Differential: Overhaul Mazda MX-5 NB

Disassembly (Standard Type)

1. Mount carrier in Differential Carrier Hanger (49-M005-561). Mark side bearing caps for reassembly reference. Remove adjuster lock plates (if equipped). (Scheme 4)
2. Loosen side bearing cap bolts and slightly back off adjusters. Remove side bearing caps. Remove differential assembly from carrier. Mark side bearing races for reassembly reference. Remove adjusters and side bearing races from differential.
3. Remove drive pinion lock nut and washer. Remove companion flange using Puller (49-0839-425C). Remove oil seal, spacer, outer bearing and collapsible spacer from carrier. Remove drive pinion, spacer and inner bearing assembly from carrier. Remove bearing races using a drift and hammer in slots provided on inner lip (as necessary).
4. Remove ring gear retaining bolts. Separate ring gear from differential case. Mark side bearings for reassembly reference. Using Puller (49-0839-425C), remove side bearings from differential case. Remove knock pin. Remove pinion shaft, pinion gears, thrust washers, and side gears. (Scheme 4)

Scheme 4

Scheme 5

Scheme 6

1. Install side gears, thrust washers, pinion gears and pinion shaft. Position dial indicator against pinion gear. (Scheme 5) Secure one side gear.
2. Check side gear and pinion gear backlash. If backlash exceeds.004" (.10 mm), replace thrust washers. See «THRUST WASHER SPECIFICATIONS»(ref-4734-S35631415922000072100000) table. Install and stake knock pin. Noting marks made during disassembly, press side bearings onto differential assembly using Bearing Installer (49-G030-338 or 49-UB71-525) and Body (49-F401-331). THRUST WASHER SPECIFICATIONS Identifying Mark Thickness - In. (mm) 0.0787 (2.000) 05.0807 (2.050) 1.0827 (2.100) 15.0847 (2.150) 2.0866 (2.200)
3. Apply locking compound to rear face of ring gear. Install ring gear and tighten ring gear retaining bolts to 51-61 ft. lbs. (69-83 N.m). Using appropriate bearing installer set (49-G030 338) and press, install drive pinion bearing races into differential carrier.
4. Put original spacer, inner bearing and Collar (49-H027-001) on Dummy Drive Pinion (49-8531-565). (Scheme 6) Secure collar with "O" ring. Install assembly into differential carrier.
5. Install outer bearing and Collar (49-8531-567) on dummy drive pinion. Install companion flange, washer and original drive pinion lock nut. Tighten drive pinion lock nut so dummy drive pinion assembly can be turned by hand.
6. Install dial indicator on Pinion Height Gauge (49-0727-570). Place pinion height gauge on a flat surface, and zero dial indicator. Position Gauge Block (49-0305-555) on top of dummy drive pinion assembly.
7. Place pinion height gauge on top of gauge block. Position dial indicator to measure distance to a point where side bearing sits. Measure lowest point. (Scheme 6) Measure both sides. Add both measurements together and divide by 2.
8. If result is not zero, replace pinion spacer. Spacers are available in a range of.1213-.1366" (3.080-3.470 mm) in.001" (.03 mm) increments. Remove dummy drive pinion. Press rear bearing onto drive pinion.
9. Install drive pinion, spacer, front bearing, collapsible spacer and companion flange in differential carrier. DO NOT install pinion oil seal yet. DO NOT exceed one-ton force, or collapsible spacer will be damaged.
10. Install washer and drive pinion lock nut. Temporarily tighten drive pinion lock nut. Turn companion flange by hand to seat bearing. Using torque wrench, tighten drive pinion lock nut to specification. See «TORQUE SPECIFICATIONS»(ref-4734-S40781739572000072100000). Check pinion bearing preload at drive pinion lock nut. See «PINION BEARING PRELOAD SPECIFICATIONS»(ref-4734-S29699611182000072100000) table. If pinion bearing preload is not as specified, replace collapsible spacer and recheck preload. PINION BEARING PRELOAD SPECIFICATIONS Application INCH Lbs. (N.m) Miata 7.9-12.1 (0.9-1.3)
11. Remove drive pinion lock nut, washer and companion flange. Lubricate oil seal lip with differential oil and install pinion oil seal. Lubricate end of companion flange with grease and install companion flange and washer. Install NEW drive pinion lock nut and tighten to specification. See «TORQUE SPECIFICATIONS»(ref-4734-S40781739572000072100000). Recheck pinion bearing preload.
12. Position differential assembly into differential carrier. Install side bearing adjusters. Position side bearing caps. Align marks made during disassembly. Install side bearing cap bolts, and hand-tighten bolts.
13. Tighten side bearing adjusters equally until adjusters contact bearing races. Mark ring gear in 4 locations, 90 degrees apart. Position dial indicator against ring gear to check ring gear backlash.
14. Check backlash at all 4 locations. Tighten side bearing adjusters equally until backlash is.0035-.0043" (.09-.11 mm). Minimum backlash at any point is.002" (.05 mm). Difference between minimum and maximum backlash should not exceed.0028" (.070 mm).
15. To set differential bearing preload, tighten adjusters equally until distance between measuring points on carrier bearing caps is within specification. (Scheme 7) See «DIFFERENTIAL CARRIER DIMENSIONS»(ref-4734-S42147865172000072100000) table.
16. Ensure backlash did not change when preload was set. Tighten side bearing cap bolts to specification. See «TORQUE SPECIFICATIONS»(ref-4734-S40781739572000072100000). Check ring gear tooth patterns. See GEAR TOOTH CONTACT PATTERNS article in GENERAL INFORMATION.
17. To complete reassembly, reverse disassembly procedure. Tighten all nuts and bolts to specification. See «TORQUE SPECIFICATIONS»(ref-4734-S40781739572000072100000).

DIFFERENTIAL CARRIER DIMENSIONS

Scheme 7