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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> Drivelines & Axles >> Driveshaft & Universal Joints >> Drive Shaft & Universal Joints >> Adjustments >> Drive Shaft Balancing

Drive Shaft Balancing

  1. Drive shaft imbalance may often be cured by disconnecting shaft and rotating it 180 degrees in relation to other components. Test by raising rear wheels off ground, and turning shaft with engine.
    NOTE: DO NOT  run engine without ram airflow across radiator for prolonged periods, as overheating of engine or transmission may occur.
  2. On most models, balance testing may be done by marking shaft in 4 positions, 90 degrees apart. Place marks approximately 6" (152 mm) forward of weld, at rear end of shaft. Number marks 1, 2, 3 and 4.
  3. Place screw-type hose clamp so clamp head is in No. 1 position, and rotate shaft with engine. If there is little or no change, move clamp head to No. 2 position, and repeat test.
  4. Continue procedure until vibration is at lowest level. If no difference is noted with clamp head moved to all 4 positions, vibrations may not be drive shaft imbalance.
  5. If vibration is lessened but not completely gone, place 2 clamps at that point, and run test again. Combined weight of clamps in one position may increase vibration. If so, rotate clamps 1/2" apart, above and below best position, and repeat test.
  6. Continue to rotate clamps as necessary, until vibration is at lowest point. If vibration level is still unacceptable, leave rear clamp(s) in position and repeat procedure at front end of drive shaft. If vibration can be eliminated or reduced to acceptable levels using this test procedure, send drive shaft to balance shop for permanent balancing.
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