NV4500 Clutch Housing
CHECKING RUNOUTOnly the NV4500 clutch housing can be checked using the following bore and face runout procedures. The NV3500 and NV5600 clutch housings are an integral part of the transmission and can only be checked off the vehicle.
MEASURING CLUTCH HOUSING BORE RUNOUT
1. Remove the clutch housing and strut.
2. Remove the clutch cover and disc.
Fig. 15:
3. Replace one of the flywheel bolts with an appropriate size threaded rod that is 10 inch (25.4 cm) long (Fig. 15). The rod will be used to mount the dial indicator.
4. Remove the release fork from the clutch housing.
5. Reinstall the clutch housing. Tighten the housing bolts nearest the alignment dowels first.
Fig. 16:
6. Mount the dial indicator on the threaded rod and position the indicator plunger on the surface of the clutch housing bore (Fig. 16).
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 (Fig. 16). Repeat the measurement at least twice for accuracy.
Fig. 17:
9. Subtract each reading from the one 180° opposite to determine magnitude and direction of runout. Refer to (Fig. 17) and following example.
Bore runout example:
0.000 - (-0.007) = 0.007 inch
+0.002 - (-0.010) = 0.012 inch
+0.004 - (-0.005) = 0.009 inch
-0.001 - (+0.001) = -0.002 inch (= 0.002 inch)
In the above example, the largest difference is 0.012 inch and is called the Total Indicator Reading (TIR). This means that the housing bore is offset from the crankshaft centerline by 0.006 inch (which is 1/2 of 0.012 inch).
On gas engines, the acceptable maximum TIR for housing bore runout is 0.010 inch. If measured TIR is more than 0.010 inch (as in the example), bore runout will have to be corrected with offset dowels. Offset dowels are available in 0.007, 0.014 and 0.021 inch sizes for this purpose (Fig. 17). Refer to Correcting Housing Bore Runout for dowel installation.
On diesel engines, the acceptable maximum TIR for housing bore runout is 0.015 inch. However, unlike gas engines, offset dowels are not available to correct runout on diesel engines. If bore runout exceeds the stated maximum on a diesel engine, it may be necessary to replace either the clutch housing, or transmission adapter plate.
Correcting Clutch Housing Bore Runout- Engine Only
On gas engine vehicles, clutch housing bore runout can be corrected with offset dowels.
The dial indicator reads positive when the plunger moves inward (toward indicator) and negative when it moves outward (away from indicator). As a result, the lowest or most negative reading determines the direction of housing bore offset (runout).
Fig. 18:
In the sample readings shown (Fig. 18) and in Step 7 above, the bore is offset toward the 0.010 inch reading. To correct this, remove the housing and original dowels. Then install the new offset dowels in the direction needed to center the bore with the crankshaft centerline.
In the example, TIR was 0.012 inch. The dowels needed for correction would have an offset of 0.007 inch (Fig. 18).
Install the dowels with the slotted side facing out so they can be turned with a screwdriver. Then install the housing, remount the dial indicator and check bore runout again. Rotate the dowels until the TIR is less than 0.010 inch if necessary.
If a TIR of 0.053 inch, or greater is encountered, it will be necessary to replace the clutch housing.
Measuring Clutch Housing Face Runout
Fig. 19:
1. Reposition the dial indicator plunger on the housing face (Fig. 19). Place the indicator plunger at the rim of the housing bore as shown.
2. Rotate the crankshaft until the indicator plunger is at the 10 O'clock position on the bore. Then zero the dial indicator.
Fig. 20:
3. Measure and record face runout at four points 90° apart around the housing face (Fig. 20). Perform the measurement at least twice for accuracy.
Fig. 22:
4. Subtract the lowest reading from the highest to determine total runout. As an example, refer to the sample readings shown (Fig. 22). If the low reading was minus 0.004 inch and the highest reading was plus 0.009 in., total runout is actually 0.013 inch.
5. Total allowable face runout is 0.010 inch. If runout exceeds this figure, runout will have to be corrected. Refer to Correcting Clutch Housing Face Runout.
CORRECTING CLUTCH HOUSING FACE RUNOUT
Fig. 21:
Housing face runout, on gas or diesel engines, can be corrected by installing shims between the clutch housing and transmission (Fig. 21). The shims can be made from shim stock or similar materials of the required thickness.
As an example, assume that face runout is the same as shown in (Fig. 22) and in Step 4. In this case, three shims will be needed. Shim thicknesses should be 0.009 inch (at the 0.000 corner), 0.012 inch (at the -0.003 corner) and 0.013 inch (at the -0.004 corner).
After installing the clutch assembly and housing, tighten the housing bolts nearest the alignment dowels first.
During final transmission installation, install the shims between the clutch housing and transmission at the appropriate bolt locations.