Ring Gear Tooth Contact Pattern Interpretation Chart - Pinion Shim & Backlash

This document is a ring gear tooth contact pattern interpretation chart used when setting up a differential (ring and pinion gears). It shows five pairs of illustrated gear teeth, each pair depicting the contact pattern on the drive side (heel and toe labeled) and coast side (toe and heel labeled) of the ring gear teeth. Each illustration pair is accompanied by an interpretation and corrective action: (1) the normal or desirable pattern, where the drive pattern is centered on the tooth and the coast pattern is centered but may be slightly toward the toe, with clearance between the pattern and the top of the tooth; (2) backlash correct but a thinner pinion position shim is required; (3) backlash correct but a thicker pinion position shim is required; (4) pinion position shim correct but backlash should be decreased; and (5) pinion position shim correct but backlash should be increased. The figure is referenced as E6232-B. A technician can use this chart after painting the ring gear with marking compound and rotating the gears to compare the resulting contact pattern to these examples and determine whether to change the pinion shim thickness or adjust backlash.