Backlash

1. Check the backlash between ring gear and drive pinion. With wrench tool No. 490259 720, or equivalent, Fig. 14, turn both bearing adjusters equally until the backlash becomes; 0.0035 to 0.0043 inch (0.09 to 0.11 mm) for RX-7 and 1993 Pickup models.

Fig. 14 Ring & Pinion Backlash Measurement:

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), Fig. 15. When adjusting preload, care must be taken not to disturb backlash of drive pinion and ring gear.

Fig. 15 Distance Measurement Between Bearing Caps:

3. Torque bearing cap bolts to 27 - 38 ft.lb. for RX-7 and 1993 Pickup models with M size differential or 47 - 56 ft.lb. for 1993 Pickup models with P size differential.
4. Install the adjuster lock plates on the bearing caps to prevent the adjusters from loosening.
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.

Fig. 16 Correct Pinion To Ring Gear Contact: