Determining Correct Pinion Starting Shim Adjustments

NOTE: Ring and pinion gears are serviced as matched set only. They are identified by numbers etched on gear and pinion. See Fig 1 . The first 2 numbers identify matched set. Second number on pinion gear is pinion depth variance. This number indicates amount (in thousandths of an inch) gear set varied from standard setting. Standard setting of Cherokee, Comanche and Wrangler with 7 9/16" axle is 2.095" (53.21 mm) on a rear axle, or 2.25" (57.1 mm) on a front axle. Standard setting of Grand Wagoneer is 2.625" (66.67 mm) on all axles. Variance can be a plus or minus number.

Fig 1: Matching Ring & Pinion Gear Set

Courtesy of CHRYSLER MOTORS.

1. If original ring and pinion is being installed, use original shim. If new parts (gear set) is being installed, use following steps to determine best starting shim thickness.
2. Check numbers etched on drive pinion and ring gear. Measure thickness of original pinion shim. Note variance number on pinion gear. See Fig 1 . Note where old and new pinion marking columns intersect on chart. See appropriate PINION VARIANCE SPECIFICATIONS  .
   Fig 2: Checking Carrier Bearing End Play & Runout

   Courtesy of CHRYSLER MOTORS.
3. The intersecting figure represents the amount needed to add or subtract to the original shim. For example, if old pinion is +1 and new pinion is -3, intersecting figure is +.004" (+.10 mm). Add this amount to original shim. If the old pinion is -3 and new pinion is -2, intersecting figure is -.001" (-.025 mm). See the appropriate PINION VARIANCE SPECIFICATIONS  . Subtract this amount from original shim.