Component Tests

Axle Vent 

A plugged vent will cause excessive seal lip wear due to internal pressure buildup. If a leak occurs, check the vent. Make sure the vent hose is not kinked. Remove the hose from the vent nipple and clear the hose of any foreign material. While the hose is removed, pass a length of mechanic's wire or a small diameter Allen wrench in and out of the vent to clean it. Connect the hose when done.

Traction-Lok® Differential Operation Check 

A Traction-Lok® differential can be checked for correct operation without removing it from the rear axle housing.

Raise only one rear wheel. Install the Differential Clutch Gauge on the wheel bolts.

Fig 1: Differential Clutch Gauge

Courtesy of FORD MOTOR CO.

Use a torque wrench with the capacity of at least 271 N.m (200 lb-ft) to rotate the axle shaft. Be 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 N.m (20 lb-ft). The initial breakaway torque may be higher than the continuous turning torque.

Fig 2: Checking Breakaway Torque

Courtesy of FORD MOTOR CO.

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. Refer to REAR DRIVE AXLE/DIFFERENTIAL - FORD 8.8-INCH RING GEAR article.

Traction-Lok® 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 operation of a Traction-Lok® 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® 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® has transferred as much torque as possible to the non-slipping wheel.

Wheel Hub or Axle Flange Bolt Circle Runout 

Fig 3: Wheel Hub or Axle Flange Bolt Circle Runout

Courtesy of FORD MOTOR CO.

1. Position the Dial Indicator with Bracketry perpendicular to the wheel hub or axle flange bolt, as close to the hub or flange face as possible. Zero the indicator to allow the pointer to deflect either way.
2. Rotate the hub or flange until the next bolt is contacted. Record the measurement and continue until each bolt is checked. The difference between the maximum and minimum contact readings will be the total wheel hub or axle flange bolt pattern runout. Runout must not exceed 0.38 mm (0.015 in).

Pilot Runout 

Fig 4: Identifying Pilot Runout

Courtesy of FORD MOTOR CO.

1. Position the Dial Indicator with Bracketry with the Clutch Housing Alignment Adapter to the pilot, as close to the hub or axle flange face as possible. Zero the indicator to allow the pointer to deflect either way.
2. Rotate the hub or flange one full turn and note the maximum and minimum readings. The difference between the maximum and minimum readings will be the total pilot runout. Pilot runout must not exceed 0.15 mm (0.006 in).

Wheel Hub or Axle Flange Face Runout 

Fig 5: Wheel Hub or Axle Flange Face Runout

Courtesy of FORD MOTOR CO.

1. Position the Dial Indicator with Bracketry on the wheel hub or axle flange face, as close to the outer edge as possible. Zero the indicator to allow the pointer to deflect either way.
2. Rotate the hub or flange one full turn and note the maximum and minimum readings. The difference between the maximum and minimum readings will be the total face runout. The runout must not exceed 0.127 mm (0.005 in).

Pinion Flange Runout Check - Circular 

1. Check the pinion flange for damage.
2. Position Drive Pinion Flange Runout Gauge on the pinion flange.
   Fig 6: Exploded View Of Circular Pinion Flange

   Courtesy of FORD MOTOR CO.

   Item	Part Number	Description
   1	-	Pilot (part of 205-319 [T92L-4851-b])
   2	-	Pinion nut
   3	205-319	Drive pinion flange runout gauge
   4	-	Bolts (2 required) (part of 205-320 [T92L-4851-C])
   5	205-320	Driveshaft clamp plate
   6	4851	Pinion flange

3. Position the Driveshaft Plate onto the Drive Pinion Flange Runout Gauge.
Fig 7: Positioning Driveshaft Plate Onto Drive Pinion Flange Runout Gauge
Courtesy of FORD MOTOR CO.
4. Align the holes on the Driveshaft Plate with the holes in the pinion flange and install the bolts. Snug the bolts evenly.
Fig 8: Aligning Clamp Plate Holes
Courtesy of FORD MOTOR CO.
5. Position the Dial Indicator Gauge with Holding Fixture as shown in illustration. Turn the Drive Pinion Flange Runout Gauge, and locate and mark the high spot on the pinion flange with yellow paint.
Fig 9: Positioning Dial Indicator Gauge With Holding Fixture
Courtesy of FORD MOTOR CO.
6. If the flange runout exceeds 0.25 mm (0.010 in), remove the pinion flange, re-index the flange one-half turn on the pinion, and reinstall it. Refer to REAR DRIVE AXLE/DIFFERENTIAL - FORD 8.8-INCH RING GEAR article.
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.
Fig 10: Checking Runout
Courtesy of FORD MOTOR CO.
8. If excessive runout is still evident after installation of the pinion flange, install a new ring and pinion. Repeat the above checks until the runout is within specifications.