hitting the yoke plug and knocking it out; check
the driveshaft for proper length.
U-Joint Lubricating
1.
Wipe all old grease and dirt from each U-joint
grease fitting. See
, Ref. 8.
2.
Use a hand-type grease gun, or a high-pressure
gun with a low-pressure adapter, to lubricate the
U-joints.
NOTE: If a low-pressure adapter is not used
with the high-pressure gun, the U-joints may not
receive enough lubricant.
3.
Using lithium 12 hydroxy stearate grease (NLGI
grade 1 or 2, with EP additives), lubricate until
new grease can be seen at all four U-joint seals.
IMPORTANT: Fresh lubricant must be seen es-
caping from
all four bearing cup seals of each
U-joint.
On full-round yokes, if most of the grease being
added to a U-joint can be seen escaping from
just one of the U-joint seals, bend the tabs of
the lockstrap away from the heads of the bear-
ing cup capscrews, then check the torque on
the bearing cup capscrews at that seal. Tighten
the bearing cup capscrews as follows:
5/16–24 capscrews: 24 lbf·ft (32 N·m)
3/8–24 capscrews: 37 lbf·ft (50 N·m)
Bend the lockstrap tabs up, against a flat side of
each capscrew. If the capscrews were already
tight, or all of the U-joint seals still do not purge,
remove the bearing cup at that seal, and exam-
ine the seal for damage. If the seal is damaged,
replace the complete U-joint assembly.
If grease does not appear at one of the seals,
use a screwdriver to pry the U-joint trunnion
away from the non-purging seal, or tap the
driveshaft or yoke with a plastic or rawhide mal-
let (on the side opposite the dry seal), while
continuing to apply gun pressure. If grease still
does not appear, bend the tabs of the lockstrap
away from the heads of the bearing cup cap-
screws, then loosen the bearing cup capscrews
(at the bearing with the dry seal) to relieve seal
tension. Lubricate the U-joint until the old
grease is purged, then tighten the capscrews to
the above specifications, and bend the tabs of
the lockstrap against a flat side of each cap-
f410110b
06/13/96
A
A
B
C
C
D
A. Measurement: 3" (76 mm)
B. Measurement: 0.005" (0.127 mm)
C. Measurement: 0.010" (0.254 mm)
D. Measurement: 0.015" (0.381 mm)
Fig. 3, Driveshaft Runout Specifications
f410050a
10/20/93
1
1
2
3
3
3
4
5
6
7
8
A
A. After grease appears, cover the pressure-relief hole
while continuing to lubricate.
1.
Slip-Joint Grease
Fitting (with grease
gun attached)
2.
Yoke Plug
3.
Grease
4.
Half-Round Yoke
5.
Yoke Plug Pressure-
Relief Hole
6.
Slip-Joint Seal
7.
Full-Round Yoke
8.
U-Joint Grease Fitting
Fig. 4, Slip-Joint and U-Joint Lubricating
Driveline
41
School Bus Chassis Maintenance Manual, April 1998
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