Chrysler Dodge Caravan 2002 Manual page 1668

RS
SERVO - KICKDOWN
DESCRIPTION
The kickdown servo (Fig. 196) consists of a two-
land piston with an inner piston, a piston rod and
guide, and a return spring. The dual-land piston uses
seal rings on its outer diameters and an O-ring for
the inner piston.
Fig. 196 Front Servo
1 - VENT
2 -PISTON ROD
3 - PISTON
4 - SPRING
5 - RELEASE PRESSURE
6 - APPLY PRESSURE
OPERATION
The application of the piston is accomplished by
applying pressure between the two lands of the pis-
ton. The pressure acts against the larger lower land
to push the piston downward, allowing the piston rod
to extend though its guide against the apply lever.
Release of the servo at the 2-3 upshift is accom-
plished by a combination of spring and line pressure,
acting on the bottom of the larger land of the piston.
The small piston is used to cushion the application of
the band by bleeding oil through a small orifice in
the larger piston. The release timing of the kickdown
servo is very important to obtain a smooth but firm
shift. The release has to be very quick, just as the
front clutch application is taking place. Otherwise,
engine runaway or a shift hesitation will occur. To
accomplish this, the band retains its holding capacity
until the front clutch is applied, giving a small
amount of overlap between them.
31TH AUTOMATIC TRANSAXLE
DISASSEMBLY
(1) Remove kickdown servo snap ring (Fig. 197).
Fig. 197 Kickdown Servo Snap Ring
1 - SNAP RING
2 - SNAP RING PLIERS
3 - ACCUMULATOR PLATE
4 - KICKDOWN LEVER
5 - KICKDOWN PISTON ROD GUIDE
(2) Remove kickdown servo rod guide and snap
ring (Fig. 198).
Fig. 198 Kickdown Servo Rod Guide and Snap Ring
1 - SNAP RING
2 - ACCUMULATOR PLATE
3 - RETURN SPRING
4 - O-RING
5 - PISTON ROD GUIDE
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