Chrysler RAM TRUCK 2500 1994 Service Manual page 252

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CLUTCH 6 - 19
(a) Mark position of the old gear for alignment
reference on the flywheel. Use a scriber for this
purpose.
(b) Wear protective goggles or approved safety
glasses. Also wear heat resistent gloves when han­
dling a heated ring gear.
(c) Remove the old gear by cutting most of the
way through i t (at one point) with an abrasive cut­
off wheel. Then complete removal with a cold chisel
or punch.
(d) The ring gear is a shrink fit on the flywheel.
This means the gear must be expanded by heating
in order to install it. The method of heating and
expanding the gear is extremely important.
Every surface of the gear must be heated at the
same time to produce uniform expansion. An oven
or similar enclosed heating device must be used.
Temperature required for uniform expansion is
325-350° F.
CAUTION: Never u s e an oxy/acetylene torch to re­
move the old gear, or to heat and expand a new
gear. The high temperature of the torch flame will
cause localized heating and damage the flywheel. In
addition, using the torch to heat a replacement gear
will c a u s e uneven heating and expansion. The torch
flame will also anneal the gear teeth resulting in
rapid wear and damage after installation.
(e) The heated gear must be installed evenly to
avoid misalignment or distortion. A shop press and
suitable press plates should be used to install the
gear i f at all possible.
(f) Be sure to wear eye and hand protection.
Heat resistent gloves and safety goggles are needed
for personal safety. Also use metal tongs, vise grips,
or similar tools to position the gear as necessary
for installation.
(g) Allow the flywheel and ring gear to cool down
before installation. Set the assembly on a work­
bench and let i t cool i n normal shop air.
CAUTION: Do not u s e water, or compressed air to
cool the flywheel. The rapid cooling produced by
water or compressed air can distort, or crack the
gear and flywheel.
CHECKING NV4600 CLUTCH HOUSING RUNOUT
Only the NV4500 clutch housing can be
checked using the following bore and face
runout procedures. The NV3500 clutch housing
is an integral part of the transmission front
case and can only be checked off the vehicle.
MEASURING CLUTCH HOUSING BORE
RUNOUT (NV4S00 ONLY)
(1) Remove the clutch housing and strut.
(2) Remove the clutch cover and disc.
(3) Replace one of the flywheel bolts with an ap­
propriate size threaded rod that is 10 in. (25.4 cm)
long (Fig. 22). The rod will be used to mount the dial
indicator.
(4) Remove the release fork from the clutch hous­
ing.
(5) Reinstall the clutch housing. Tighten the hous­
ing bolts nearest the alignment dowels first.
(6) Mount the dial indicator on the threaded rod
and position the indicator plunger on the surface of
the clutch housing bore (Fig. 23).
(7) Rotate the crankshaft until the indicator
plunger is at the top center of the housing bore. Zero
the indicator at this point.
(8) Rotate the crankshaft and record the indicator
readings at eight points (45° apart) around the bore
(Figs. 22-23). Repeat the measurement at least twice
for accuracy.
(9) Subtract each reading from the one 180° oppo­
site to determine magnitude and direction of runout.
Refer to Figure 24 and following example.
Bore runout example:
0.000 - (-0.007) = 0.007 in.
+0.002 - (-0.010) = 0.012 in.
+0.004 - (-0.005) = 0.009 in.
-0.001 - (+0.001) = -0.002 in. (= 0.002 inch)
I n the above example, the largest difference is
0.012 in. and is called the total indicator reading
(TIR). This means that the housing bore is offset
from the crankshaft centerline by 0.006 in. (which is
1/2 of 0.012 in.).
On gas engines, the acceptable maximum TIR for
housing bore runout is 0.010 inch. I f measured TIR is
more than 0.010 in. (as i n the example), bore runout
will have to be corrected with offset dowels. Offset
dowels are available i n 0.007, 0.014 and 0.021 in.
sizes for this purpose (Fig. 24). Refer to Correcting
Housing Bore Runout for dowel installation.
On diesel engines, the acceptable maximum
T I R for housing bore runout is 0.015 inch. How­
ever, unlike gas engines, offset dowels are not
available to correct runout on diesel engines. I f
bore runout exceeds the stated maximum on a
diesel engine, it may.be necessary to replace ei­
ther the clutch housing, or transmission
adapter plate.
C O R R E C T I N G C L U T C H HOUSING BORE
RUNOUT tN¥4S00 GAS ENGINE ONLY)
On gas engine vehicles, clutch housing bore runout
is corrected with offset dowels. However, i f bore
runout exceeds 0.015 in. TIR on a diesel equipped
model, the clutch housing, or transmission adapter