Next, the gear tooth contact pattern is checked. Gear marking compound is applied to both the ring and pinion gear and the resulting pattern is compared to the manufacturer’s specs. To correct the pattern, a general rule of thumb is that if the pattern is heavy at the toe (top), subtract shims. If it’s heavy at the heel (bottom), add shims. At this point, it may be necessary to remove or add shims or reset the pinion to achieve the proper backlash and gear contact pattern.