Product Description
Shimano 10FNL Handle Nut (BNT1788)
The Shimano 10FNL Handle Nut (BNT1788) is a specialized fastener used to secure the handle assembly to the drive shaft of Shimano baitcasting reels. While it looks similar to other handle nuts, the 10FNL is specifically designated for Left-Hand (LH) retrieve models.
Unlike standard nuts that tighten clockwise, this is a Reverse-Thread (Left-Hand Thread) nut. This design is critical for left-hand retrieve reels because the rotational force applied while cranking the handle would eventually loosen a standard right-hand nut. If you try to force this nut onto a right-hand retrieve reel, you will strip the threads of the drive shaft.
Product Specifications
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Part Name: Handle Nut (Left-Hand)
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Part Number: 10FNL
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Shimano Code: BNT1788
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Material: Anodized Aluminum / Plated Steel
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Threading: Left-Hand Thread (Reverse Thread)
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Function: Anchors the handle to the drive shaft on LH retrieve reels.
Alternate Part Numbers
This part is commonly cross-referenced in Shimano service manuals and parts stores as:
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BNT1788
Compatibility & Fitment
The 10FNL (BNT1788) is the standard nut for many of Shimano’s legendary left-hand low-profile and round baitcasting reels. It is a direct factory fit for the following series:
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Shimano Calcutta Series: CT-401, CT-401B, CT-701, CT-701B (Large round reels)
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Shimano Curado Series: CU-201B, CU-201BSV, CU-201DPV (The classic "Green" LH Curados)
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Shimano Citica Series: CI-201B, CI-201D
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Shimano Bantam Series: Fits various LH-spec Bantam models using the BNT1788 hardware.
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Shimano Cardiff Series: CDF-201A, CDF-301A, CDF-401A
Key Features
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Directional Safety: Features a reverse-thread pitch to ensure the nut stays tight during high-torque cranking.
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Precision Machining: Typically a 10mm or 11mm hex head (verify specific model) designed to seat perfectly within a Handle Nut Retainer.
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Corrosion Shield: High-quality plating prevents the nut from "seizing" to the drive shaft due to saltwater exposure.
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OEM Tolerance: Guaranteed to match the thread pitch of Shimano’s stainless steel drive shafts without wobbling.
Critical Installation Tips
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Remember: "Lefty-Tighty": To tighten this nut, you must turn it Counter-Clockwise. To loosen it, turn it Clockwise.
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Hand-Start Only: Because it is a reverse thread, it is very easy to confuse directions and cross-thread the part. Always spin it on by hand for at least 3 full rotations before using a wrench.
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The Retainer Plate: Never use this nut without its matching Handle Nut Retainer (Plate) and screw. The plate is the only thing preventing the nut from backing off during use.
Pro Tip: If you are unsure if your reel is Left or Right-hand retrieve, look at the model number. Shimano reels ending in "1" (e.g., 201, 301, 401) are almost always Left-Hand retrieve and require this 10FNL nut. You can find the full assembly diagram at www.reelschematic.com.
