Fixing Swing Slop in the Ford 4500 Backhoe

[MikePhua]

The Ford 4500 and Its Swing Mechanism Design
The Ford 4500 backhoe loader, introduced in the late 1960s and produced through the 1970s, was part of Ford’s industrial tractor lineup aimed at utility contractors, municipalities, and farmers. Built on a rugged platform with a torque converter transmission and mechanical shuttle, the 4500 featured a twin-cylinder swing system for backhoe articulation. Unlike modern gear-driven swing motors, the 4500 relied on hydraulic cylinders mounted laterally to push and pull the boom side to side.
This design, while simple and effective, is prone to developing swing slop over time due to wear in pivot pins, bushings, cylinder mounts, and the swing frame itself. Slop in the swing system reduces digging precision, causes bucket drift, and can lead to structural damage if left unchecked.
Identifying the Sources of Swing Slop
Swing slop typically manifests as excessive lateral movement of the boom when stationary or during digging cycles. Common causes include:

• Worn pivot pins between the boom and swing frame
  
• Elongated bushing bores in the swing tower
  
• Loose or damaged cylinder mounts
  
• Bent or fatigued swing frame brackets
  
• Hydraulic cylinder drift due to internal leakage
  

To diagnose:

• Park the machine on level ground and raise the boom
  
• Apply lateral pressure manually or with a pry bar
  
• Observe movement at each pivot point and cylinder mount
  
• Measure pin play with feeler gauges or calipers
  
• Check for hydraulic creep by watching boom movement over time without input
  

A contractor in Arkansas once discovered that his swing slop was caused by a cracked weld on the left cylinder bracket. The bracket flexed under load, exaggerating the slop even though the pins were tight.
Pin and Bushing Wear and Replacement Strategy
The swing pivot pins are subject to constant stress and contamination. Over time, they wear down and the bushings oval out. To restore tightness:

• Remove the boom from the swing frame using a crane or loader arms
  
• Press out old bushings and inspect bores for distortion
  
• Line bore if necessary to restore concentricity
  
• Install new bushings using freeze-fit or press-in method
  
• Replace pins with hardened steel replacements, preferably with grease grooves
  
• Torque retaining bolts to spec and recheck after 10 hours of operation
  

If the bores are too damaged for standard bushings, oversized bushings or weld-in sleeves may be required. Always match bushing material to pin hardness to prevent accelerated wear.
Cylinder Mount Integrity and Hydraulic Drift
Swing cylinders must be securely mounted and free of internal leakage. Key checks include:

• Inspect cylinder rod ends and clevis pins for wear
  
• Check mounting brackets for cracks or elongation
  
• Test for hydraulic drift by extending the boom fully and observing movement over 15 minutes
  
• Rebuild cylinders if drift exceeds 1 inch or if seals are visibly leaking
  

Cylinder rebuild kits are available and typically include rod seals, piston seals, wipers, and backup rings. A technician in Ontario rebuilt both swing cylinders on a 4500 and eliminated 80% of the swing slop without replacing any pins.
Frame and Structural Considerations
The swing frame itself can fatigue over decades of use. Look for:

• Cracks near welds or high-stress areas
  
• Bent brackets or misaligned mounts
  
• Weld repairs that have failed or were poorly executed
  
• Frame twist causing uneven boom movement
  

If the frame is compromised, reinforcement plates or full replacement may be necessary. Welding should be done with proper preheat and post-weld cooling to avoid warping.
Lubrication and Preventive Maintenance
To prevent future slop:

• Grease all swing pivot points weekly during active use
  
• Use high-pressure moly-based grease for heavy-duty applications
  
• Install sealed bushings where possible to reduce contamination
  
• Inspect pins and mounts monthly for signs of wear
  
• Avoid side-loading the boom during digging or swinging
  

Operators should be trained to swing smoothly and avoid abrupt stops, which stress the swing system and accelerate wear.
A Story from the Field
In 2020, a rural excavation crew in Georgia noticed their Ford 4500 had developed severe swing slop, making trenching difficult. After inspecting the swing tower, they found both bushings were worn through and the left cylinder bracket had cracked. Using a portable press and a MIG welder, they replaced the bushings and reinforced the bracket with a gusset. The repair cost under $300 and restored full swing control. The crew added weekly greasing and visual checks to their maintenance routine.
Conclusion
Swing slop in the Ford 4500 is a solvable problem rooted in mechanical wear and hydraulic fatigue. By inspecting pins, bushings, cylinder mounts, and frame integrity, operators can restore precision and prevent further damage. In legacy machines like the 4500, tight swing control is not just about performance—it’s about preserving the iron for the next generation of work.