Dana Spicer Rear Drive Axle Component Failures

Dana-Spicer Model 60, 70 and 80 rear drive axles equip many Dodge, Ford, GM, IHC, and Jeep to 1 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.

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.

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 most of these axles is set with selective shims between the outer pinion gear bearing and pinion shoulder. 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 unless a more frequent interval is specified in your owners manual. 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.

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.

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 Ford and 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.
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!