Product Description
Shimano 10BJ1 Idle Gear (C)
The Shimano 10BJ1 Idle Gear (C) is a fundamental internal component of the level wind drive system in Shimano round baitcasting reels. This gear serves as a critical link in the gear train, transferring rotational energy to ensure the line guide oscillates back and forth with surgical precision.
Precision-molded from a high-density, wear-resistant polymer, the 10BJ1 is designed to provide quiet operation and reduce mechanical friction within the side plate. If your reel's line guide has stopped moving or is hesitating during the retrieve, it is often due to stripped or worn teeth on the idle gear. Replacing this part restores the even line lay necessary for long, bird-nest-free casts and consistent drag performance.
Product Specifications
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Part Name: Idle Gear (C)
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Part Number: 10BJ1
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Shimano Code: BNT1938
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Material: Advanced Engineering Composite
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System: Level Wind / Drivetrain oscillation
Alternate Part Numbers
This part is frequently cross-referenced or identified in technical manuals by the following alternate number:
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BNT1938
Compatibility & Fitment
The 10BJ1 (BNT1938) idle gear is a factory-standard component for Shimano’s Corsair and related round reel series. It is a direct fit for the following models:
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Shimano Corsair Series: CS-300, CS-300A, CS-301A
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Shimano Catala Series: Fits select 300-size models (Verify via schematic)
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Shimano Cardiff Series: Select legacy versions (Check for BNT1938 requirement)
Pro Tip: During installation, ensure the idle gear shaft is clean and lightly lubricated with a plastic-safe synthetic grease. Over-tightening the side plate screws can sometimes pinch the idle gear assembly, so always check for free movement before final assembly. For a complete visual guide to the internal gear stack, you can download the PDF schematic for your specific model at www.reelschematic.com.
Key Features
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Perfect Synchronization: Ensures the line guide tracks perfectly with the spool's rotation speed.
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Durability: High-grade polymer construction resists stripping even under the stress of heavy lures.
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OEM Fit: Guaranteed to match the tooth pitch and diameter of your original factory gear.
