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Home >> GMC >> 1990 >> S15 Jimmy RWD, Automatic, 700R4/MD8 >> Repair and Diagnosis >> Drivelines & Axles >> Differentials & Drive Axles >> Drive Axle - 7.5", 7.625", 8.5" & 9.5" >> Overhaul >> Backlash & Final Assembly

Backlash & Final Assembly

  1. Rotate case several times to seat bearings. Check backlash at 4 locations around outside edge of ring gear using a dial indicator mounted to axle housing. Install indicator in line with gear rotation and perpendicular to tooth angle. Pinion must be held steady while taking readings. Variation should not exceed .002" (.05 mm).
  2. If backlash is incorrect, adjust side bearing shims as necessary. After adjustment is completed, make a tooth contact pattern test and make any necessary corrections. Install axle shafts and housing cover. See Fig 1 .
NOTE: Total shim pack thickness for right and left side combined must not be changed. If a shim is removed from one side, same thickness shim must be added to other side.
AXLE ASSEMBLY SPECIFICATIONS

Application Specifications: In. (mm)
Ring Gear Backlash .005-.009 (.13-.23)
Side Bearing Preload .008 (.20)
INCH Lbs. (N.m) 
Pinion Bearing Preload
7 1/2" & 7 5/8" Ring Gear
Used Bearings 8-12 (1.0-1.4)
New Bearings 24-32 (2.7-3.6)
8 1/2" & 9 1/2" Ring Gear
Used Bearings 10-15 (1.1-1.7)
New Bearings 20-25 (2.3-2.8)
Fig 1: Exploded View of 8 1/2" Ring Gear Axle Assembly
G71749Courtesy of GENERAL MOTORS CORP.