or damage. Some technicians will automatically replace
the bearing as a matter of practice. If there is any doubt
about a pilot bearing’s condition, it should be replaced!
Roller- or ball-type pilot bearings should be inspected
for lack of lubrication. To check this, turn the bearing and
feel for roughness. If it does not turn smoothly, it should be
replaced.
In a pilot bushing, wear will show up as looseness
between the bushing and the input shaft pilot. A good way
to check for looseness is to insert a used input shaft into the
bearing and try to wiggle it. If it has too much play, the
bushing is worn out and it should be replaced.
Note:To perform this check, you must have
the same type of input shaft as used in the
vehicle transmission.
Bearing removal
There are a couple ways to remove a pilot bearing.
One way is to use a pilot bearing puller tool, as shown in
Figure 7-21. One variation of this tool is the threaded-tip
puller. The threaded-tip puller is used to remove a pilot
bushing, but it ruins the bearing in the process. The center
shaft, or pilot, of this tool has a self-tapping tip. The pilot is
threaded into the bore of the bearing. When fully inserted,
the legs of the puller are adjusted to seat on the crankshaft
flange. As the tool is tightened further, it pulls the pilot
bearing from the crankshaft bore. Another variation, called
an expandable finger-tip puller, is a similar tool used when
ball or roller bearings are used.
Another way to remove the old pilot bearing is to
pack the recess behind the bearing with heavy grease.
Then, install a driver into the pilot bearing—an old input
shaft works nicely. Put on eye protection and strike the
exposed end of the input shaft with a hammer. The force
from the hammer will travel through the input shaft to the
grease. The grease will push the bearing from the crank-
shaft. See Figure 7-22.
Bearing installation
Before installing the new pilot bearing, slip it over the
pilot of the transmission input shaft. This is done to ensure
it is the proper bearing. If it will not slip over the shaft, or
if the fit is too loose, it is not the correct bearing.
The next step is to drive the new bearing into the
crankshaft bore, Figure 7-23. Use a properly sized driver to
avoid damage. Measure the installed depth of the pilot
bearing. If this depth is too shallow, the input shaft may
contact the bearing. This will damage the bearing, the
input shaft, or both. If the bearing is driven in too deeply,
it may not make full contact with the input shaft pilot. This
is not a problem with bushings, as they are usually longer.
If bushings are driven in too deeply, there is still usually
adequate surface contact with the input shaft pilot.
Once the pilot bearing is properly installed, lubricate
it with a small quantity of high-temperature grease. Most
bearings have a recess behind the bearing. A small amount
of grease stored in this recess will find its way to the bear-
ing surface, helping to keep it supplied with lubricant. See
Figure 7-24.
Chapter 7 Clutch Problems, Troubleshooting, and Service 141
Special puller
Pilot bearing Flywheel
Figure 7-21. The pilot bearing removal tool will make pilot bear-
ing removal easier. (DaimlerChrysler)
Engine
crankshaft
flange
Grease builds
pressure on
rear of pilot
bushing
Heavy grease
packed inside
bore
Old input
shaft
Hammer
blows
Bushing forced
out by grease
Figure 7-22. A pilot bearing can also be removed by packing
grease into the recess behind the bearing. A driver is then
placed into the pilot hole and struck. The driver moves into the
grease, creating pressure.The pressure drives out the bearing.