can assemble a driveshaft in phase. If a driveshaft is not marked with timing arrows, do
it yourself. Make a light score mark using a steel scriber.
Figure 8-50 - Driveshaft in phase.
4.2.1 Driveshaft Inspection
Driveshafts should be routinely inspected and lubricated. Driveline vibrations, U-joint
failures, and hanger bearing problems are caused by such things as loose end yokes,
excessive radial play (side-to-side), slip spline play, bent driveshaft tubing, and missing
lube plugs in slip joint assemblies.
You can limit driveshaft performance problems by performing some simple inspection
procedures each time the driveshaft is lubed.
1. Check the yokes on both the transmission and drive axle(s) for looseness. If
loose, disconnect the driveshaft and re-torque the end yoke retaining nut to the
OEM specification. If this does not correct the problem, yoke replacement may
be required. If you do not have to replace the yoke, check the OEM
recommendation regarding replacement frequency of the end yoke retaining nut.
2. If end yokes are tight, check for excessive radial looseness of the transmission
output shaft and drive axle input and output shafts in their respective bearings.
Consult transmission and OEM specifications for acceptable radial looseness
limits and method of checking. If the radial play exceeds the specifications, the
bearing should be replaced.
3. Check for looseness across the U-joint bearing caps and trunnions. This
looseness should not exceed the OEM specification (typically as little as 0.006
inch).
4. Check the slip splines for radial movement. Radial looseness between the slip
yoke and the driveshaft stub should not exceed the OEM specification (typically
as little as 0.007 inch).
5. Inspect the driveshaft for damage, bent tubing, or missing balance weights.
Ensure there is no buildup of foreign material on the driveshaft, such as asphalt
or concrete. Anything adhering to the driveshaft has the potential to unbalance it.
6. Check the hanger bearing visually, making sure it is mounted securely. Check for
damaged seals, rubber insulator failure, or lubricant leaking from the bearing.
NAVEDTRA 14050A
8-54