Replace a mini excavator sprocket by securing the machine, removing the track and final drive cover, unbolting the worn sprocket, checking the final drive flange, and fitting and torquing the new sprocket before seating the track. The drive system is the focus: the final drive flange check and the sprocket-to-chain engagement decide the job's success.
Related reading: for segment-only maintenance, see our sprocket segment replacement guide.
Sprocket Installation Guidance from AFT Parts
- Source: AFT Parts — sprockets and undercarriage components.
- Scope: Mini excavator sprocket replacement and final drive check
- Fits: CAT, Komatsu, Kubota, Bobcat, Hitachi, Takeuchi, and more.
- Application coverage: Quebec utility work, landscaping, municipal fleets
- Verified: part number and machine serial before dispatch.
Tools and Safety Preparation Before the Drive Is Exposed
Gather lifting gear, a track bar, sockets, and the torque values for the sprocket bolts. Park on level ground, block the machine, and release track tension before working at the drive.
Never work under a tensioned track, and keep hands clear of the sprocket teeth while the track is being removed. The final drive area carries high forces even with the track released.
Confirm the sprocket part number and tooth count against the machine serial number before the job starts, so the new part is verified while the old one is still in place.
Removing the Track and Final Drive Cover Cleanly
Release the tensioner and remove or move the track clear of the sprocket. Remove the final drive cover as the machine requires to access the sprocket mounting.
Clean the area before unbolting so dirt does not enter the final drive. Photograph the sprocket and the mounting before removal for the part-number reference.
Support the track clear of the drive while the sprocket is off, so nothing rests against the exposed flange during the change.
Unbolting the Worn Sprocket Without Damaging the Hardware
Remove the sprocket bolts with the correct sockets, and lift the worn sprocket clear with proper equipment. Inspect the bolts for wear and the spline or mounting for damage.
Do not reuse damaged bolts. The sprocket carries the full drive torque, so the hardware is part of the specification.
Checking the Final Drive Flange: The Step That Saves the New Sprocket
Inspect the final drive flange for wear, pitting, or damage before fitting the new sprocket. A damaged flange will wear the new sprocket and can indicate a final drive problem.
Clean the flange face and confirm it is flat. If the flange shows damage, address it before the sprocket replacement, or the new part fails early.
With the drive exposed, check the final drive oil level and condition at the same time. Low or contaminated oil is a reason to stop and service the drive before the new sprocket goes on, because a failing drive wears the new sprocket regardless of the part quality.
Fitting and Torquing the New Sprocket to the Published Values
Confirm the part number and tooth count match the machine, fit the new sprocket onto the flange, and torque the bolts to the published values in the correct sequence.
Use a calibrated torque wrench and mark the bolts after the initial torque. A sprocket fitted with the wrong torque or sequence can loosen and damage the drive.
Fit the sprocket fully onto the spline or flange before any torque, so the part seats square and the bolts pull it evenly.
Seating the Track and Test Run: Forward, Reverse, and Re-Torque
Re-tension the track to the published sag range, rotate the track a full revolution, and check the engagement at the sprocket. Run the machine forward and reverse and listen at the drive.
Re-torque the sprocket bolts after the first hours of operation. A test run that shows slipping or noise means the pitch, tooth count, or tension is wrong.
The test run should include a loaded pass, not just idle rotation: the machine should track straight and turn without a skip at the drive. A sprocket that engages cleanly under load confirms the pitch, count, and tension together.
Safety note: sprocket service exposes the final drive — release track tension first, use the OEM service manual for your model, and have the work performed by qualified personnel.
Before Ordering
- Confirm the sprocket part number and tooth count against the machine serial number.
- Ask whether the kit includes new bolts and torque values.
- Plan the change around a maintenance stop, not a failure.
Conclusion
Mini excavator sprocket replacement is a drive-side job: secure the machine, inspect the final drive flange, fit and torque the new sprocket, and verify engagement before the machine returns to work. New hardware and a correct re-torque schedule protect the drive.
Key Takeaways for Canadian Operators
- Release track tension before working at the drive.
- Inspect the final drive flange before fitting the new sprocket.
- Use new hardware and torque by the book.
- Confirm pitch and tooth count match the chain.
Questions to Ask Before You Order
- What are the sprocket part numbers and tooth count for my machine?
- What torque values apply to the sprocket bolts?
- Does the sprocket include mounting hardware?
Browse the Sprocket collection and the 207-27-33222 Komatsu sprocket for your machine.
Frequently Asked Questions
Do I need to remove the track to replace a sprocket?
Yes, the track must be released and moved clear of the sprocket, and the final drive cover removed as the machine requires. Release tension first.
Can I reuse the sprocket bolts?
No. Use new hardware at the specified grade. The sprocket carries full drive torque, so reused or damaged bolts loosen and fail.
Why should I check the final drive flange?
A worn or damaged flange wears the new sprocket and can indicate a final drive problem. Inspect and clean it before fitting the new part.
Do I need a special puller for the sprocket?
Some final drives need a puller; others release with the mounting bolts. Follow the OEM service manual for your model.
Should the final drive oil be checked during sprocket replacement?
Yes. With the drive exposed, check the oil level and condition — a low or contaminated drive is a reason to stop.