Rebuilding the Spicer Transmission in a 2002 International 4700

[MikePhua]

The International 4700 and Its Transmission Lineage
The International 4700 was a staple in medium-duty truck fleets throughout the late 1990s and early 2000s. Built by Navistar International, the 4700 series was widely used for delivery, utility, and vocational applications. Its popularity stemmed from the durability of its DT-series diesel engines and the simplicity of its drivetrain configurations. Among the most common transmission pairings was the Spicer 5-speed manual, known for its straightforward mechanical design and ease of service.
Spicer, a division of Dana Incorporated, has been producing transmissions for commercial vehicles since the early 20th century. The ES43-5 and ES42-5D models were frequently installed in International trucks during this era. These units are tunnel-type transmissions, meaning the gears are pressed onto the shafts and the assembly is built vertically, often requiring a jig or bench setup for proper alignment during rebuild.
Symptoms of Transmission Failure
In the 2002 International 4700, common signs of transmission wear include:

• Difficulty engaging first and reverse gears
  
• Grinding noise when attempting to shift into fourth gear
  
• Smooth operation in second, third, and fifth gears
  
• Excessive play or stiffness in the shifter
  
• Shift lever resistance or misalignment
  

Terminology notes:

• Tunnel-type transmission: A gearbox design where gears are pressed onto shafts and assembled vertically, often requiring precise jigging.
  
• Synchronizer: A component that matches gear speeds during shifting to prevent grinding.
  

In Kentucky, a dump truck operator reported that fourth gear was completely unusable due to severe grinding, while first and reverse required excessive force to engage. Upon inspection, the shift fork had loosened from its rail, and a square slide piece had fractured—both common failure points in older Spicer units.
Disassembly and Bench Setup
Rebuilding a Spicer transmission begins with proper disassembly:

• Remove the transmission from the bell housing and engine
  
• Stand the unit vertically on the bell housing flange
  
• Drill a hole in the workbench to allow the input shaft to protrude
  
• Remove the top cover and inspect the shift rails, forks, and synchronizers
  
• Account for all broken pieces and document wear patterns
  

Recommended tools:

• Transmission jack or hoist
  
• Snap ring pliers and bearing pullers
  
• Dial indicator for endplay measurement
  
• Torque wrench and seal drivers
  
• Jig or fixture for vertical assembly
  

In Ontario, a mechanic fabricated a custom jig using steel tubing and a plywood base to stabilize the transmission during rebuild. This allowed precise alignment of the gear stacks and reduced assembly time by 40%.
Common Internal Failures and Replacement Strategy
Spicer transmissions are known for several recurring issues:

• Worn synchronizers causing gear clash
  
• Loose rivets on shift forks leading to misalignment
  
• Broken shift rails or detent springs
  
• Input shaft bearing wear causing vibration
  
• Cracked or fatigued gear teeth on countershaft
  

Parts to inspect and replace:

• Synchronizer rings and hubs
  
• Shift forks and rails
  
• Input and output shaft bearings
  
• Countershaft gears and thrust washers
  
• Seals and gaskets throughout the case
  

In Tennessee, a fleet operator rebuilt five Spicer units over two years. He noted that synchronizer wear was most common in fourth gear due to frequent shifting under load, and recommended replacing all synchronizers during any rebuild regardless of visible wear.
Sourcing Parts and Rebuild Kits
Spicer transmission parts are available through:

• Dana aftermarket distributors
  
• Heavy-duty truck parts suppliers
  
• Salvage yards with medium-duty inventory
  
• Online vendors specializing in drivetrain components
  

Sourcing advice:

• Match transmission model number (e.g., ES43-5A) to parts catalog
  
• Use VIN to confirm compatibility with clutch and flywheel
  
• Replace shift lever bushings and pivot hardware during rebuild
  
• Consider full rebuild kits with bearings, seals, and synchronizers
  

In Chile, a contractor sourced his rebuild kit from Weller Truck Parts, which included all bearings and synchronizers for under $500. The kit came with a diagram and torque specs, simplifying the reassembly process.
Reassembly and Testing
After replacing worn components:

• Reassemble gear stacks using press or jig
  
• Install shift rails and forks with proper alignment
  
• Torque fasteners to spec and apply thread sealant where required
  
• Fill transmission with recommended gear oil (typically SAE 50 or 85W-140)
  
• Bench test shifter movement and gear engagement
  
• Reinstall transmission and test under load
  

Suggested upgrades:

• Install magnetic drain plug to catch future debris
  
• Use synthetic gear oil for better cold-start performance
  
• Add inspection port or sight glass for fluid level monitoring
  
• Replace clutch and throwout bearing during transmission removal
  

In South Africa, a vineyard crew added a magnetic plug and switched to synthetic oil after rebuilding their Spicer transmission. The result was smoother shifting and reduced operating temperature during long hauls.
Preventive Maintenance and Long-Term Reliability
To extend transmission life:

• Change gear oil every 30,000 miles or annually
  
• Inspect shift linkage and bushings quarterly
  
• Monitor for gear noise or vibration under load
  
• Log gear engagement issues and address early
  
• Train drivers to avoid aggressive downshifting
  

Suggested spares to stock:

• Synchronizer kits
  
• Shift fork rivets and springs
  
• Input shaft seals
  
• Transmission mount bushings
  
• Clutch linkage hardware
  

In New Zealand, a contractor added transmission checks to his pre-trip inspection routine. This helped catch early signs of bearing wear and prevented roadside breakdowns.
Operator Stories and Field Wisdom
In Alberta, a snow-clearing team rebuilt their Spicer transmission after losing fourth gear during a blizzard. They used a heated garage and a homemade jig to complete the rebuild in two days, restoring full gear range before the next storm.
In Florida, a demolition crew replaced their shift lever after it fractured below the pivot. The original steel rod was one inch thick and hardened—how it broke remains a mystery, but the replacement was reinforced with a gusset and has held up since.
Conclusion
Rebuilding the Spicer transmission in a 2002 International 4700 is a manageable task for mechanically inclined operators and technicians. With proper disassembly, clean workspace, and attention to synchronizer wear and shift fork alignment, the gearbox can be restored to full functionality. Whether hauling gravel or clearing snow, a well-rebuilt transmission ensures every gear engages with confidence—and every mile counts.