GMC 1989 Light Duty Truck Repair Manual page 264

4C2-10 9 /4-INCH RING GEAR FRONT AXLE
3
Figure 26—Scooter Gage on the Height Block
• This reading indicates the amount of shims
needed for a nom inal pinion setting. The
pinion marking may change the pinion depth
by adding or deleting shims from the nominal
pinion setting.
• A positive ( + ) pinion marking indicates that the
distance between the ring gear centerline and the
pinion head m ust increase by the num ber of
thousandths marked on the pinion. This means that
the shim pack will decrease by the same number of
thousandths.
• A negative (-) pinion marking indicates that the
distance between the ring gear centerline and the
pinion head m ust decrease by the num ber of
thousandths marked on the pinion. This means that
the shim pack will increase by the same number of
thousandths.
• A pinion etched zero (0) will use the nominal setting
as determined in this procedure.
Figure 2 7 — S coo ter G age on th e A rbor