Differential: Overhaul Ford Thunderbird X

Disassembly

1. Remove differential assembly. See «DIFFERENTIAL ASSEMBLY»(ref-46564-S18731112992001011500000) in REMOVAL & INSTALLATION. Remove cover. Install differential in Bench Mounted Holding Fixture (T57L-500-B). Measure and record ring gear runout and backlash. Mark differential bearing caps for reassembly reference. Loosen differential bearing cap bolts and bearing caps. NOTE: Observe direction of arrows on differential bearing caps. When installing, arrows must point in same direction as before removal. Mark position of shims, bearing cups and differential bearing caps for reassembly reference.
2. Pry differential case, bearing cups and shims from housing and remove with differential bearing caps. Remove differential side bearings with Bearing Remover (T70P-4221-A). Remove companion flange with Companion Flange Remover (T78P-4851-A). NOTE: After removing pinion nut, but before removing flange, mark pinion stem in relation to companion flange for reassembly reference. If a new gear set is installed, this is not necessary.
3. With a soft-faced hammer, drive pinion out of front bearing cone and remove through the rear of housing. Remove pinion seal and front bearing. To remove rear pinion bearing, use Pinion Bearing Cone Remover (T71P-4621-B) and Drive Pinion Bearing Installer (T53T-4621-C). Remove bearing and measure and record thickness of shim located behind bearing. NOTE: DO NOT remove pinion bearing cups unless damaged. If replacing bearing cups, bearings must also be replaced.
4. Bearing cups in housing may be removed using brass drift and hammer. Tap alternately on each side of bearing cup during removal to prevent bearing cup from binding in housing.
5. If ring gear runout exceeded .004" (.10 mm), install differential assembly with bearings and cups in housing without pinion assembly. Install a .265" (6.73 mm) shim on left side of differential assembly. Install left differential bearing cap and bolts finger tight.
6. Apply pressure toward left side of ring gear to ensure bearing is seated in bearing cup. Shim right side until slight drag is felt when inserting shim. Install differential bearing cap and bolts. Tighten bolts to 70-85 ft. lbs. (95-115 N.m). Rotate differential assembly to ensure free rotation.
7. Install dial indicator and check ring gear runout. If runout is less than .004" (.10 mm), excessive runout was caused by improper bearing preload. If runout still exceeds .004" (.10 mm), remove differential assembly.
8. Mark ring gear and differential assembly for reassembly reference. Remove ring gear bolts. Tap ring gear from differential case. Install differential case in housing as previously described. See «DIFFERENTIAL ASSEMBLY»(ref-46564-S18731112992001011500000) in REMOVAL & INSTALLATION.
9. Recheck runout on differential carrier case flange. If runout is less than .004" (.10 mm), install new ring gear and pinion. If runout exceeds .004" (.10 mm), inspect differential case or bearings for damage.
10. If bearings are not damaged, replace differential case and bearings. Remove differential side bearings with a puller. Mark differential case and ring gear for reassembly reference. Remove pinion gears, side gears and thrust washers.

Reassembly

1. If new components have been installed, proper gear set assembly must be checked using Pinion Depth Gauge (T79P-4020-A) to determine correct pinion shim thickness. See «PINION DEPTH ADJUSTMENTS»(ref-46564-S27752610712001011500000) .
2. Install new bearing cups in housing if necessary. Bearing cups must be seated in bores so a .0015" (.038 mm) feeler gauge will not fit between bearing cup and bottom of bore.
3. Install necessary shims on pinion to obtain correct pinion depth. Press inner bearing on pinion shaft. Ensure bearing is seated against shims. Lubricate pinion bearings with gear lubricant. Install pinion in housing. Install new collapsible spacer and outer pinion bearing.
4. Ensure sealing surfaces are clean and free of burrs. Using Seal Installer (T79P-4676-A), install pinion oil seal. If oil seal becomes cocked during installation, remove and replace. Lubricate oil seal lips with Lubricant (C1AZ-19590-BA or ESA-M1C75-B).
5. Check pinion and companion flange splines for burrs. Coat companion flange splines with small amount of gear lubricant. Align marks on companion flange and pinion (used pinion only). Install companion flange on pinion. Coat washer side of NEW pinion nut with gear lubricant and install nut. CAUTION: DO NOT hammer companion flange or install with power tools.
6. Using Companion Flange Holder (T78P-4851-A), hold companion flange and gradually tighten nut to obtain correct pinion bearing preload. See «PINION BEARING PRELOAD ADJUSTMENTS»(ref-46564-S06944299952001011500000) . NOTE: If desired preload is exceeded, a new collapsible spacer must be installed and pinion nut retightened until proper preload is obtained.
7. Lubricate all parts with gear lubricant. Place side gears and thrust washers into differential case. Place pinion gears and thrust washers exactly opposite each other in differential case openings, and mesh pinion gears with side gears.
8. Install ring gear with new mounting bolts. Apply Loctite to threads and torque bolts to the proper specification. See «TORQUE SPECIFICATIONS»(ref-46564-S04015156652001011500000) table at end of article. Press new bearings on differential case using properly sized sleeve. Ensure bearings are fully seated.
9. After proper shims have been chosen to obtain proper ring gear backlash and bearing preload, differential assembly may be installed. See «DIFFERENTIAL BEARING PRELOAD & RING GEAR BACKLASH ADJUSTMENTS»(ref-46564-S16668841922001011500000) .
10. Install differential assembly and bearing cups in housing. Install differential bearing caps and bolts. Tighten the differential bearing cap bolts to the proper specification. See «TORQUE SPECIFICATIONS»(ref-46564-S04015156652001011500000) table at end of article.
11. Check ring gear backlash and gear tooth contact pattern. See «GEAR TOOTH CONTACT PATTERN»(ref-46564-S05497949902001011500000) in this article. Check gear tooth contact pattern before final assembly. Pinion depth and ring gear backlash may be adjusted to obtain proper gear tooth contact pattern. When all adjustments are correct, install cover.