One Piece Case
Fig. 1 Marking bearing caps:
DISASSEMBLY
1. Apply identification punch marks on the carrier, differential bearing cap and adjuster for reassembly purpose, Fig. 1.
2. Loosen the bearing cap attaching bolts and back off the adjuster slightly to relieve differential bearing preload.
3. Remove the differential assembly together with the bearing outer races. Make certain that each bearing outer race remains with its respective bearing.
4. Remove the drive pinion nut, then the pinion.
Fig. 2 Typical one-piece case differential assembly:
5. Disassemble and inspect all parts, Fig. 2. If damaged, replace as necessary.
DRIVE PINION, ADJUST
1. Ensure differential bearing support bores are clean and free of burrs.
2. Install front and rear (center and rear on 1986-888 RX-7) bearing outer races into differential carrier.
Fig. 3 Typical pinion components. Exc. 1986-88 RX-7:
3. On all models except 1986-88 RX-7, proceed as follows:
a. Place a spacer (3), rear bearing (4) and collar B (49 8531 568 for models exc. 1987-88 B2200 and B2600; 49 H027 001 for 1987-88 B2200 and B2600) onto drive pinion model (49 8531 568 for models exc. 1987-88 B2200 and B2600; 49 8531 565 for 1987-88 B2200 and B2600) and secure them with O-ring (6), Fig. 3.
b. Install assembly into carrier, ensuring head of pinion model is secure. Do not install collapsible spacer.
c. Install front bearing (8), collar A (49 8531 567 for models exc. 1987-88 B2200 and B2600; 49 H027 001 for 1987-88 B2200 and B2600) companion flange (9) and washer (10).
d. Install nut and tighten so model turns smoothly.
4. On 1986-88 RX-7 models proceed as follows:
a. Install rear bearing, spacer and drive pinion model (49 F027 001). Install center bearing, long collar, companion flange, washer and nut.
b. Tighten nut so drive pinion model can still be turned by hand.
Fig. 4 Zeroing dial indicator:
5. On all models, install dial indicator to gauge body. Place gauge body on surface plat, Fig. 4, then ``zero'' the dial indicator.
6. Place gauge block (49 0660 555 for RX-7 turbo and B2000, B2200 and B2600 w/P size differential; 49 0305 555 for RX-7 non-turbo and B2200 and B2600 w/M size differential) on drive pinion model and carefully place the gauge body adjusted in step 5 on gauge block so feeler of indicator comes in contact with lowest portion of differential bearing support bore.
7. Measurement should be taken on each bearing support bore. Record an average of reading:
a. If average is on plus side, use a spacer which is thicker by the plus value than the spacer used in step 3 or 4.
b. If average is on minus side, use a spacer which is thinner by the minus value than the spacer used in step 3 or 4.
8. Remove the gauge body and dial indicator, and check zero setting on the surface plate to make sure setting was not disturbed by handling.
9. To compensate for machining variables, the pinion has a number recorded in hundredth millimeters on the pinion face of the tapered end.
Example:
2 = +0.02 mm (+0.0008 in.)
-1 = -0.01 mm (-0.0004 in.)
a. If the pinion is marked with a plus number, subtract the specified amount on the pinion face of the tapered end from the amount determined in step 7.
b. If the pinion is marked with a minus number, add the specified amount on the pinion face of tapered end to the amount determined in step 7.
Fig. 5 Pinion spacer chart. One-piece case differential:
10. Select a pinion spacer within a tolerance of + or - 0.0012 in. (0.03 mm) from table, Fig. 5.
PINION BEARING PRELOAD, ADJUST
1. Install the collapsible spacer onto the drive pinion and install them in the carrier.
2. Place the front pinion bearing in position on the pinion. Hold the pinion fully forward and drive the pinion bearing over the pinion until seated.
3. Apply gear lubricant to the lip of the pinion oil seal and install the pinion oil seal into the carrier.
4. Install the companion flange on the pinion by tapping with a plastic hammer.
5. Install the pinion washer and nut. Before tightening the nut (when the pinion preload is zero), determine the oil seal drag by using a torque wrench.
Fig. 6 Measuring pinion bearing preload:
6. Torque pinion nut to 145 ft.lbs. (20 m-kg) for B2000 and B2200 models or 94 ft.lbs. (13 m-kg) for RX-7 models; and check preload, Fig. 6. After preload has been checked, final tightening should be done very cautiously. The pinion nut should be further tightened only a little at a time and preload should be checked after each slight amount of tightening. Exceeding preload specifications will compress the collapsible spacer too far necessitating its replacement. The maximum tightening torque for the nut is 130 ft.lbs. (18 m-kg) for models except B2000 and B2200 models or 253 ft.lbs. (35 m-kg) for B2000 and B2200 models. If the specified preload is not obtained at the maximum torque, replace the collapsible spacer.
7. While observing the preceding step, carefully set the preload drag to 7.8 to 12.2 in. lbs. (9 to 14 cm-kg) for RX-7 models; and 11.3 to 15.6 in. lbs. (13 to 18 cm-kg) for B2000 and B2200 models plus the oil seal drag determined in Step 5. If preload is measured with spring scale at bolt hole of companion flange, the preload drag is 5.5 to 8.8 lbs. (2.5 to 4.0 kg) for RX-7 models; 7.3 to 10.1 lbs. (3.3 to 4.6 kg) for B2000 and B2200 models, Fig. 6.
Fig. 7 Installing thrust washer on side gears:
ASSEMBLY
1. Install the thrust washer on each differential side gear and install these in the gear case, Fig. 7.
Fig. 8 Installing pinion gears:
2. Through the openings of the gear case, insert each of two pinion gears exactly 180 degrees opposite each other, Fig. 8.
3. Rotate the gears 90 degrees so that the pinion shaft holes of the case come into alignment with the holes in the pinion gears.
4. Insert the pinion shaft through the case and pinion gears.
Fig. 9 Measuring side gear backlash:
Fig. 10 Side gear thrust washer chart:
5. Check backlash of side gear and pinion gear, Fig. 9. Backlash should be 0 to 0.1 mm (0 to 0.004 in.) and must not exceed 0.1 mm (0.004 inch). Adjust as necessary by inserting the proper size side gear thrust washer, Fig. 10.
Fig. 11 Installing pinion shaft lock pin:
6. Install the lock pin to secure the pinion shaft. Stake the lock pin into position with a punch, Fig. 11.
7. Apply suitable locking compound to rear face of ring gear, then install ring gear to case and torque bolts to 54 to 61 ft.lbs. (7.5 to 8.5 m-kg).
8. Install each differential bearing to the gear case.
Fig. 12 Installing differential into housing:
9. Install the differential bearing outer races to their respective bearings, Fig. 12.
10. Place the differential gear assembly in the carrier, ensuring marks on the face of the pinion and ring gear tooth are in alignment.
Fig. 13 Installing bearing adjusters:
11. Note the identification marks on the adjusters and install each to its respective side, Fig. 13.
12. Install the differential bearing caps, ensuring identification marks on the caps correspond with those on the carrier, then install the attaching bolts.
13. Slightly tighten one of the bearing cap bolts on each side and adjust the backlash.
Fig. 14 Measuring ring & pinion backlash:
Backlash, Adjust
1. Check the backlash between ring gear and drive pinion. With wrench (490259 720), Fig. 14, turn both bearing adjusters equally until the backlash becomes 0.0075 to 0.0083 inch (0.19 to 0.21 mm) 1984 B2000 and B2200; 0.0035 to 0.0043 inch (0.09 to 0.11 mm) for RX-7, 1986 B2000 and 1987-88 B2200 and B2600.
Fig. 15 Measuring distance between bearing caps:
2. Preload on the differential bearings is obtained by tightening the adjusters. Tighten the adjusters until the distance between both pilot sections on bearing caps is 7.3004 to 7.3033 inch (185.428 to 185.5 mm) for RX-7 non-turbo, 1986 B2000 and 1987-88 B2200 and B2600 w/M size differential; 8.0485 to 8.0513 inch (204.428 to 204.5 mm) for 1984 B2000 and B2200, RX-7 turbo and 1987-88 B2200 and B2600 w/P size differential, Fig. 15. When adjusting preload, care must be taken not to disturb backlash of drive pinion and ring gear.
3. Torque bearing cap bolts to 27 to 38 ft.lbs. (3.8 to 5.3 m-kg) for RX-7, 1986 B2000 & 1987-88 B2200 and B2600 w/M size differential; 47 to 56 ft.lbs. (6.5 to 7.7 m-kg) for 1984 B2000 and B2200; 41 to 59 ft.lbs. (5.6 to 8.2 m-kg) for 1987-88 B2200 and B2600 w/P size differential.
4. Install the adjuster lock plates on the bearing caps to prevent the adjusters from loosening.
Fig. 16 Correct pinion to ring gear contact:
5. Check the tooth contact of the ring gear pinion by applying a thin coat of red lead on both sides of about six to eight ring gear teeth and rotating the ring gear a few times in both directions. Pinion position and backlash contact pattern should be as shown in Fig. 16.