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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> Drivelines & Axles >> Differentials & Drive Axles >> Drive Axle - DANA Full-Floating >> Overhaul >> Differential Assembly >> Checking Ring Gear Backlash

Checking Ring Gear Backlash

  1. Mount dial indicator on drive axle housing. See Fig 1. Place dial indicator tip at heel end of ring gear tooth. Check backlash at 3 equally spaced locations.
  2. Backlash should be .005-.009" (.13-.23 mm). Variation between points checked must not vary more than .002" (.05 mm). High backlash is corrected by moving ring gear closer to drive pinion. Low backlash is corrected by moving ring gear away from drive pinion.
  3. To adjust ring gear backlash, remove differential case from housing; remove differential bearings and move proper amount of shims from one side to another.
  4. When backlash adjustment is completed, check ring gear tooth contact pattern. See GEAR TOOTH CONTACT PATTERNS article. Pattern should be correct if assembly and adjustments were done properly.
  5. With differential assembled and correctly adjusted, install new cover gasket and cover. Tighten cover bolts to specification. Install axle shafts and fill drive axle with lubricant.
    Fig 1: Checking Ring Gear Backlash
    G121086Courtesy of GENERAL MOTORS CORP.
    DRIVE AXLE ASSEMBLY SPECIFICATIONS (1)

    Application Specifications
    Ring Gear Backlash .005-.009" (.13-.23 mm)
    Pinion Bearing Preload 20-40 INCH lbs. (2.26-4.53 N.m)
    10 1/2" Ring Gear Inner Pinion Bearings
    "B" & Heavy Duty Models 1.4375" Wide
    "U" Models 1.1875" Wide
    10 1/2" Ring Gear Differential Bearings
    "B" & "U" Models 1.0000" Wide
    Heavy Duty Models 1.1875" Wide
    (1) Adjustment shims are available in .003", .005", .010", and .030" thicknesses.