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Dana-Spicer Model 60, 70 and 80 rear drive axles equip
many Dodge, Ford, GM, IHC,
and Jeep ¾ to 1¼
ton trucks. Dana 60 and standard model 70 axles share
the same differential and outer pinion bearings. Dana
70HD and Model 80 axles have larger differential bearing
and spacers between the differential bearing cups and
differential housing. Dana 80 axles also have much
larger pinion bearings than the 60's and 70's.
The
basic design of these axles is well proven, but like any
mechanical device, proper maintenance and lubrication is
essential to obtain a satisfactory service life. There
are also serious durability problems with the
differential bearings associated with the combination of
Diesel or big gas power and heavy loads.
Badly pitted Differential Bearing Cup from a
Model 70 after 143,000 miles. This bearing is
from a Dodge W350 1 ton truck with a 360 gas
engine.
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The
most common parts failure problem with these axles
coupled to high horsepower engines is reduced
differential bearing life. Tremendous pressure is put
on the differential bearings under high load/high torque
situations. After 125,000 miles or so, the bearings and
races will be worn and pitted. From this point,
friction between the bearing components increases until
the press fit inner bearing race will start to slip on
the differential bearing hub. This slipping action
starts to wear into the hub and tear the adjusting shims
that fit between the differential and bearing cone.
Once the shims tear through, they fall out, which
effects differential bearing preload, plus backlash
between the ring and pinion. The drivers side bearing
is usually the one that fails first which can
substantially increase the backlash from the recommended
.005”-.008”. If the problem is on the passenger side,
backlash is decreased to the point the ring and pinion
teeth are metal to metal. In either case, it’s bad news
which can quickly lead to gear, differential, and/or
rear antilock brake failure.
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Model 60 and 70 Differential Bearing Cups often
Wear into the Narrow Differential Bore Face.
This condition will alter backlash and
accelerate bearing wear. The worn faces can be
trued with the
QT1000 Differential Bore Facing Tool
QT1000 Ready to Reface Bores |
Cocked
differential bearing cups are a common problem with
Model 60 and 70 axles. The rear part of the
differential bearing bore face is a relatively narrow
raised casting. Under repeated high torque loads
typical of hard working, big engine trucks, the
differential bearing cup will slowly wear into the
narrow casting which cocks the cup and causes uneven
bearing wear. Again, the problem most commonly occurs
with the drivers side bearing. If not caught early, the
axle housing bearing bore faces will require refacing
with the QT1000 refacing tool. Ring and pinion tooth
breakage is common with advanced cases. This problem
does not normally occur with Model 80 axles, which have
steel spacers between the cup and bore face.
As a rule, the pinion bearings will outlast the
differential bearings, but they should be replaced any
time differential bearings are replaced. The pinion
preload on these axles is set with selective shims
between the outer pinion gear bearing and pinion
shoulder. Initial preload with new bearings should be
20-40 inch lbs.. As the bearings wear, pinion preload
is gradually reduced until there is no preload.
Continued wear can cause gear damage or pinion seal
leaks.
Checking Pinion Preload by rotating pinion with
an inch-pound torque wrench. |
Vehicle manufacturer recommendations for lubricant
service vary with later model trucks, often using
synthetic gear lubes. (I am a firm believer in modern
synthetics for all axle lubrication.) For instance, for
some years Dodge has no scheduled rear axle oil
change interval for trucks operated under normal service
(Maintenance Schedule A), and a 12,000-15,000 mile
interval depending upon year for severe duty service
(Maintenance Schedule B). To minimize bearing wear, we
recommend trucks operated under normal service have the
rear axle lubricant changed every 2 years, or 30,000
miles. We also recommend the rear differential and
pinion bearings be replaced on hard working Diesel and
large gas engine trucks after 125,000 miles to prevent
major component failures caused by excessive bearing
wear. At the same time, the differential thrust
washers, pinion mate gears, side gears, cross shaft, and
limited slip clutch packs should be checked for wear and
worn parts replaced. For parts, we advise using only
genuine Dana-Spicer components which are reasonably
priced and readily available as individual pieces or
kits
Side Gear Thrust Washers After 147,500 Miles.
Axle lubricant was never changed.
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The 125,000 mile interval is also a convenient time to
inspect the wheel bearings for wear and check the axle
vent for blockage which can cause pressure to build up
in the axle until relieved by seal failure.
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Broken vent hose allowed dirt to clog axle vent.
As axle warmed up during use, expanding air in
axle caused wheel seals to fail. Oil
contamination on the brakes shoes led to erratic
brake performance and permanent damage to the
brake friction material. |
We see
a lot of problems with the outer wheel bearing wearing
into the spindle nuts on 1979-1984 Ford
and 1979-2002 Dodge trucks with elastic stop nuts
and lock wedges. For these years, we replace the
original single nut and wedge with a spindle nut upgrade
set that consists of a thrust washer, lockwasher, two
nuts, and an axle shaft gasket. This upgrade is
available in a kit with a spindle nut socket.
(left) Original single spindle nut with wedge.
(right) Double spindle nut upgrade set from
QK4000 Spindle Nut Kit.
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Improper wheel bearing adjust often leads to
leaking seals or failed bearings. A chisel is
not the appropriate tool to adjust your
spindle nuts. Use a torque wrench and the
correct spindle nut for your application! |
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