Caterpillar D8H 46A Series Identification Restoration and Scrap Evaluation

[MikePhua]

The Caterpillar D8H and Its Historical Significance
The Caterpillar D8H dozer, particularly the 46A series, was manufactured during the 1960s and early 1970s, marking a pivotal era in Caterpillar’s evolution of heavy crawler tractors. Known for its raw torque, mechanical reliability, and straightforward serviceability, the D8H became a staple in mining, forestry, and large-scale earthmoving. The 46A serial prefix identifies it as part of the early D8H production run, with units like 46A17084 dating to approximately 1968.
Terminology annotation:

• Bare Tractor Weight: The weight of the machine without blade, cab, or attachments—used for transport and valuation.
  
• Ring Gear and Pinion: A matched gear set in the differential or final drive that transmits torque from the transmission to the tracks.
  
• Serial Number Prefix: A code used by Caterpillar to identify model series and production year.
  
• Registration Number: Often a fleet or internal tracking number, not tied to Caterpillar’s manufacturing records.
  

In Montana, a retired contractor inherited a D8H with dual blades and a weathered serial plate. Though the machine hadn’t run in years, its frame and undercarriage remained intact—prompting a debate between restoration and scrapping.
Identifying Year and Weight from Serial Data
The serial number 46A17084 places the machine in the 1968 production year. Caterpillar’s records show that the 46A series began in the early 1960s and ran through the early 1970s, with incremental updates to hydraulics and drivetrain. The bare tractor weight of a D8H 46A is approximately 48,000 lbs, excluding blade, cab, and ripper.
Identification steps:

• Locate serial plate on left rear frame rail or engine block
  
• Cross-reference with Caterpillar serial number guide
  
• Confirm model year via engine casting codes or transmission tag
  
• Estimate total weight by adding blade (approx. 6,000 lbs) and cab (1,500 lbs)
  
• Use historical parts catalogs to verify configuration
  

Recommendations:

• Preserve serial plate and document all identification numbers
  
• Photograph casting codes and tag plates for archival
  
• Consult Caterpillar dealer or vintage equipment registry for confirmation
  
• Keep identification data for insurance and resale purposes
  

In Idaho, a collector restored a 1967 D8H using archived parts manuals and confirmed the build year through the transmission housing stamp.
Evaluating Restoration Potential vs Scrap Value
The decision to restore or scrap a vintage D8H depends on undercarriage condition, drivetrain integrity, and parts availability. While the ring gear and pinion replacement is a major job, many components remain accessible through aftermarket suppliers and salvage yards.
Restoration factors:

• Undercarriage wear—track pads, rollers, idlers
  
• Engine compression and oil condition
  
• Transmission engagement and clutch response
  
• Hydraulic cylinder seals and pump output
  
• Frame integrity and weld condition
  

Scrap value considerations:

• Steel weight at current market rate (approx. $0.10–$0.15/lb)
  
• Blade and ripper assemblies often sold separately
  
• Salvageable components—radiator, fuel tank, final drives
  
• Transport cost to scrap yard vs resale to collector
  

Recommendations:

• Perform oil sampling and compression test before teardown
  
• Inspect ring gear teeth and backlash with differential cover removed
  
• Evaluate cost of replacement parts vs resale value
  
• Contact vintage equipment buyers or museums before scrapping
  
• Document machine history and condition for potential buyers
  

In Oregon, a forestry crew sold a non-running D8H to a restoration enthusiast for twice its scrap value—primarily due to its complete blade assembly and original serial plate.
Ring Gear and Pinion Replacement Complexity
Replacing the ring gear and pinion in a D8H involves disassembling the rear differential housing, removing the final drives, and aligning the gear set with precise backlash and preload. It’s a labor-intensive process requiring heavy lifting equipment and mechanical expertise.
Replacement steps:

• Drain differential and remove rear cover
  
• Disconnect track frames and remove final drives
  
• Extract pinion shaft and ring gear carrier
  
• Install new gear set and adjust backlash to spec (typically 0.008–0.012 inch)
  
• Reassemble with new seals and gaskets
  
• Test under load for noise and vibration
  

Recommendations:

• Use OEM or matched aftermarket gear sets
  
• Replace carrier bearings and seals during rebuild
  
• Torque all fasteners to Caterpillar spec
  
• Monitor gear temperature and wear during break-in
  
• Keep detailed service log and part numbers
  

In Nevada, a mining operator rebuilt the rear end of a D8H using a donor gear set from a retired unit. The machine returned to service pushing overburden with no further drivetrain issues.
Conclusion
The Caterpillar D8H 46A series remains a symbol of mechanical endurance and industrial heritage. While the ring gear and pinion replacement is a significant undertaking, the machine’s value lies in its undercarriage, blade assemblies, and historical identity. Whether restored for work or preserved for legacy, the D8H continues to represent a time when torque was king and steel told the story. In the world of vintage iron, every serial number carries weight—and every gear speaks of power, precision, and perseverance.