Copyright by Goodheart-Willcox Co., Inc.
Chapter 15 Transmission and Transaxle In-Vehicle Service 379
Figure 15-23. Special shift kits are available to repair single prob-
lems in a particular transmission. This kit corrects problems
with the torque converter apply on one type of automatic trans-
axle. These kits are a quick and relatively inexpensive way to fix
a unit that has a single problem but otherwise operates well.
Figure 15-24. A—Cover snap ring being removed. Clamp is
then loosened and internal parts are removed. B—This servo is
being removed from its bore.
A
B
Note: Many servos contain internal accu-
mulators or servo pistons that act as
accumulators during certain shifts. For this
reason, accumulator service is often part of servo
service.
to compress the servo return spring so the snap ring can be
removed. Other servo covers are held to the case with
bolts. Some servos are installed under the valve body, and
the valve body must be removed to gain access to these
units. In some designs, a link is used to connect the servo
to the band. To keep the link from falling out of place, turn
the adjusting screw all the way in (bottom the adjuster)
before removing the servo.
To rebuild a servo, begin by removing the servo cover.
To do this, remove the servo cover’s retaining bolts or
depress the servo cover and remove the snap ring. Never
try to remove the snap ring until the cover has been pushed
in and is out of the way. A servo-cover depressor can be
used for this purpose. With the snap ring or bolts out of the
way, remove the servo cover. See Figure 15-24.
Pull the servo apply piston and the return spring from
the servo cylinder. Some servos have more than one piston
and more than one spring. Note the position of the parts as
you remove them. A few pistons will be tight in their cylin-
ders. These can be removed by carefully applying air pres-
sure to the servo release port. See Figure 15-25. The valve
body must be removed for this operation.
Remove the seals from the servo piston(s), noting the
direction that the sealing lips on the lip seals face, if used. See
Figure 15-26. Check the servo piston and piston pin for wear.
Normally, servo parts do not wear very much. If a spring
height measurement is given in the service manual, check
the spring with a sliding caliper as shown in Figure 15-27.
If the spring is not within specifications, replace it.
After cleaning all servo parts, select, lubricate, and
install the new seals on the servo apply piston. Some servos
have multiple pistons, and all seals should be replaced.
There may be a seal on the servo apply piston pin. This seal
should also be replaced.
Install the servo piston(s) in the cylinder. Make sure all
servo pistons and springs are reinstalled in their original
locations. Select the proper servo cover O-rings or gasket,
and reinstall the servo cover.
Accumulator Service