Overview
This aftermarket clutch drum and sprocket kit serves as a direct replacement for the factory unit on your chainsaw. The clutch drum and sprocket kit houses the sprocket that drives the chain and absorbs engagement forces from the clutch, so when the sprocket teeth wear down and the drum bore enlarges from heat and friction, cutting performance and safety both suffer. Swapping in a fresh replacement restores reliable chain drive and helps protect the rest of the drivetrain.
Key specifications
- Pitch: 3/8”
- Teeth: 7T
- Material: hardened steel
- Type: aftermarket replacement
Compatibility
Built to fit Stihl MS391 MS311 Replacement Parts with Needle Bearing and other models sharing the same drivetrain layout. Always confirm your specific model and year against the compatibility list, because sprocket dimensions can differ even between closely related saws.
Installation notes
Remove the clutch cover, bar, and chain. Lock the piston with a stop tool and unthread the clutch (left-hand thread on most saws). Swap the old drum and sprocket for the new kit, making sure the needle bearing is seated properly. Reinstall the clutch, cover, bar, and chain. Adjust chain tension and let the saw idle briefly to confirm smooth sprocket rotation.
Common questions
Q: Will this 3/8” 7-tooth spur clutch drum kit fit my Stihl MS311, or is it only for the MS391?
Yes, this kit is made for both the Stihl MS311 and MS391 clutch setup. As long as your saw uses a 3/8” pitch setup and the original clutch drum style matches the 7-tooth spur drum, this replacement should fit correctly with the included needle bearing, washer, and E-clip.
Q: Does this kit include everything I need to replace a worn clutch drum on my MS391?
It includes the clutch drum sprocket, needle bearing, clutch washer, and E-clip, which are the common wear parts for this repair. You should still inspect the clutch shoes and crankshaft stub for scoring or heat damage before installation, because badly worn clutch parts can quickly damage a new drum.
Q: How do I know when the 7T spur drum bearing on my Stihl MS391 needs to be replaced, and should I grease it during installation?
If the drum has side-to-side wobble, makes grinding noises, or shows blue discoloration from heat, the needle bearing should be replaced along with the drum. Lightly grease the new bearing during installation and keep the area clean, since dry or dirty bearings are a common cause of premature clutch drum wear.
