GMC 1989 Light Duty Truck Repair Manual page 208

4B5-20 DANA REAR AXLES
Figure 60— Installing the Ring Gear Bolts
DETERMINING TOTAL DIFFERENTIAL SHIM
PACK SIZE — B OR U MODEL
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
0.200-inch with a magnetic base on the ring gear
bolt side of the housing (figure 62).
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 on the
differential, just next to a ring gear bolt. Mark this
location with a piece of chalk.
5. Zero the dial indicator, w hile still fo rcin g the
differential towards the dial indicator.
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 shim pack without the bearing preload (which
will be added later).
F igure 6 1 — D ifferen tial w ith the M aster B earings
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.
DETERMINING TOTAL DIFFERENTIAL SHIM
PACK SIZE — HEAVY DUTY MODEL
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
0.200-inch with a magnetic base on the ring gear
bolt side of the housing (figure 62).
3. Install the outboard spacer between the master
bearing and the axle housing on the ring gear side.
4. Force the differential assembly as far as possible in
the direction towards the indicator.
5. 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.
6. Zero the dial indicator, w hile still fo rcin g the
differential towards the indicator.
7. 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 reading plus the spacer
measurement Will be the thickness of the spacer
and shims required.
8. Remove the dial indicator from the axle.
9. Remove the differential case from the axle housing.
10. Remove the spacer (43) from the 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) (60 and
70 U)
D-137 Master Pinion Block (70B and 70 H.D.)
D-116-1 Pinion Height Block (Miller)
D-116-2 Master Discs (Miller)
D-115-3 Arbor (Miller)