Replacing the Track Adjuster Stud on a CAT D4D 58J

[MikePhua]

The CAT D4D and Its Undercarriage Legacy
The Caterpillar D4D crawler tractor, particularly the 58J serial prefix, represents a transitional generation in CAT’s dozer lineup. Produced during the 1970s and early 1980s, the D4D was designed for mid-range grading, land clearing, and agricultural work. With an operating weight around 10 tons and a 4-cylinder diesel engine delivering roughly 80 horsepower, the D4D was known for its mechanical simplicity and rugged undercarriage.
The 58J series incorporated both screw-type and hydraulic-type track adjusters depending on configuration and market. These adjusters maintain track tension by pushing the front idler forward, absorbing recoil through a spring assembly. Over time, corrosion, wear, and misidentification of parts complicate maintenance—especially when parts books show outdated or mismatched diagrams.
Identifying the Correct Stud for the Spring Assembly
One of the most confusing aspects of maintaining the D4D’s recoil spring assembly is identifying the correct stud or bolt used in the hydraulic-type adjuster. The screw-type system uses part number 9H7537, but this does not directly translate to the hydraulic configuration found on many 58J machines.
Replacement parts are often cross-referenced as follows:

• 9H7537 → superseded by 9K5053 and 1B4334 in some catalogs
  
• 9K5446 → confirmed as the correct bolt for hydraulic recoil spring assemblies on similar models like the 82J
  
• 6H7768 → spacer used in the spring group, sometimes welded in place and not always necessary for replacement
  

The confusion arises because parts books may only show the screw-type adjuster, while the machine in question uses the hydraulic type. This discrepancy can lead to incorrect orders and long delays, especially for international owners.
Terminology and Component Breakdown
- Recoil Spring Assembly: A group of components that absorb track tension and allow for controlled movement of the front idler.
- Stud or Bolt: The central fastener that secures the spring assembly and interfaces with the adjuster mechanism.
- Hydraulic Track Adjuster: Uses hydraulic pressure to extend the front idler, maintaining track tension dynamically.
- Screw-Type Adjuster: Uses a threaded rod and nut to manually set track tension.
- Spacer: A cylindrical component that maintains alignment and preload in the spring group.
Field Diagnosis and Practical Considerations
In one case, the bolt pattern on the original stud was completely corroded away, making identification impossible without a parts diagram. The owner received a quote for 9H7537 but was unsure if it matched the hydraulic setup. After consulting diagrams from similar machines (e.g., 82J), it was determined that 9K5446 was the correct bolt.
The recoil spring was still under tension, and the spacer was welded in place—adding complexity to disassembly. Handling spring-loaded components requires caution, as stored energy can release violently if not properly restrained. One technician described treating the assembly “like a nuclear bomb,” underscoring the risk involved.
Recommendations for Safe Replacement and Sourcing
To replace the stud in a hydraulic recoil spring assembly:

• Confirm the adjuster type by inspecting the front idler mechanism
  
• Use diagrams from similar serial prefixes (e.g., 82J) if the 58J manual is incomplete
  
• Order 9K5446 for hydraulic setups, along with 1B4334 hex nut
  
• Consider replacing the spacer only if damaged or missing; otherwise, reuse
  
• Use aftermarket suppliers for cost savings, but verify part dimensions and thread pitch
  

Prices vary widely:

• CAT dealer price for 9K5446: ~$100
  
• Aftermarket price: ~$38–$42
  
• Spacer 6H7768: ~$81–$110 depending on source
  

Some suppliers require account setup to access discounted pricing. Others ship from U.S. warehouses to international locations, with delivery times ranging from 10 to 14 days.
Anecdotes and Sourcing Tips
One operator in Iceland sourced parts from a Boston-based supplier offering competitive pricing. He noted that while the parts warehouse wasn’t equipped to advise on compatibility, they fulfilled orders reliably when given correct part numbers.
Another technician in California confirmed that 9K5446 was used across multiple hydraulic recoil assemblies and remained available without supersession. He recommended checking with Regal or Offroad Equipment for vintage CAT parts, especially when dealer support is limited.
Conclusion
Replacing the recoil spring stud on a CAT D4D 58J requires careful identification of the adjuster type and cross-referencing part numbers. While the screw-type system is well-documented, hydraulic configurations demand extra diligence. With the correct bolt—typically 9K5446—and attention to spring tension and spacer alignment, the repair can be completed safely and economically. In vintage dozers, the right part is more than a number—it’s the key to keeping a classic machine moving forward.