CAT 304 Drive Sprocket Discussion and Guidance

[MikePhua]

Situation Overview
A 304C CR mini‑excavator owner shared that, after about 3,000 hours, they’re preparing to put on a new track set. Naturally, they’re wondering whether to replace the drive sprockets, specifically the OEM part 158‑4795, at the same time. They also questioned whether OEM sprockets are meaningfully better than aftermarket alternatives—and noted that their parts quote included new washers for the sprocket bolts, but not the bolts themselves.
According to advice from a seasoned technician, the existing sprockets still have life left, and replacement may not be necessary if wear is minimal.
Here are the key technical, cost, and maintenance considerations, along with recommendations based on this case and best practices.

Technical Considerations

• Sprocket Wear vs. Track Life
  • At around 3,000 hours, a drive sprocket may or may not be significantly worn depending on operating conditions, track tension, and environment.
    
  • Replacing sprockets too early leads to unnecessary cost, while replacing too late can accelerate wear on new track shoes.
    
• Bolt and Washer Strategy
  • The sprocket in question uses 9 bolts.
    
  • The technician noted these particular bolts are not “torque-turn” (i.e., not single‑use stretch bolts), meaning they can, in theory, be reused if in good condition.
    
  • Washers were included possibly because they’re more likely to get crushed or distorted under load compared to the bolts themselves.
    
• OEM vs Aftermarket
  • OEM parts (like Caterpillar) often offer guaranteed fit, hardness, and quality—but typically at a higher price.
    
  • Aftermarket sprockets can be quite good if made from high‑quality steel and properly hardened. Choosing them requires careful sourcing.
    

Risks of Not Replacing Sprockets
If new tracks are fitted but old sprockets are retained:

1. Premature Track Wear
   • A worn sprocket tooth profile can “bite” new shoes incorrectly, reducing the life of the new tracks.
     
2. Noise and Vibration
   • Mismatched or worn sprocket geometry may cause increased track noise or vibration.
     
3. Bolt Fatigue
   • Reusing old fasteners without checking integrity may eventually lead to bolt fatigue or loosening under cyclical load.
     

When It May Be OK to Reuse Sprockets

• Sprocket teeth still have good profile, without rounding or chipping.
  
• Bolt condition is verified (no corrosion or stretch).
  
• The cost of new OEM sprockets outweighs perceived benefit and wear rates are moderate.
  
• Track replacement is not “life-of-machine” but scheduled maintenance.
  

Recommendations

• Perform a visual inspection of sprocket teeth for wear, pitting, or rounding.
  
• Check bolt condition: remove a few, inspect for stretch or fatigue, and torque-test at reassembly.
  
• If reusing bolts, replace washers (as was quoted) to ensure a good seat and avoid loosening.
  
• If buying new sprockets, consider both OEM and high-quality aftermarket options, based on cost and availability.
  

Replacement Options
Here are some reliable sprocket options for the 304 machine:

• CAT 304 Track Sprocket (304‑1916) – OEM‑spec, bolt-on, proven durability.
  
• CAT 304 Track Sprocket – 19‑tooth – Variant with a different tooth count for specific applications.
  
• ES SPROCKET SP140 for CAT 303/304 – Aftermarket, suitable for certain 304 series machines.
  
• CAT 304 E2 CR Replacement Sprocket (PN 264‑5371) – Designed for newer 304E2CR; check compatibility.
  

Undercarriage Maintenance Tips

• Regularly inspect track tension and adjust to spec to preserve sprocket and track life.
  
• Drain final-drive gear oil periodically: low or contaminated oil can lead to wear on the drive motor seals, which may affect sprocket function.
  
• Perform a daily undercarriage visual check, especially after working in abrasive or muddy environments, to catch early wear or damage.
  

Conclusion
Given the 3,000‑hour runtime, replacing the drive sprocket on the 304C CR is not strictly mandatory if the teeth show minimal wear and the bolts remain in good shape. That said, taking the opportunity to check, clean, and possibly replace bolts or washers while doing track work is smart. If the sprockets are borderline, investing in new OEM or reputable aftermarket ones offers long-term protection for the new tracks — reducing the risk of early track wear or undercarriage damage.