bore and that the bore is round. The ring should touch the
bore all the way around.
Parts having worn or damaged seal ring grooves or
bores should be replaced. Always install new seal rings
carefully, using plenty of transmission fluid as a lubricant.
Bearing and Thrust Washer Service
All transmission bearings and thrust washers should
be checked for wear and scoring. A badly worn thrust
washer is shown in Figure 17-39. This washer should be
replaced. General procedures for checking bushings and
washers were discussed in Chapter 4. Figure 17-40A
shows the procedure for checking bushing wear in a sun
gear. Figures 17-40B and 17-40C show the procedure used
to replace a bushing. Note the use of special tools to
remove the old bushing and install the new one.
There are many thrust washers in modern automatic
transmissions and transaxles. Some of these thrust washers
are made in selective thicknesses to control endplay. All
thrust washers should be checked with a micrometer to
ensure proper endplay. Use thicker or thinner washers as
needed. For instance, if the endplay is 0.030″ (0.762mm)
too large, a 0.030″ thicker thrust washer should be
obtained. If endplay is insufficient, a thinner selective
thickness washer should be used. Always recheck endplay
to confirm that the proper washer was selected.
Miscellaneous Case Parts Service
Many small parts are installed in the case, including
electrical switches and sensors, electrical case connectors,
small screens in the pump output passages, seals, and
check balls. These parts are as important as the major
transmission components. They must be cleaned and care-
fully checked for wear and damage. Electrical parts should
be checked according to the manufacturer’s instructions,
using the proper electrical test equipment. Seals, such as
those used on the T.V. cable or the manual lever and shaft
assembly, should always be replaced.
Reassembly
Once all automatic transmission or transaxle
subassemblies have been rebuilt, they can be installed in
the transmission case. Always refer to the manufacturer’s
service manual for the exact assembly procedures. It will
give procedures and specifications for the type of trans-
mission or transaxle being serviced. Exploded views are
very useful during the reassembly process.
Chapter 17 Rebuilding Automatic Transmissions and Transaxles 415
Inspect
all gears
Check bearing or
bushing contact
surface for wear
Grooves for
seal rings must be
in good condition
Oil feed holes
should be cleaned out
Inspect each roller of
tapered roller bearing
Figure 17-37. If any of the shafts contain seal ring grooves, the
grooves should be closely inspected for wear.
Seal ring
Feeler gauge
Shaft
Ring groove
Figure 17-39. This thrust washer is badly worn and should be
replaced. If you encounter a thrust washer showing this degree of
wear, remember to inspect the part the washer rides against.
Chances are good that the riding surface of the part is also worn out.
Figure 17-38. Seal rings and grooves are vital to proper
operation of the transmission or transaxle hydraulic system.
They should be carefully checked to ensure that they can do a
good job of sealing. Using a feeler gauge as shown here, the
maximum end clearance of a new seal ring in its groove should
be about 0.003″–0.006″ (0.07mm–0.14mm).
Note: Remember to soak the friction discs,
bands, and all rubber parts in fresh trans-
mission fluid before installation.