Front Servo; Description; Operation - Dodge Dakota Sport 2001 Service Manual

AN
FRONT CLUTCH (Continued)
(6) Position spring retainer on top of piston spring.
Make sure retainer is properly installed (Fig. 86).
Fig. 90 Front Clutch Piston Installation
1 - CLUTCH PISTON
2 - FRONT CLUTCH RETAINER
Fig. 91 Clutch Piston Spring Installation
1 - RETAINER
2 - CLUTCH SPRING
3 - PISTON
(7) Compress piston spring and retainer with Com-
pressor Tool C-3575-A (Fig. 87). Then install new
snap-ring to secure spring retainer and spring.
(8) Install clutch plates and discs (Fig. 86). Install
steel plate then disc until all plates and discs are
installed. The front clutch uses 4 clutch discs and
plates in a 42RE transmission.
(9) Install pressure plate and waved snap-ring
(Fig. 86).
Clearance should be 1.70 to 3.40 mm (0.067 to
0.134 in.). If clearance is incorrect, clutch discs,
plates, pressure plates and snap-ring may have to be
changed.
AUTOMATIC TRANSMISSION - 42RE

FRONT SERVO

DESCRIPTION

The kickdown servo (Fig. 92) 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. 92 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.
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