Track Bounce After Roller Replacement on the Bobcat MT55

[MikePhua]

The Bobcat MT55 and Its Compact Track System
The Bobcat MT55 is a walk-behind mini track loader designed for tight-access jobs, landscaping, and light excavation. With an operating weight of around 2,500 pounds and a rated operating capacity of 550 pounds, the MT55 is powered by a Kubota diesel engine and features a hydrostatic drive system. Its compact track undercarriage allows for low ground pressure and excellent maneuverability on turf, gravel, and uneven terrain.
The track system consists of rubber tracks, drive sprockets, idlers, and multiple rollers that support the machine’s weight and guide the track path. When rollers are replaced, especially with aftermarket parts or mismatched components, unexpected behavior like bouncing or vibration can occur—often due to alignment, tension, or geometry inconsistencies.
Terminology Notes

• Carrier Rollers: The top rollers that support the upper portion of the track loop.
  
• Bottom Rollers: The lower rollers that bear the machine’s weight and guide the track along the frame.
  
• Track Tensioner: A spring or hydraulic mechanism that maintains proper track tightness.
  
• Pitch: The distance between track lugs or drive teeth, critical for sprocket engagement.
  

Why Bounce Happens After Roller and Track Replacement
Track bounce is typically caused by one or more of the following:

• Roller Diameter Mismatch: If new rollers are slightly larger or smaller than OEM spec, the track path becomes uneven, causing rhythmic bounce.
  
• Track Pitch Incompatibility: If the new track has a different pitch than the sprocket or roller spacing, it may ride unevenly or skip.
  
• Improper Tension: Over-tightened tracks can amplify vibration, while loose tracks may slap or jump over rollers.
  
• Roller Misalignment: If rollers are not centered or installed at the correct height, the track may ride high or low, creating a wave effect.
  
• Frame Wear or Deformation: Older machines may have worn track frames or bent roller mounts, which distort the track path.
  

A contractor in Alberta replaced all rollers and tracks on his MT55 with aftermarket parts. The machine began bouncing at walking speed, especially on hard surfaces. After measuring roller diameter and comparing pitch, he discovered the new rollers were 3 mm taller than OEM spec, causing the track to ride unevenly.
Inspection and Diagnostic Strategy
To isolate the cause:

• Measure roller diameter and compare to manufacturer specifications
  
• Check track pitch and lug spacing against sprocket teeth
  
• Inspect roller mounts for wear, cracks, or misalignment
  
• Verify track tension using the manufacturer’s recommended clearance (typically 1–1.5 inches of sag between rollers)
  
• Observe track movement at low speed on flat ground
  

A technician in Georgia used a laser level to check roller alignment and found that one side was 5 mm higher than the other due to a bent mount. Realigning the roller eliminated the bounce.
Solutions and Adjustments
To correct bounce:

• Replace rollers with OEM-spec components or match diameter precisely
  
• Confirm track pitch compatibility with sprockets and rollers
  
• Adjust track tension to factory spec using the tensioner bolt or grease fitting
  
• Shim or realign roller mounts if frame distortion is present
  
• Test machine on varied terrain to confirm resolution
  

Recommended upgrades:

• Install track tension gauge for precise adjustment
  
• Use polyurethane-coated rollers to reduce vibration
  
• Add wear pads or bushings to roller mounts for tighter fit
  

A landscaping crew in Maine added tension indicators to their MT55 fleet and reduced bounce-related complaints by 80% over one season.
Preventive Maintenance and Best Practices
To avoid future issues:

• Inspect rollers and track tension monthly
  
• Replace tracks and rollers as a matched set when possible
  
• Avoid aftermarket parts unless specs are verified
  
• Clean roller mounts and tensioner threads during service
  
• Monitor track wear and lug deformation
  

A contractor in Texas standardized roller replacements across his fleet using OEM kits and saw a 30% increase in track life and smoother operation.
Anecdote from the Field
In 2023, a small excavation firm in Pennsylvania replaced the tracks and rollers on their MT55 with a budget kit. The machine began bouncing violently on concrete. After checking specs, they found the track pitch was designed for a different model. Replacing the tracks with matched pitch units resolved the issue. The owner now keeps a spec sheet for every undercarriage component in the shop.
Conclusion
Track bounce after roller replacement on the Bobcat MT55 is often a symptom of mismatched geometry, tension errors, or alignment flaws. With careful measurement, spec verification, and methodical installation, the issue can be resolved and prevented. For operators who rely on smooth movement in tight spaces, the undercarriage is more than a support system—it’s the foundation of control. When every inch matters, bounce is not just a nuisance—it’s a signal worth investigating.