Harley Davidson Rear Drive Belt Pulley (40246-91 / 40225-86A)
Updated June 23, 2026
This rear drive belt pulley (also called a rear sprocket) is a toothed aluminum wheel that transfers power from the transmission to the rear wheel via the drive belt. It is a critical component of the final drive system on Harley-Davidson motorcycles, converting rotational force into forward motion. The pulley is splined to the rear wheel hub and meshes with the drive belt, which is driven by a smaller front pulley on the transmission output shaft.
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Function and Design
The rear belt pulley is a toothed sprocket that engages the drive belt, providing the final gear reduction in the motorcycle's drivetrain. It is typically made of lightweight aluminum to reduce unsprung weight. The pulley features 70 teeth and a 1.5-inch belt width, matching the standard belt size used on many Harley models. The pulley is bolted to the rear wheel hub and rotates with the wheel. Its teeth are precisely machined to ensure smooth belt engagement and minimize noise and vibration.
Vehicle Compatibility
This pulley is used on two distinct Harley-Davidson families. Part number 40246-91 fits Sportster models from 1991 to 2003, including XLH, XL, and XLC variants. Part number 40225-86A fits Touring models (Electra Glide, Road King, Ultra Classic), Dyna models, Softail models, and FXR models from 1986 to 2002. Both pulleys have 70 teeth and a 1.5-inch belt width, but they differ in bolt pattern and offset. Always verify the part number against your specific model and year before installation.
Common Failure Symptoms and Diagnosis
A worn or damaged rear pulley can cause belt slippage, a whining or clicking noise from the rear of the bike, and vibration during acceleration. Visually inspect the pulley for missing, chipped, or hooked teeth. Uneven wear patterns or a polished appearance on the tooth faces indicate belt misalignment or excessive tension. Also check for cracks in the pulley body or around the mounting holes. If the belt shows signs of fraying or uneven wear, the pulley should be inspected closely.
Installation Notes
Replacing the rear pulley requires removing the rear wheel and the drive belt. The pulley is secured by bolts (often with thread locker) and may be splined to the wheel hub. Clean the hub mating surface and apply anti-seize to the splines if needed. Torque the pulley bolts to the manufacturer's specification (typically 35-45 ft-lbs, but verify with a service manual). After installation, check belt tension and alignment, and adjust as necessary. A new belt is recommended when replacing the pulley to ensure proper wear-in.
