Track Wear and Repair Decisions for Mitsubishi BS3F Dozers

[MikePhua]

The Mitsubishi BS3F and Its Track System
The Mitsubishi BS3F crawler dozer is a compact earthmoving machine designed for agricultural and light construction use. Manufactured by Mitsubishi Heavy Industries, a company with roots dating back to 1884 and a long history in industrial machinery, the BS3F was part of a series of small dozers that gained popularity in Asia and rural North America during the 1980s and 1990s. Though exact production numbers are limited, the BS series was widely adopted for farm grading, pond excavation, and forestry trail maintenance.
The undercarriage of the BS3F consists of a conventional track system: track chains, bushings, pins, sprockets, rollers, and idlers. The track chain is a loop of steel links connected by pins and bushings, which rotate around the sprockets and rollers as the machine moves. Over time, wear occurs due to friction, terrain impact, and improper tensioning.
Identifying Track Wear Symptoms
Operators often notice unusual wear patterns on bushings and sprocket teeth, especially when tracks have been run loose for extended periods. Loose tracks allow excessive movement between components, accelerating wear and misalignment. Common symptoms include:

• Bushing ovality or flattening
  
• Sprocket teeth thinning or hooking
  
• Pin bosses contacting roller flanges
  
• Chain slack that allows manual movement by hand
  

These signs indicate that the track assembly is nearing the end of its service life or requires corrective maintenance.
Evaluating Repair Options
When faced with worn tracks, operators must decide between three main options:

• Tighten and Continue Running
  This is the lowest-cost option and may be acceptable for light-duty farm use. However, loose or worn tracks are prone to derailment, especially on uneven terrain. If the machine is used for grading or pulling loads, the risk of track loss increases.
  
• Repin and Re-bush the Chains
  This involves pressing out the old pins and bushings and installing new ones. It restores the chain’s geometry and reduces internal play. However, the process requires specialized hydraulic presses and skilled labor. For older machines like the BS3F, sourcing compatible kits may be difficult, and the cost of labor can exceed the value of the machine.
  
• Replace the Track Chains Entirely
  New chains offer restored link height, fresh bushings, and correct pitch. Prices vary, but estimates suggest around $750–$900 per chain, plus $150 for bolts and nuts. This option ensures long-term reliability and is often more cost-effective than rebuilding, especially when sprockets and rollers also need replacement.
  

Measuring Wear and Making Decisions
To assess track wear quantitatively, measure the pitch—the distance between pin centers—and compare it to factory specifications. Excessive elongation (typically beyond 75% of allowable wear) indicates the need for replacement. Additionally, check the link height. A new BS3F chain has a link height of approximately 2.95 inches (75 mm). If the height has dropped significantly, the rollers may begin contacting the pin bosses, causing further damage.
Roller wear also plays a role. Bottom rollers that have worn down on their outer diameter can allow the chain to sag, increasing the chance of derailment. Replacement rollers cost around $98 each and should be considered when replacing chains.
A Story from the Field
A farmer in Hartwell, Georgia shared his experience with a BS3F used for pond maintenance and trail clearing. After noticing the tracks were loose and the bushings had unusual wear, he debated between tightening the tracks or investing in new chains. Running a machine shop, he had the capability to rework sprockets but found that sourcing pin and bushing kits was difficult and expensive.
Eventually, he opted for new chains and refurbished the sprockets in-house. The machine returned to service with improved traction and reduced derailment risk. He noted that while the upfront cost was higher, the long-term reliability justified the investment, especially for seasonal work where downtime could delay critical tasks.
Recommendations for Track Maintenance
To extend the life of track components and avoid premature failure:

• Maintain Proper Tension
  Adjust track tension regularly based on terrain and usage. Loose tracks accelerate wear; overly tight tracks increase stress on components.
  
• Inspect Link Height and Pitch
  Use calipers or a measuring tape to monitor wear. Record values during each service interval.
  
• Replace Components in Sets
  When replacing chains, consider replacing sprockets and rollers simultaneously to ensure compatibility and prevent uneven wear.
  
• Use Quality Lubricants
  Grease and oil used in track pins and bushings should meet OEM specifications. Contaminated or low-grade lubricants accelerate internal wear.
  
• Store Equipment Properly
  When not in use, park the machine on level ground and avoid prolonged exposure to moisture, which can corrode track components.
  

Conclusion
The Mitsubishi BS3F remains a capable machine for farm and light construction use, but its track system demands careful attention as it ages. Operators must weigh the cost of repairs against the value of the machine and the demands of the work. Whether tightening, rebuilding, or replacing, informed decisions backed by measurement and experience will keep the dozer productive and safe. In the world of iron, a well-maintained track system is the foundation of every successful push.