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Home >> Buick >> 2011 >> Lucerne CX >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 9 (Automatic Transmission - 4T80-E - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> Final Drive Noise or Hum Noise

Final Drive Noise or Hum Noise

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Final Drive Noise or Hum Noise

Checks Causes
DEFINITION: A final drive noise is a whine or hum that is most noticeable under light throttle acceleration or turns on deceleration
TEST: Drive the vehicle on a section of smooth highway in 3 different speed ranges: 32-48 km/h (20-30 mph), 48-64 km/h (30-40 mph) and 64-80 km/h (40-50 mph). Determine the speed range when the noise is the most noticeable. When the noise is the most noticeable, shift the transmission into neutral and back into drive. If the noise stops when the transmission is shifted into neutral and returns when shifted back into drive, replace the final drive components listed in the table below.
When the noise remains constant in both drive and neutral, DO NOT SERVICE THE FINAL DRIVE. Additional noise diagnosis is required. Refer to Symptoms - Automatic Transmission .
OTHER POSSIBLE SOURCES OF NOISE: Accessory drive items on the engine such as power steering, A/C compressor or alternator; or the engine is grounded to the frame. Refer to Symptoms - Engine Mechanical .
Tire noise. Refer to Symptoms - Vibration Diagnosis and Correction .
  • Final Drive Carrier Assembly
  • Final Drive Sun Gear
  • Final Drive Internal Gear
 Mis-machined or damaged
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