Differential Assembly: Testing and Inspection
Driveline System
Component Tests
Traction-Lok(R) Differential Operation Check
A Traction-Lok(R) differential can be checked for correct operation without removing it from the rear axle housing.
Raise and remove only one rear wheel. Install the Differential Gauge on the wheel bolts.
Use a torque wrench with the capacity of at least 271 Nm (200 lb-ft) to rotate the axle shaft. Make sure that the transmission is in NEUTRAL, and that one rear wheel is on the floor while the other rear wheel is raised off the floor. The breakaway torque required to start rotation must be at least 27 Nm (20 lb-ft). The initial breakaway torque may be higher than the continuous turning torque.
The axle shaft must turn with even pressure throughout the check without slipping or binding. If the torque reading is less than specified, check the differential case for incorrect assembly.
Traction-Lok(R) Differential Check Road Test
1. Place one wheel on a dry surface and the other wheel on ice, mud or snow.
2. Gradually open the throttle to obtain maximum traction prior to break away. The ability to move the vehicle demonstrates correct performance of a Traction-Lok(R) rear axle assembly.
3. When starting with one wheel on an excessively slippery surface, a slight application of the parking brake may be necessary to help energize the Traction-Lok(R) feature of the differential. Release the brake when traction is established. Use light throttle on starting to provide maximum traction.
4. If, with unequal traction, both wheels slip, the limited slip rear axle has done all it can possibly do.
5. In extreme cases of differences in traction, the wheel with the least traction may spin after the Traction-Lok(R) has transferred as much torque as possible to the non-slipping wheel.
Pinion Flange Runout Check - Circular
NOTICE: Pinion bearing preload must be reset if the pinion nut has been loosened or removed for pinion flange reindexing or replacement or damage to the component may occur.
1. Position the vehicle on a hoist. For additional information, refer to Jacking and Lifting Service and Repair.
2. Remove the driveshaft. Refer to Driveshaft Removal and Replacement.
3. Check the pinion flange for damage.
4. Position the Drive Pinion Flange Runout Gauge and Driveshaft Clamp Plate on the pinion flange.
5. Align the holes on the Driveshaft Clamp Plate with the holes in the pinion flange and install the bolts. Snug the bolts evenly.
6. Position the Dial Indicator Gauge with Holding Fixture as shown. Turn the Drive Pinion Flange Runout Gauge, and locate and mark the high spot on the pinion flange with yellow paint.
If the flange runout exceeds 0.25 mm (0.010 in), remove the pinion flange, reindex the flange one-half turn on the pinion, and reinstall it. Refer to Rear Drive Axle/Differential - Ford 9.75-Inch Ring Gear Service and Repair or Front Drive Axle/Differential for the flange removal and installation procedures.
7. Check the runout again. If necessary, rotate the flange until an acceptable runout is obtained. If the flange runout is still more than 0.25 mm (0.010 in), install a new pinion flange.
8. If excessive runout is still evident after replacement of the pinion flange, install a new ring and pinion. Repeat the above checks until the runout is within specifications.
9. Install the driveshaft. Refer to Driveshaft Removal and Replacement.
Tooth Contact Pattern Check - Gearset
1. To check the gear tooth contact, paint the gear teeth with a marking compound. A mixture that is too wet will run and smear; a mixture that is too dry cannot be pressed out from between the teeth.
2. Use a box wrench on the ring gear bolts as a lever to rotate the ring gear several complete revolutions in both directions or until a clear tooth contact pattern is obtained.
3. Certain types of gear tooth contact patterns on the ring gear indicate incorrect adjustment. Incorrect adjustment can be corrected by readjusting the ring gear or the pinion.
Contact Pattern Location
In general, desirable ring gear tooth patterns must have the following characteristics:
- Drive pattern on the drive side ring gear well centered on the tooth.
- Coast pattern on the coast side ring gear well centered on the tooth.
- Clearance between the pattern and the top of the tooth.
- No hard lines where the pressure is high.
Acceptable ring gear tooth patterns for all axles.
Correct backlash with a thinner pinion position shim required.
Correct backlash with a thicker pinion position shim required.
Correct pinion position shim that requires a decrease in backlash.
Correct pinion position shim that requires an increase in backlash.
