Some flywheel ring gears are welded into position;
others are a shrink fit. If it is determined that the ring gear
is to be replaced, it can be cut from the flywheel with a
cutting torch or a metal saw. Ring gears that are welded are
commonly removed by breaking the welds with a chisel.
Those that are a shrink fit can be heated and then removed
with a chisel. See Figure 7-26A.
Warning: Wear eye protection during ring
gear removal.
If the new ring gear is to be installed by a shrink fit,
you can expand the gear by heating, Figure 7-26B, or
shrink the flywheel by cooling. Usually, the easiest method
is to heat the ring gear with a torch. Try to heat the part
evenly. Once the ring gear is hot enough (close to but not
exceeding 450°F [232°C]), it can be placed over the fly-
wheel, Figure 7-26C.
Caution: Wear welding gloves when han-
dling the hot ring gear or handle it with
tongs.
After the ring gear is placed on the flywheel, it should
be checked for proper seating. Make sure the gear is not
warped; warpage will cause the starter to jam. Once you
have determined that the ring gear is properly installed,
stake it or weld it in place, as necessary.
A cracked, scored, or severely overheated flywheel
must be resurfaced. A severely cracked flywheel must be
replaced. Be sure the replacement flywheel has its balance
weights (thickened areas on flywheel) in the proper posi-
tion. The easiest way to do this is to compare the old and
new flywheels. Therefore, never dispose of the old fly-
wheel until reassembly is complete.
Resurfacing a flywheel is a job for a machine shop.
Generally speaking, any machine shop that can resurface
cylinder heads can resurface a flywheel. The machining
process for flywheels is similar to that for cylinder heads.
Flywheels can be resurfaced by turning on a lathe
(including a brake lathe), cutting on a milling machine, or
grinding on a table with a special grinding wheel. No mat-
ter what method is used, the basic process is the same:
material is removed until the surface is totally clean and
damage-free.
Only a certain amount of metal can be removed,
however. If too much is removed, the flywheel will not
have sufficient metal to absorb heat. Some flywheels are
marked to indicate the maximum amount of metal that can
be removed. If the flywheel is not marked, the machine
shop will usually be able to tell you if there is enough good
metal left in the flywheel. As a general rule, about 0.2″
(5 mm) can be removed from a flywheel that has not been
machined before.
Note: If you placed alignment marks on the
flywheel face, they will be removed during
the machining process. Make a duplicate
mark at the exact spot on the back of the flywheel.
Some flywheels have alignment dowels. These
dowels should be removed before the flywheel is
sent to the machine shop for resurfacing.
Flywheel installation
Once the flywheel is resurfaced, it should be rein-
stalled in its original position. First, reinstall any alignment
dowels. Solid dowels are installed by driving them in
squarely with a soft-faced mallet. A special tool with a
shoulder is needed to drive hollow dowels. Drive the
dowels in carefully until they are fully seated. If there was
a spacer plate between the flywheel and the crankshaft
flange, reinstall it before replacing the flywheel.
Align the crankshaft flange and flywheel bolt holes.
They are usually spaced so they will line up at only one
location. After the bolt holes are aligned, start the flywheel
attaching bolts. Torque the bolts to the proper tension in a
crisscross pattern, Figure 7-27. Use a flywheel holder or a
wood block to hold the flywheel during the tightening
operation.
Caution: Do not tighten the bolts with an
impact wrench. The bolts must be torqued
properly.
Flywheel resurfacing
The flywheel is held to the crankshaft flange with
special hardened bolts. Do not use any other kind of bolt.
Be careful not to accidentally swap the flywheel attaching
bolts with any others.
144 Manual Drive Trains and Axles
5 1
8
4
6
2
7
3
Flywheel holder
Tighten in
crisscross
pattern
Figure 7-27. Torque the flywheel attaching bolts in a crisscross
pattern. Be sure to use the proper bolts and torque them to
specification. Do not use an impact wrench to tighten the bolts.
(Honda)