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Understanding the Rear Axle System
The International 4700 is a medium-duty truck widely used in vocational applications such as towing, delivery, and construction. Its rear axle assembly plays a critical role in transferring engine torque to the wheels while supporting the vehicle’s load. Most 4700 models feature a single drive axle, often equipped with air brakes, ten-lug hubs, and a differential gear ratio ranging from 4.10 to 4.88 depending on the intended use.
Terminology Notes
Operators have reported several recurring issues with the rear axle on the International 4700:
Maintenance and Repair Tips
A fleet operator in Wheat Ridge, Colorado replaced a rear axle assembly on a 2000 International 4700 due to a cracked housing and worn differential. The replacement unit, sourced from a salvage yard, featured a 4.44 gear ratio and air brakes. After installation, the truck showed improved torque response and reduced noise. The operator noted that matching the gear ratio to the transmission was critical to avoid driveline stress.
Historical Context and Design Evolution
The International 4700 was introduced in the mid-1990s as part of Navistar’s medium-duty lineup. Its rear axle design reflects a balance between durability and serviceability. Unlike tandem axle configurations found in heavier trucks, the 4700’s single axle setup simplifies maintenance and reduces weight.
In the early 2000s, Navistar began offering upgraded axles with ABS integration and improved sealing technology, reducing long-term maintenance costs. These changes were in response to increased demand for vocational trucks that could handle urban stop-and-go traffic without frequent downtime.
Sourcing Parts and Replacements
Replacement rear axle assemblies and components are available through various suppliers:
The rear axle of the International 4700 is more than just a mechanical link—it’s a cornerstone of the truck’s performance and reliability. Whether diagnosing a clunk, swapping a differential, or simply topping off gear oil, attention to detail pays dividends in uptime and safety. And as one seasoned operator put it, “If the rear end’s talking, it’s time to listen—before it starts shouting.”
The International 4700 is a medium-duty truck widely used in vocational applications such as towing, delivery, and construction. Its rear axle assembly plays a critical role in transferring engine torque to the wheels while supporting the vehicle’s load. Most 4700 models feature a single drive axle, often equipped with air brakes, ten-lug hubs, and a differential gear ratio ranging from 4.10 to 4.88 depending on the intended use.
Terminology Notes
- Differential Gear Ratio: The ratio between the driveshaft rotation and wheel rotation. A higher ratio (e.g., 4.88) provides more torque but less speed.
- Axle Assembly: Includes the axle housing, differential, axle shafts, and brake components.
- Ten-Lug Hub: A wheel hub with ten mounting studs, common in heavy-duty trucks.
- Air Brakes: A braking system powered by compressed air, standard in commercial vehicles.
Operators have reported several recurring issues with the rear axle on the International 4700:
- Excessive play or noise from the differential, often due to worn bearings or gear misalignment.
- Oil leaks around the axle seals, typically caused by aged gaskets or overfilled housings.
- Brake imbalance or dragging, especially in air brake systems with aging diaphragms or misadjusted slack adjusters.
- Axle shaft wear, leading to vibration or reduced torque transfer.
Maintenance and Repair Tips
- Check fluid levels regularly, using the fill plug on the differential housing. Use gear oil rated SAE 80W-90 or 85W-140 depending on climate.
- Inspect axle seals during routine brake service. Replace if any seepage is visible.
- Torque axle flange bolts to manufacturer specs—typically around 120–150 ft-lbs for 5/8" studs.
- Monitor brake chamber performance and replace any units showing signs of air leakage or slow response.
A fleet operator in Wheat Ridge, Colorado replaced a rear axle assembly on a 2000 International 4700 due to a cracked housing and worn differential. The replacement unit, sourced from a salvage yard, featured a 4.44 gear ratio and air brakes. After installation, the truck showed improved torque response and reduced noise. The operator noted that matching the gear ratio to the transmission was critical to avoid driveline stress.
Historical Context and Design Evolution
The International 4700 was introduced in the mid-1990s as part of Navistar’s medium-duty lineup. Its rear axle design reflects a balance between durability and serviceability. Unlike tandem axle configurations found in heavier trucks, the 4700’s single axle setup simplifies maintenance and reduces weight.
In the early 2000s, Navistar began offering upgraded axles with ABS integration and improved sealing technology, reducing long-term maintenance costs. These changes were in response to increased demand for vocational trucks that could handle urban stop-and-go traffic without frequent downtime.
Sourcing Parts and Replacements
Replacement rear axle assemblies and components are available through various suppliers:
- Used assemblies from salvage dealers, often priced between $1,000–$1,500 depending on condition.
- OEM studs and seals from Navistar parts distributors.
- Aftermarket upgrades, including reinforced axle shafts and synthetic gear oils, for fleets operating in extreme conditions.
The rear axle of the International 4700 is more than just a mechanical link—it’s a cornerstone of the truck’s performance and reliability. Whether diagnosing a clunk, swapping a differential, or simply topping off gear oil, attention to detail pays dividends in uptime and safety. And as one seasoned operator put it, “If the rear end’s talking, it’s time to listen—before it starts shouting.”
