Restoring Bucket Pivot Bushings on a Bobcat 863 G-Series Loader

[MikePhua]

The Bobcat 863 and Its Loader Arm Design
The Bobcat 863 G-Series, introduced in the late 1990s, is a large-frame skid steer loader known for its robust hydraulic system, high lift capacity, and straightforward mechanical layout. With a rated operating capacity of 1,900 lbs and a turbocharged diesel engine producing over 70 horsepower, the 863 was widely adopted in construction, agriculture, and landscaping. One of its defining features is the straight pin and wear bushing configuration in the loader arms, which differs from the tapered pin design found in smaller Bobcat models.
This design places the wear bushing directly in the loader arm, allowing for easier replacement but also making the bore susceptible to rust and deformation over time—especially if grease channels become misaligned or blocked.
Terminology Annotation
- Wear Bushing: A replaceable sleeve that absorbs friction between the pivot pin and loader arm, protecting the base metal.
- Grease Channel: A machined groove that allows lubricant to flow from the pin’s internal passage into the bushing surface.
- JB Weld: A two-part epoxy commonly used to bond metal surfaces or fill gaps in worn mechanical components.
- Shrink Fit: A method of installing bushings by cooling them to contract the metal, allowing easier insertion into a tight bore.
- Oversize Bushing: A replacement part with a larger outer diameter, used when the original bore has worn beyond tolerance and must be re-machined.
Diagnosing Bushing Misalignment and Grease Failure
In one restoration case, a 1999 Bobcat 863 with under 1,300 hours exhibited a failure in the bottom right bucket pivot pin. Grease would not flow into the bushing, despite attempts using heat and penetrating oil. Upon inspection, the bushing had shifted outward by approximately 1/8", misaligning the grease channel and causing wear on the bobtach assembly. This misalignment led to difficulty in dropping the attachment plate and prompted a full replacement of both bushings, pins, and seals.
The failed bore showed rust pitting and uneven wear, raising concerns about whether the new bushing would seat tightly enough to function properly.
Removing and Preparing the Bore
The bushings were removed using a MIG welding technique—welding beads inside the bushing to shrink it and then hammering it out. This method is effective for seized bushings and avoids damaging the bore. Once removed, the bore was cleaned with wire brushes and sandpaper, though care was taken not to remove excessive material. Despite cleaning, one bore remained loose enough that a test bushing could be inserted by hand, suggesting loss of interference fit.
Installing New Bushings with Epoxy Assistance
To address the loose fit, JB Weld was used to secure the new bushing. The bore and bushing were degreased thoroughly, scored with a file to improve adhesion, and coated with epoxy before insertion. The bushing was chilled in a freezer to aid installation, though the temperature drop was minimal. For tighter fits, dry ice or liquid nitrogen is preferred, as they can shrink metal components by several thousandths of an inch.
On the better side, the bushing required hammering with a pipe and lump hammer, indicating a satisfactory fit. JB Weld was still applied as a precaution, especially since the previous bushing had shifted inward and displaced the seal.
Seal Orientation and Grease Flow Considerations
Seal placement is critical for proper grease retention and flow. The correct orientation involves inserting the seal with the metal rim facing inward, exposing the rubber taper to the outside. This allows grease to escape through the taper and lubricate the bushing surface. Misplaced seals can block grease flow or allow contaminants into the bore.
Concerns about epoxy blocking the outer grease groove were addressed by confirming that grease is delivered through the pin’s internal passage, not the outer groove. Therefore, epoxy in the groove does not impede lubrication.
Alternative Solutions and Oversize Options
If the bore is too worn for standard bushings, Bobcat offers an oversize bushing (part number 7109386) that requires machining the bore to 1.8715" ±0.0005". This solution restores proper fit and alignment but requires precision boring equipment. Some technicians also recommend knurling the bushing’s outer diameter or using Loctite 640 sleeve retainer for added grip.
Conclusion
Restoring bucket pivot bushings on a Bobcat 863 requires attention to bore condition, bushing fit, and seal placement. While JB Weld and shrink-fit techniques can salvage moderately worn bores, severely damaged sockets may require machining and oversize bushings. With careful preparation and proper installation, the loader arm can regain full functionality and grease flow, extending the life of the pivot assembly. For owners of aging Bobcat machines, these repairs offer a cost-effective alternative to full arm replacement and keep the machine productive in the field.