Stihl 029 Farm Boss Clutch (Replacement Guide)
To replace the clutch on a STIHL 029 Farm Boss, first confirm the saw’s exact model and matching parts. Work with the engine cold, remove the bar and chain, and release the chain brake before removing the clutch drum. The clutch has a left-hand thread, so turn it clockwise to loosen. Reassemble with matched parts, then check chain movement, oil delivery, and brake function.
A chain saw that will not cooperate can turn a quick repair into an all-day argument. If the 029 is already on your bench, the aim here is simple: replace only what is worn, avoid damaging the crankshaft or brake, and confirm the saw is safe before cutting.
The clutch is not the same part as the clutch drum. The clutch shoes and springs engage the drum as engine speed rises; the drum turns the sprocket, which drives the chain. Damage or a mismatch in this group can cause poor drive, chain binding, or a chain that will not run correctly.
Confirm the parts and prepare the saw
This first check helps prevent a common repair mistake: ordering a clutch or drum that looks right but does not match the saw. Confirm the model and serial information, then check the correct parts diagram and the installed bar and chain before taking anything apart.
The 029 and 029 Super may use different parts or configurations. Do not rely on the model name alone to choose the clutch, drum, washer, oil-pump drive, or sprocket. Use the saw’s parts information to identify the correct combination.
| Item to check | What to verify | Why it matters |
|---|---|---|
| Saw identification | Model and serial information | Parts can vary by configuration |
| Clutch and drum | Correct parts for that saw | Parts must fit and work together |
| Sprocket pitch | Match the bar and chain markings or parts specification | A pitch mismatch can bind or derail the chain |
| Drum and oil-pump drive | Correct type and order | The drive must turn the oil pump as designed |
| Retainers and washers | Correct parts and assembly order | Missing or misplaced parts can affect fit |
Pitch is the spacing of the chain drive links and matching sprocket teeth. Gauge is the thickness of the drive links, which must fit the bar groove. Check the installed bar and chain markings or the saw’s parts specification; do not guess based on appearance.
Before work, let the engine cool. Wear eye protection and cut-resistant gloves. Switch the ignition off, remove the spark-plug boot, and remove the bar and chain. Keep the saw stable on a bench. The chain brake may be engaged while handling the saw, but release it before trying to remove the clutch drum. Never force a drum past a brake band that is still gripping it.
A couple of engine specifications are useful during general service, but they do not set clutch fit or adjustment: STIHL specifies a 50:1 fuel mix when using its specified two-stroke oil, and the spark-plug gap is 0.5 mm (0.020 in). Use the correct service information for the exact saw.
Remove the clutch and inspect the drive parts
The clutch is threaded onto the crankshaft, and its thread turns opposite to a standard right-hand thread. Restrain the crankshaft with a suitable piston stop or the model-appropriate service method, then turn the clutch clockwise, viewed from the clutch side, to loosen it.
Remove the clutch drum and related parts in order, and lay them out so you can track their position. If the drum does not come free, stop and check that the chain brake is released and that you are using the correct removal method. Do not use an impact wrench, jam the flywheel with a screwdriver, or pry against the crankcase.
With the parts off, inspect the following:
- Clutch shoes and springs: Look for cracks, broken or stretched springs, and uneven or heavy wear.
- Drum and sprocket: Replace a drum that is scored, blued, cracked, or out of round. Inspect sprocket teeth for wear.
- Needle bearing: This bearing supports the drum. Check for damage and lubricate it as STIHL specifies.
- Oil-pump drive: Check the drive parts for wear or damage and confirm they match the saw’s parts diagram.
- Crankshaft threads: Clean them and look for damage before installing the replacement.
Keep grease and oil off the clutch shoes, springs, drum braking surface, and chain-brake band. Lubricant on those surfaces can interfere with clutch action or braking. If the clutch is damaged but the drum and drive parts remain sound, those parts may not need replacement; decide by inspection and the correct parts information, not by guesswork.
Install the replacement clutch and drum
A replacement clutch must match the saw’s configuration. Confirm its part number and the required washer, drum, sprocket, and oil-pump drive before fitting it. The clutch’s left-hand thread tightens counterclockwise, viewed from the clutch side.
- Check the parts order. Compare each part with the saw’s diagram and your removal notes. Do not leave out a washer or fit the oil-pump drive in the wrong position.
- Fit the clutch. Install the specified clutch using the correct method for the model. Avoid damaging the shoes or crankshaft threads.
- Tighten to the service specification. Use the applicable STIHL service information for the correct torque and method. Do not substitute a generic torque value; one is not safe to assume across configurations.
- Lubricate the needle bearing. Apply lubricant as specified, keeping it off the clutch and braking surfaces.
- Refit the matched drum and retainers. Make sure the sprocket pitch matches the chain and bar, and that the oil-pump drive is correctly positioned.
After fitting the drum, check that it turns freely with the chain brake released. If it binds, wobbles, or does not sit correctly, stop and recheck the parts order and compatibility. Do not try to solve a fit problem by forcing the assembly.
Reassemble and test safely
The clutch replacement is a bench repair, not a reason to run the saw with parts missing. Refit the bar, chain, side cover, and chain brake before starting. Set chain tension to the bar manufacturer’s specification. The chain should be correctly seated and should move by hand with the brake released, while remaining properly tensioned.
Start the saw outdoors in a clear area, following its normal starting procedure. Watch and listen at idle before applying throttle. Stop at once if the chain moves at idle, the clutch drags, the drum wobbles, or you hear abnormal noise from the clutch area. Check oil delivery and confirm that the chain brake works as intended.
| Test | Normal check | Stop and inspect if… |
|---|---|---|
| Drum rotation, engine off | Drum turns freely with brake released | It binds or wobbles |
| Idle | Chain remains still | Chain moves at idle |
| Oil delivery | Oil reaches the chain as expected | No oil delivery is evident |
| Chain brake | Brake engages and stops the chain as designed | Brake fails to work normally |
| Initial run | No unusual clutch-area noise | Dragging, rattling, or other abnormal noise occurs |
After the initial check, shut the saw down. Recheck chain tension and visible fasteners. Return to cutting only if the saw runs normally and its safety systems work. If any test fails, do not keep running it to “see if it clears up.” Recheck the installation or have the saw inspected.
Common replacement problems and useful checks
In a typical bench diagnosis, the symptom can point to more than one part. A chain that does not drive may involve the clutch, drum, sprocket, or oil-pump drive; replacing the clutch without inspecting those parts can leave the fault in place.
A wrong-pitch drum is a critical mismatch. The chain may not seat correctly, bind, or derail. Match the drum, bar, and chain by specification, then confirm correct tension and smooth hand rotation before starting. A part that looks similar is not proof that it fits.
If the clutch will not loosen, confirm the direction: turn clockwise from the clutch side. Verify that the crankshaft is restrained with the correct tool or service method. Do not switch to an impact wrench or jam the flywheel to gain leverage; either can damage engine parts.
If the drum will not come off, check the chain brake before applying force. A brake band locked around the drum can be damaged if you pull against it. Release the brake and follow the model-appropriate removal steps.
For future service, record the installed clutch and drum part numbers and the chain pitch. Clean the clutch cover and oil passages after repair, and handle fuel and oily waste according to local requirements. For storage, follow STIHL’s guidance for the fuel in use, and fit the chain guard before putting the saw away.
Frequently asked questions
These answers cover the main fit, removal, and safety points for a clutch replacement on an 029. Use the parts diagram and model-specific service information when parts or torque details are uncertain; they take priority over a generic procedure.
Which way do I turn the clutch to remove it?
Turn it clockwise, viewed from the clutch side. The clutch uses a left-hand thread.
Which way does the clutch tighten?
It tightens counterclockwise, viewed from the clutch side. Use the torque and method specified for the saw.
Can I use an impact wrench to remove the clutch?
No. Use a piston stop or the appropriate service method to restrain the crankshaft, and remove the clutch with the correct tool. Do not use impact force.
Can I reuse the clutch drum?
Only if it is compatible and inspection shows it is serviceable. Replace a drum that is scored, blued, cracked, or out of round.
How do I know the replacement drum has the right pitch?
Check the bar and chain markings or the saw’s parts specification. Match the drum sprocket, chain, and bar by specification, not by appearance.
Do I need to replace the clutch and drum together?
Not always. Inspect the shoes, springs, drum, sprocket, bearing, and oil-pump drive. Replace worn or damaged parts with the correct matched components.
Can I remove the drum while the chain brake is engaged?
No. Release the chain brake before attempting to remove the drum. Do not force a drum held by the brake band.
What torque should I use for the clutch?
Use the applicable STIHL service specification for the exact saw configuration. Do not substitute a generic torque value.
Should the chain move at idle after the repair?
No. Stop the saw if the chain moves at idle. Inspect the clutch and installation before using it.
What should I do if the drum binds after installation?
Stop and recheck part compatibility, the washer and drive-part order, and brake position. Do not run or force a binding assembly.
Can I run the engine before refitting the bar and chain?
No. Refit the matched drum, bar, chain, side cover, and chain brake before starting. Check operation outdoors, then shut down and recheck chain tension.
(This article was written by one of our staff writers, Robert Callahan. Visit our Meet the Team page.)
