Determining Total Differential Shim Pack Size; Pinion Depth Adjustment - GMC 1989 Light Duty Truck Repair Manual

Figure 20— Installing the Ring Gear Bolts
• Refer to " Determining Total Shim Pack Size" in this
section.
DETERMINING TOTAL
DIFFERENTIAL SHIM
PACK SIZE
1. Assem ble the differential case (22) to the axle
housing. The pinion must not be installed.
2. Mount a dial indicator having a minimum travel of 5
mm (0.200-inch) with a magnetic base on the ring
gear bolt side of the housing (figure 22).
3. Force the differential assembly as far as possible in
the direction towards the indicator.
4. Preload the dial indicator one half of its travel. Place
the tip of the indicator on a flat surface of the
differential, just next to a ring gear bolt. Mark this
location with a piece of chalk.
5. Zero the dial indicator.
Figure 2 1 — D ifferen tial w ith M aster B earings
9 /4-INCH RING GEAR FRONT AXLE 4C2-9
3
Figure 22— Determining Differential Shim Pack
6. Force the differential assem bly in the opposite
direction as far as it will go. Repeat this step until
the same reading is obtained. Record the number of
thousandths that the dial indicator traveled, not the
reading on the dial. This will be the measurement of
the shimpack without the bearing preload (which will
be added later).
7. Remove the dial indicator from the axle.
8. Remove the differential case from the axle housing.
• Do not rem ove the m aster b ea rin gs from the
differential.

PINION DEPTH ADJUSTMENT

Tools Required:
D-120 Master Pinion Block (Miller)
D-116-1 Pinon Height Block (Miller)
D-116-2 Master Discs (Miller)
D-115-3 Arbor (Miller)
D-115 Scooter Gage (Miller)
1. Clean the carrier bores and all the tools. The pinion
bore must be free of nicks and dirt.
2. Install D-120 to the pinion bore (figure 23).
3. Place D-116-2 onto D-115-3.
4. Install the arbor and discs into the axle housing
(figure 24).
5. Install D-116-1 onto D-120 and against the arbor
(figure 25).
6. Place D-115 onto the height block (figure 26).
• Place the gage on the lower step of the height
block. Push the gage down on the height
block. While applying pressure, set the dial
indicator at zero.
7. Slide the gage over the arbor (figure 27).
8. R ecord th e re a d in g at th e p o in t of g re a te s t
d efe lectio n (when the dial in d ica to r needle is
centered between movement to the left and to the
right).