Lawn Mower Trimmer Gear Box Head Cutter Strimmer Grass Replacement for Stihl FS36 FS40 FS44 FS55 FS72 FS74 FS75 FS76 Weed Eater

Key Features

• High-Grade Aluminum Alloy Construction: The gearbox housing is manufactured from premium aluminum alloy, offering excellent thermal dissipation, corrosion resistance, and lightweight durability for reduced operator fatigue.

• Smooth Power Transfer: Features precision-engineered internal gears designed to deliver high torque and consistent RPM transfer from the drive shaft to the cutting head under heavy landscaping loads.

• Complete Replacement Combo: Includes both the heavy-duty gear case and a matching trimmer head, allowing you to completely refresh your equipment’s lower drive system in one go.

• Precision Factory Tolerance: Designed to meet or exceed original equipment standards for a secure fit, minimizing shaft vibration and maximizing tool operating life.

Crucial Fitment & Drive Shaft Notice

Please Read Before Purchasing: To ensure proper installation and prevent component damage, you must verify your equipment's drive shaft shape.

• Drive Shaft Requirement: This gearbox is engineered exclusively for Round Drive Shafts. It WILL NOT FIT square drive shafts. Please inspect your trimmer's flex or solid shaft tip before ordering.

Official Application Matrix

Product Specifications

• Part Type: Trimmer Working Gear Head / Gearbox Assembly

• Housing Material: Die-Cast Aluminum Alloy

• Shaft Spline Receiver: Round Configuration

• Condition: 100% Brand New

Interchange Reference Part Number:

• Factory OE Number: 4137 640 0100

Package Includes

• 1 × Premium Gearbox Head Assembly

• 1 × Matching Line Trimmer Head

Important Mechanical & Installation Notes

• Isolate Power Before Servicing: Ensure the engine is completely turned off and the spark plug wire is disconnected before removing the old gear head or installing the replacement.

• Check Factory Lubrication: While pre-greased during manufacturing, it is highly recommended to verify internal grease levels using a high-quality lithium-based gear grease prior to its initial high-RPM operation.

• Secure Clamp Bolts Evenly: When sliding the new gearbox onto the outer shaft housing, tighten the clamping bolts evenly in an alternating sequence to prevent cracking the aluminum collar or stripping the threads.