Spicer Steer and Drive Wheel Ends Service Manual - Manual (Page 9)

7
Maintenance &
Inspec
ti
on
Maintenance & Inspection
Maintenance and Inspection Requirements
Drive Axle Shaft to Drive Hub Gasketed
Joint Failure
High torque applications can cause field failures of the drive
axle shaft to hub joint. This joint has two major functions. One
function is to seal the joint so the lubricant in the drive axle
and hub does not leak. The second function is to transfer the
drive torque from the drive axle shaft to the drive hub.
The requirement of the first function (stop oil leak) is currently
being met by U.S. original equipment truck manufacturers
with a gasket.
The second requirement (transfer of torque) is met by the
clamp force that is created by the eight each 5/8” or 3/4” drive
studs and nuts that are used to hold the hub and drive axle
shaft together. Holes in the drive axle shaft have clearance
around the stud to accommodate the tolerance of hole size
and location and stud size and location. Thus, all the drive
toruq is tranferred from the drive axle shaft to the hub by the
“friction” created by the clamp force on the joint. There are
two significant factors that affect the ability of the joint to
function under high torque applications.
1. Higher clamp forces create higher friction between
the drive axle and gasket and between the gasket and
the hub. Higher friction can transfer higher torque.
Thus, clamp force is a significant factor in the ability
of the joint to transfer torque.
2. The torque is transferred by friction from the drive
axle to the contacting side of the gasket, then
through the thickness of the gasket to the other side
of the gasket, and then the friction at that surface
transferes the torque to the hub. Clamp force creates
the friction that transfers torque from one surface to
the next, however, the gasket material itself must
transfer the torque through the thickness of the gas-
ket. Thus, gasket material is the other significant fac-
tor in the ability of these joints to transfer torque.
Field Service Proposal
1. Joints that have failed may have rotated the drive
axle shaft against the drive stud when the friction
and/or gasket strength was overcome. The pounding
of the drive axle against the stud can cause the drive
stuf to come loose (this is like wiggling a fence post
back and forth so you can pull it out of the ground.)
Use a stud driver and torque wrench to reinstall the
stud into the hub with 40 lbs-ft. Severe cases may
require replacement of the hub and/or stud.
2. Use gaskets made from material that is appropriate
for the application. Not all original equipment truck
manufacturers are using gaskets that meet these
requirements. Cured Armstrong N-8092, or equiva-
lent, has proven to be adequate for most applica-
tions.
3. Use SAE Grade 8 nuts and hard washers. If hard
washers are difficult to find, use Caterpillar 5/8” hard
washer 5P-8247, or the equivalent, in 3/4” diameter.
4. Assemble the joint with 200 - 230 lbs-ft of torque on
5/8” studs and 250 - 290 lbs-ft of torque on 3/4”
studs.
5. If the studs or hubs fail during assembly, it may be
that they were badly damaged when the joint origi-
nally failed. Replace parts that fail during assembly.
6. Re-torque drive flange nuts after one day of use.
Inspection Requirements
The following inspection criteria are intended for units whose
vocation is strictly on-highway use only. The inspection crite-
ria are not intended for unitized or pre-set wheel ends, refer to
systems manufacturer for inspection and service recommen-
dations.
These recommendations depend on the proper assembly of
the system, including the proper lubricant fill level.
Damaged Spacer - LMS™
There is little likelihood of damage to the spacer in operation.
If these components are damaged during a hub removal,
replace with Dana supplied spacer. In the interim, the wheel
end can be reassembled without the spacer, using standard
bearing setting procedures (Reference TMC RP-618).
Damaged Hub Cap - LMS™ Steer and Trailer
(Broken window, stripped pipe plug, etc.) Replace broken
component and refill to proper level with approved synthetic
lubricant. For warranty continuance, the replacement hub cap
must be Spicer branded. If the hub cap is removed from the
hub, a new gasket is required.