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Bobcat T86 Track Motor Planetary Gear Seal and Noise Diagnostic

Bobcat·T86·Doosan D34·Advanced·2-4 hours·0 views
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The Bobcat T86 developed a harsh grinding or squealing noise in one of its final drive track motors during high travel speeds. Metal particles are found on the drain magnet, and gear oil is weeping onto the inner sprocket frame.

Symptoms

  • A metallic grinding noise from the sprocket hub assembly
  • Oil weeping down the inner face of the rubber track sprocket hub assembly
  • Excessive operating temperature on the final drive housing compared to the other side

Possible Causes

  • Leaking or worn high-pressure Duo-Cone face seal on the drive hub
  • Critically low planetary gear oil level inside the hub assembly
  • Chipped or broken planetary gear teeth or failed needle bearings

Diagnostic Procedure

  1. 1
    Conduct Visual Face Seal Examination
    Raise the loader track high off the ground. Clean off mud from behind the main sprocket mounting ring. Check for gear oil or thick fluid leaking from the seam between the stationary motor body and the rotating drive hub.
  2. 2
    Inspect Planetary Drain Oil for Debris
    Rotate the drive hub until one oil access plug is at the 12 o'clock position and the other is at the 6 o'clock position. Place an oil pan underneath, and slowly unscrew the lower plug. Check carefully for large metallic flakes or chunks on the magnetic drain plug, indicating planetary gear failure.
  3. 3
    Refill and Perform Oil Level Check
    Rotate the hub so the plugs are aligned horizontally at the 3 and 9 o'clock positions. Slowly fill the hub with gear oil until it just level with the bottom edge of the fill hole. If internal capacity was low, monitor for subsequent oil loss on test drives.
  4. 4
    Evaluate Spindle Bearing Run-Out
    Place a dial indicator tip on the outer edge of the track sprocket. Use a pry bar to apply upward pressure on the track assembly. If run-out or lateral movement exceeds the manufacturer's specification, rebuild the primary hub bearings.

Common Repairs

  • Replacing the drive hub Duo-cone oil seal kit
  • Overhauling planetary gear components and bearings
  • Replacing the final drive hub/planetary assembly

Safety Precautions

  • Support the machine on heavy-duty undercarriage stands to prevent slipping.
  • Allow components to cool down before opening the planetary hub plugs; oil inside may be hot and under pressure.

Required Tools

  • Heavy-duty dial indicator indicator kit
  • Hex wrench socket set
  • Oil collection pan

Related Fault Codes

N/A (Mechanical wear pattern)

People Also Ask

  • How do I check the oil level in a Bobcat T86 final drive planetary?
  • What causes a metallic grinding noise in a compact track loader sprocket hub?
  • How do you replace the duo-cone floating seal on a Bobcat T86?
  • What is the normal operating temperature range for a Bobcat T86 track motor housing?
  • Why is gear oil leaking onto the inside of my rubber tracks?
  • How often should you change Bobcat T86 planetary gear oil?

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Suggested Follow-Up Guides

  • Bobcat T86 Duo-Cone Floating Seal Replacement Procedure
  • Step-by-Step Planetary Gear Carrier Rebuild for Bobcat T86
  • Bobcat T86 Final Drive Oil Flushing and Maintenance Guide
  • How to Measure and Diagnose CTL Hydrostatic Motor Case Drain Pressure
  • Bobcat T86 Drive Sprocket and Track Tensioner Alignment Guide

Topics

Bobcat T86 final drive leaking oilcompact track loader planetary gear noiseBobcat T86 track motor rebuildDoosan D34 final drive diagnosticBobcat sprocket hub seal replacementtrack loader metallic grinding noise sprocketBobcat T86 duo cone seal leakfinal drive gear oil overheating BobcatBobcat T86 planetary gear wear patternCTL final drive lifetime seal failureBobcat track motor troubleshooting

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This educational guide was curated by FieldTech to help technicians diagnose common failures. Always follow manufacturer service manuals and safety procedures.