Lesson 1
MAINTENANCE OF PROPELLER SHAFTS AND UNIVERSAL JOINTS
Inspection Procedures
Serviceability of propeller shafts, slip joints, and universal joints can be determined by
inspection while they are installed on the vehicle. In general, these parts are inspected in
the same manner on all vehicles. If a rear propeller shaft is to be inspected, place chocks
in the front and rear of the front wheels. Raise the wheels connected to the propeller
shaft being examined so the wheels are free to turn.
Look the propeller shaft over carefully for big dents that would cause it to be bent or out
of balance. Inspect for breaks or cracks at the welded seams at each end. Clean off
excess dirt or tar that may be stuck to the shaft causing it to be unbalanced. Check for
proper mounting, making sure that the propeller shaft has been installed with the slip
joint end nearest the transmission. Also, make sure the yokes on each end of the
propeller shaft are aligned.
Examine the slip joint oil seal and the universal joints. Make sure that the slip joint oil
seal cover is in place and is tight. The universal joint mounting bolts must be tight and
must have no stripped threads. Check each universal joint bearing for breaks or cracks.
Cracks usually occur in the bearing at the inside of the yokes. At this time, inspect for
missing and cracked bearing grease seals, which are also at the inside of the yokes. Look
for broken or missing bearing retaining snap rings.
Universal joints and slip joints should be properly lubricated before you inspect for
looseness. Lubricate the joints according to the lubrication order for the particular
vehicle that you are working on. All grease fittings that have been damaged badly should
be replaced. A fitting should also be replaced if grease does not pass through it easily or
if grease comes out of the fitting after the grease gun is removed. After lubricating, shake
the propeller shaft and note any looseness. With the hand brake applied and the wheels
off the ground, attempt to rotate the propeller shaft back and forth, again noting any
looseness. No looseness is allowed at the universal joint bearings, but a very small
amount of slack is normal at the slip joint splines. Place the transmission in neutral and
turn the propeller shaft by hand and listen for squeaking, grinding, or grating sounds.
These noises indicate improperly lubricated or defective bearings.
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