Cloyes S921 Engine Timing Crankshaft Sprocket - Outer

Cloyes S921 Timing Crankshaft Sprocket

Cloyes S921 is a steel timing crankshaft sprocket built for specific engine applications that use a single-row timing chain. It features a helical tooth form for quieter operation and a precision-machined bore for a true fit during engine service or rebuild work.

Key Features

• Steel construction for engine timing durability
• Helical tooth form helps reduce timing system noise
• Precision-machined bore for accurate crankshaft fit
• Specific-fit design for confirmed applications
• Keyway notch included for proper alignment
• Single-row chain design
• 30-tooth sprocket with 2.73 in. outside diameter

Product Details

This Cloyes timing crankshaft sprocket is part of the Timing Crankshaft Sprocket line, which includes individual timing gears and sprockets as well as components used in complete timing kits. Cloyes designs and manufactures these parts with CAD-based engineering and advanced materials, then tests them for function and durability. The S921 is a direct-fit timing component for engines found in vehicles such as the Chevrolet Traverse, Buick Enclave, and Chevrolet Impala, making it a practical choice for timing service on GM and related applications.

This part cross-references GM OE numbers 12599721 and 12645465 for the same application.

Common Problems This Part Can Address

• Worn or damaged crankshaft sprocket teeth
• Timing chain noise caused by sprocket wear
• Improper chain tracking from an out-of-spec sprocket
• Timing system service during engine rebuilds
• Replacement of a failed original timing crankshaft sprocket

Installation Notes and Tips

Confirm engine application, position, and timing system configuration before installation. Cloyes recommends replacing the chain tensioner, sprocket, and guide components together when servicing the timing chain, since these parts work together to maintain chain tension and alignment. Verify bore size, tooth count, and keyway alignment against the vehicle’s timing system specifications before assembly.

Quality Assurance

Cloyes manufactures this sprocket using CAD-designed engineering and advanced materials, then subjects it to functional and durability testing to support reliable engine timing performance.