C5-2 Feed Trimmer Head - Fits Stihl FS38, FS40, FS45, FS46 - Replaces 4006-710-2106, 4006-710-2103

AutoCut C5-2 Trimmer Head for Stihl Curved Shaft Trimmers

Key Features

• AutoCut "C" Series Easy-Loading: Features a specialized internal spool that allows for reloading trimmer line without disassembling the head; simply insert the line and twist the knob to wind.
• Dual-Line Bump Feed: Engineered for reliable line advancement with a single tap on the ground during full-throttle operation, maintaining a consistent cutting swath.
• High-Impact Polymer Construction: Manufactured from glass-reinforced nylon to withstand high-velocity contact with rocks, curbs, and fence posts.
• Low-Profile Aerodynamic Design: Designed to reduce air resistance and engine drag, allowing small-displacement trimmers to maintain higher RPMs for cleaner cuts.
• Precision-Balanced Spool: Reduced vibration during high-speed rotation, which protects the trimmer's flexible drive shaft and reduces operator hand fatigue.

Replaces / Cross-Reference Part Numbers

• 4006 710 2106
• 4006 710 2103
  
• AutoCut C5-2

Compatibility & Fitment

This trimmer head is specifically designed for Stihl's lightweight curved-shaft trimmers and electric models. Key compatible models include:

• Stihl Gas Trimmers: FS 38, FS 40, FS 45, FS 45 C, FS 46, FS 50, FS 50 C.
• Stihl Electric Trimmers: FSE 60, FSE 71, FSE 81.
• Stihl KombiSystems: FS-KM (Curved shaft attachment).
• Note: Not compatible with straight-shaft Stihl trimmers (FS 55, FS 56, etc.) which typically utilize the larger C26-2 head with different arbor threads.

When to Replace

• Worn-Through Bump Cap: The bottom of the head is ground down to the point where the internal spring is visible or the line release no longer functions.
• Cracked Housing: Visible stress fractures in the black outer shell, which can lead to the head shattering at high RPM.
• Line Won't Load: The internal "eyelets" no longer line up or the winding mechanism is jammed with dried sap and debris.
• Eyelet Failure: The metal line exits have fallen out or are deeply grooved, causing the trimmer line to snap off inside the head repeatedly.
• Excessive Vibration: The head has become unbalanced due to uneven wear, putting unnecessary stress on the trimmer's motor and drive cable.

Installation Tips

• Left-Hand Threads: Remember, this head is Left-Hand Threaded. To tighten it onto the trimmer, you must turn it Counter-Clockwise.
• Easy-Load Alignment: To reload, rotate the top knob until the arrows on the knob align with the metal eyelets. Push about 10–13 feet of 0.080" line through until it is even on both sides, then twist the knob to wind it in.
• Line Diameter: For best results on FS 38/45 models, use 0.080" (2.0mm) line. While 0.095" may fit, it can cause the small engine to bog down and overheat the clutch.
• Clean the Head: Every time you reload the line, tap out any accumulated grass and dirt from inside the head to ensure the "bump" action stays smooth.
• Drive Cable Care: While the head is removed, check the end of your drive cable. If it looks dry, apply a small amount of Stihl Multilub to prevent the cable from snapping inside the shaft.