n g c l u t c h
problems. I f t h e condition is advanced, a n o v e r h a u l
m a y be necessary to restore n o r m a l operation.
A s l i p p i n g clutch or band can often be d e t e r m i n e d
by comparing w h i c h i n t e r n a l u n i t s are applied i n t h e
various gear ranges. T h e C l u t c h and B a n d A p p l i c a -
t i o n c h a r t (Fig. 1) provides a basis for a n a l y z i n g r o a d
test results.
Gearshift Lever Position
DRIVE
ELEMENTS
P
R
N
D
2
1
DRIVE
ELEMENTS
P
R
N
1
2
3
1
2
1
FRONT
CLUTCH
•
•
FRONT
BAND
(KICKDOWN)
•
•
R E A R
CLUTCH
REAR
BAND
(LOW-REV.)
•
•
OVER-
RUNNING
CLUTCH
•
•
•
J9021-33
Fig. 1 Clutch And Band Application Chart
ANALYZING THE ROAD TEST
Refer t o t h e C l u t c h and Band A p p l i c a t i o n c h a r t
(Fig. 1) and note w h i c h elements are i n use i n t h e
various gear ranges.
The rear c l u t c h is applied i n a l l forward ranges (D,
2, 1). The o v e r r u n n i n g clutch is applied i n first gear
(D and 2 range only).
The rear band is applied i n 1 and R range only.
For example: I f slippage occurs i n f i r s t gear i n D
a n d 2 range b u t n o t i n 1 range, t h e o v e r r u n n i n g
clutch is slipping. S i m i l a r l y , i f slippage occurs i n a n y
t w o f o r w a r d gears, the rear clutch is slipping.
A p p l y i n g the same method o f analysis, note t h a t
both clutches are applied i n D range t h i r d gear only.
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