TM10-3930-660-34 16-21.  PISTON PUMP - REPAIR (Cont’d) Example: Let’s assume the depth readings were 0.029 and 0.027 inches.  Add these two figures together and divide by two to obtain the average (nominal value): 0.029 + 0.027 = 0.056 0.056/2 = 0.028 (nominal calculated value) Nominal Calculated Value - Nominal Preload Value = Required Shim Thickness 0.028 - 0.008 = 0.020 inches of shim thickness NOTE If calculated shim thickness is greater than 0.020 inches,  another shim must be added to the opposite side of the yoke to reduce total shim thickness to less than 0.020.Shim thickness at either pintle must not exceed 0.020 inches. This is necessary to provide proper O-ring compression and prevent pintle seal leakage. d.  Install correct shims (27). e.  Install pintle cover (29) and cross tighten cover screws (28) to 175-185 lb.  in. NOTE Yoke (26) rotation will be stiff,  but should be loose enough to be moved by hand (approximately 20 lb. in. torque). This tightness/drag indicates that bearings (31) are preloaded. If yoke (26) cannot be moved by hand,  preload is too great and the preload adjustment must be repeated until correct. 16-137