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Home >> GMC >> 1982 >> Magnavan Standard Trans >> Repair and Diagnosis (Single Page) >> Drivelines & Axles >> Differentials & Drive Axles >> Drive Axles - General Motors 7 1/2", 8 1/2", 8 7/8", & 9 1/2" Ring Gear >> Overhaul >> Reassembly & Adjustment >> Side Bearing Preload

Side Bearing Preload

  1. Lubricate bearings, and place differential assembly into position in housing. Hold in place by hand.
  2. Install bearing strap (J-22779-6) on left bearing. Tighten bolts evenly to a snug fit. Install right bearing cap. Tighten bolts to a snug fit.
  3. Position ring gear tight against pinion, so that backlash is 0.000 - 0.001" (0 - 0.025 mm). Insert gauging tool (J-22779) between left bearing cup and carrier housing.
  4. While moving tool up and down, tighten adjusting nut until a slight drag is felt. Tighten lock bolt on side of tool.
  5. Install 0.170" (4.32 mm) adjustment spacer and shim between right bearing and carrier. Insert a feeler gauge, thick enough to create a slight drag, between shim and carrier.
  6. To determine correct side bearing shim thickness, measure thickness of adjusted gauging tool. Record measurement. Add together dimensions of shim, spacer and feeler gauge. Record measurement.
  7. Subtract 0.010" (.25 mm) from ring gear (left) side measurement and add 0.010" (.25 mm) to opposite (right) side measurement. This allows for correct backlash adjustment.
  8. To obtain correct preload, add 0.004" (10 mm) to both measurements. The total is the correct shim pack thickness for each side.

    Example:

    Ring Gear Side (Left) Shim Pack

    .250" (Gauging Tool Measurement)

    -.010" (Backlash Adjustment)

    +.004" (Bearing Preload)

    =.244" (Ring Gear Side Shim Pack)

    Opposite Ring Gear Side (Right) Shim Pack 0.265" (Combined Measurement Total)

    +.010" (Backlash Adjustment)

    +.004" (Bearing Preload) =.279" (Opposite Ring Gear Side Shim Pack)

  9. Install ring gear side shim first. Wedge opposite side shim between bearing cup and spacer. Install shim so that chamfered side is against spacer.
    NOTE: If shim is not chamfered enough, and it scrapes spacer when it is installed, file or grind chamfer before installation.
  10. It may be necessary to partially remove differential, when right side shim is being installed. Tap shim into place with a soft-faced hammer. Tighten bearing cap bolts.
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