used, the piston can be pressed or tapped into the bore
after being thoroughly lubricated.
A piston using a lip seal must be worked into place
with a feeler gauge or a special seal installation tool. A
satisfactory tool can be made from a stiff piece of wire and
a small length of copper tubing. Use the tool to push in
the seal as you press on the piston. See Figure 17-24.
Once the piston is in place, check its installation by trying
to turn it. If you cannot turn the piston, the seal is not
properly positioned.
Once you are sure the piston is properly installed, put
the piston return spring(s) and spring retainer back in posi-
tion on the piston. Then, use the spring compressor tool to
move the return spring(s) and retainer past the groove for
the retaining snap ring. Install the snap ring, and make sure
it is snug in its groove. See Figure 17-25.
If the clutch pack uses a reaction plate next to the
apply piston, install it now. Then install the friction discs
and steel plates, alternating them and using new parts as
required. Always use new friction discs. Some technicians
reuse the steel plates after buffing the plates to remove the
shiny surface. Some friction disc manufacturers recom-
mend that if reused, the old steel plates be installed without
buffing. These manufacturers state that buffing the steel
plates causes rapid wear of the new friction discs. It is often
quicker, and therefore cheaper, to install new steel plates.
If the clutch pack uses a reaction plate at the top,
install it before installing the outer snap ring.
With the clutch pack now assembled, measure the
clutch clearance, or the distance between the pressure
plate and outer snap ring. Clutch clearance is checked
with a feeler gauge, Figure 17-26. The exact placement
of the feeler gauge will vary between makes. Most
410 Automatic Transmissions and Transaxles
Seals, direct
clutch piston
Seal tool
Press lightly on piston as you
work the lip seal downward
Housing and
drum assembly,
direct clutch
Snap ring
pliers
Clutch spring
compressor
Retaining
ring
Figure 17-25. To reassemble the apply piston and return spring
assembly, depress the return springs below the snap ring
groove and install the snap ring. Sometimes it is easier to install
the snap ring by hand or with a small screwdriver than it is to
install it using the snap ring pliers. (Ford)
Figure 17-24. This special tool can be fabricated from copper
tubing and wire to make lip seal installation easier.This tool will
be much less likely than a feeler gauge to cut the new seal.
(General Motors)
Caution: A dry friction disc will burn
severely the first time the clutch is applied.
To prevent this, soak new friction discs in
clean transmission fluid before installing them. Allow
them to soak for about 15 minutes or until they stop
bubbling. Always use the correct type of automatic
transmission fluid. The vehicle owner’s manual
should list the proper ATF.The fluid type may also be
stamped on the transmission dipstick.
Figure 17-26. One of the most critical parts of transmission
rebuilding is checking the clutch pack clearance. Incorrect
clearances must be fixed by replacing the pressure plate or
snap ring with one of the proper thickness.