repeat this procedure at least three more times at different
positions on the flywheel. If any of the samples produce
fluctuations exceeding 0.01″ (0.25 mm), the flywheel must
be resurfaced.
As mentioned, the surface of the flywheel should also
be checked for runout. This is a condition of a rotating
object, such as a shaft or flywheel, in which the surface is
not rotating in a true circle or plane. Radial runout is a
measure of out-of-roundness. It is measured at right angles
to the centerline of an object. Excessive radial runout may
be caused, for example, by a bent shaft. Lateral runout is
a measure of in-and-out movement, or wobble. It is mea-
sured in the direction that is lengthwise to the centerline of
the rotating object. In other words, it is measured on the
plane surface of the rotating object. Excessive lateral
runout can result, for example, if a flywheel is not mounted
properly.
To check for lateral runout, slowly rotate the flywheel
while watching the dial indicator. Determine the lowest
point on the flywheel, which corresponds to the lowest
reading on the dial. Zero the indicator at this point. Move
the flywheel until the highest reading is recorded. This
measurement is the lateral runout.
Lateral runout should not exceed the manufacturer’s
specifications. If it does, the flywheel may not be mounted
properly. Remove it and check for burrs between the fly-
wheel and the face of the crankshaft flange. If no burrs
exist, check the runout of the crankshaft flange.
Note that while the dial indicator is mounted, you can
also measure crankshaft endplay. Push the flywheel for-
ward and rearward and note the displacement on the dial.
Flywheel removal
The easiest way to remove the flywheel attaching
bolts is with an impact wrench. If you do not have an
impact wrench to remove the flywheel, it must be kept
from rotating so the attaching bolts can be loosened. While
the bolts are being removed, the flywheel can be held in
place using a flywheel turner or locked in place with a fly-
wheel holder; alternatively, a block of wood can be placed
between the flywheel and a stationary part of the engine.
Warning: Always wear eye protection when
using an impact wrench.
A flywheel is very heavy. It can cause injury or severe
damage if dropped. Do not remove the bolts completely
until you have the flywheel secured so that it cannot fall.
Once the flywheel is securely held, the bolts can be
loosened and the flywheel can be removed. Sometimes there
is a flat metal spacer between the flywheel and the crankshaft
flange. The spacer should be saved for reassembly.
After removing the flywheel, check the rear main
bearing seal for leaks. If the seal is leaking, oil could reach
the new clutch disc and ruin it, just as it may have ruined
the old disc. A leaking seal must be replaced.
Flywheel repair
Some flywheels may be damaged beyond repair.
Others may be repaired and then reinstalled. Some of
these may be fixed by replacing the ring gear or by
resurfacing.
Flywheels with damaged ring gears are usually
replaced. Some ring gears can be removed from the fly-
wheel and replaced, Figure 7-26.
Chapter 7 Clutch Problems, Troubleshooting, and Service 143
Flywheel
Use chisel to
split and remove
ring gear
Torch
Heat new ring
gear to expand and
ease installation
A
B
C
Figure 7-26. Most manual transmission flywheels have a
removable ring gear. A—A chisel is being used to remove the
ring gear from a flywheel. Be careful not to damage the
flywheel. B—You should heat the replacement ring gear with a
torch or in an oven. Be careful not to overheat the ring gear, or
the metal will lose its strength. C—Place the new ring gear over
the flywheel and ensure that it is properly seated. Always wear
gloves or use tongs to prevent burning your hands when
handling the hot ring gear. (General Motors)