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Home >> Porsche >> 1985 >> 944 Automatic >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Overhaul - 087, 087E & 089 >> Final Drive Assembly >> Reassembly & Adjustments >> Pinion Depth & Bearing Preload

Pinion Depth & Bearing Preload

NOTE: If original parts are reused, use same thickness pinion depth and bearing preload adjusting shims as were removed during disassembly.
  1. Heat pinion shaft bearings to about 212°F (100°C) in oil bath. Press rear (larger) bearing onto shaft, without shims, until seated at back of gear with 3 tons of pressure. Press front (smaller) bearing onto pinion shaft with .043" (1.1 mm) test shim installed behind bearing.
    CAUTION: If pinion shaft is installed into housing without this test shim installed, it will contact housing and cause incorrect reading.
  2. Install final drive housing front cover (without oil seals) and tighten attaching bolts. Position pinion shaft in place in housing. Install rear cover (without oil seals) and tighten attaching bolts.
  3. Install Magnetic Plate (VW 385/17) onto rear end of pinion shaft. Attach dial indicator to final drive housing so indicator tip is touching magnetic plate on pinion shaft. Zero indicator. Move pinion shaft up and down (without turning) and note indicator setting. See Fig 1 .
    CAUTION: If pinion shaft is turned during measurement, readings will be incorrect due to settling of bearing.
  4. Add end play measured on dial indicator, plus .001" (.25 mm) for setting allowance (constant value), plus .006" (.15 mm) for bearing preload, plus .043" (1.1 mm) for thickness of test shim. Total is thickness of shims required to obtain correct pinion depth and bearing preload. Record total shim pack thickness.
    Fig 1: Measuring Pinion Shaft End Play
    G96I15063
  5. Remove rear cover and pinion shaft from housing. Press front pinion bearing from shaft, remove test shim, and install shims equal to total thickness determined in step  4 . Heat and press bearing back onto pinion shaft.
  6. Reinstall pinion shaft in housing. Reinstall rear cover and tighten bolts. Turn pinion in both directions several times. Install Gauge Plate (VW 385/28) on pinion shaft. See Fig 2 . Adjust the clamp ring on Universal Measuring Bar (VW 385/1) until distance "A" is 3.23" (82 mm) for 087 models or 2.28" (58 mm) for 089 models. See Fig 3 .
    Fig 2: Installing Measuring Tools For 089 Model Pinion Depth (Tool Numbers In Parentheses Are For 087 Models)
    G96C15059Courtesy of VOLKSWAGEN UNITED STATES, INC.
    Fig 3: Measuring Tools For Pinion Depth Shim Selection
    G96F15060Courtesy of VOLKSWAGEN UNITED STATES, INC.
  7. Assemble dial indicator, Centering Discs (VW 385/2), Measuring Pin (VW 385/13), Extension (VW 385/15 for 087 models; VW 385/20 for 089 models) and Master (Setting) Gauge to Measuring Bar (VW 385/1). Master gauge usage varies with model and is needed to adjust measuring bar. Universal Master Gauge (VW 385/30) will work for all models.
  8. Universal master gauge sets measuring bar to "Ro ", which is length of master gauge used in factory testing machine to measure deviation "r". Deviation "r" is found on side of ring gear and is always given in .01 mm. See Fig 4 . Different models have different "Ro " values.
  9. All 087 models have "Ro " of 46.60 mm. All 089 models have "Ro " of 40.55 mm. Individual master gauges are available. All 087 models use Master Gauge (VW 385/26). All 089 models use Master Gauge (VW 385/5). With bar assembled and master gauge in place, set dial indicator with .118" (3.0 mm) preload on all models. See Fig 3 .
  10. Lightly lubricate left adjusting ring threads with multipurpose grease. Screw left adjusting ring (with side bearing outer race installed) into final drive housing until outer surface of adjusting ring is flush with surface of housing.
  11. Insert measuring bar assembly into housing. Lubricate right adjusting ring threads. Install adjusting ring in final drive housing flush with housing. Turn knob on end of measuring bar to move centering disc outward, until bar can barely be turned by hand.
  12. Rotate measuring bar until pin extension rests squarely against gauge plate. Slowly rotate bar back and forth over center of gauge plate. Read and record maximum dial indicator deflection, calling this value "e".
  13. Subtract deviation "r" (stamped on ring gear in .01 mm; see Fig 4 ) from value "e" (recorded in step  12 ). The result gives thickness of S3 shim, which goes under rear (large) drive pinion bearing. To determine thickness of S4 shim, which goes under front (small) drive pinion bearing, subtract S3 thickness from total shim thickness (as determined in step  4 ).
  14. Shims for S3 and S4 are available in thicknesses from 1.100-1.900 mm in increments of .025 mm. Measure selected shims at several points, and check for burrs or other damage. Install selected shims and bearings on drive pinion shaft. Install drive pinion in housing and lubricate bearings with hypoid oil.
  15. Reinstall universal measuring bar (VW385/1) and ensure indicator reading agrees with deviation "r", +/-.04 mm. Remove measuring bar.
Fig 4: Identifying Numbers On Side Of Ring Gear
G96H15062Courtesy of VOLKSWAGEN UNITED STATES, INC.
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