Product Description
Shimano 10FMJ Handle Knob Seal (BNT5629)
The Shimano 10FMJ Handle Knob Seal (BNT5629) is a specialized rubber or synthetic gasket located at the base of the handle knob on Shimano baitcasting and spinning reels. This part is a critical component of Shimano’s "CoreProtect" or water-resistance systems, designed to prevent water, salt, and fine grit from entering the handle knob assembly where the precision ball bearings are housed.
Handle knob bearings are often the first to fail because they are highly exposed to the elements. The 10FMJ seal acts as the primary barrier, ensuring that the lubricant inside remains clean and the bearings remain smooth. If this seal is missing, torn, or brittle, you will likely notice your handle knobs becoming "crunchy" or seizing up shortly after exposure to saltwater or rain.
Product Specifications
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Part Name: Handle Knob Seal / O-Ring
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Part Number: 10FMJ
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Shimano Code: BNT5629
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Material: Plastic
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Function: Seals the gap between the handle knob and the handle shank to protect internal bearings.
Alternate Part Numbers
In various technical manuals and regional service catalogs, this part is identified by:
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BNT5629
Compatibility & Fitment
The 10FMJ (BNT5629) is found on many of Shimano’s modern high-performance reels that feature "removable" or "serviceable" handle knobs. It is a direct factory fit for:
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Shimano Curado Series: CU-200K, CU-201K, CU-300K, and MGL variants
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Shimano Tranx Series: TRX-200, TRX-300, TRX-400 (all high-speed and power-handle models)
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Shimano Stradic Series: Fits select modern spinning reel handles (Verify via BNT code)
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Shimano Grappler Series: Select jigging models using the BNT5629 specification.
Key Features
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Water Repellency: Manufactured from materials that naturally shed water and resist the "swelling" that occurs with some oils.
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Low Friction Design: Extremely thin and flexible to ensure that it provides a seal without creating "drag" or resistance when you turn the handle.
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Saltwater Resilience: Engineered to withstand UV exposure and salt crystallization without cracking.
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Direct OEM Fit: Guaranteed to sit flush in the recessed groove of the handle knob for a seamless appearance and maximum protection.
Maintenance & Installation Tips
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Don't Lose It: This seal is very small and often sticks to the handle knob when you pull it off the shaft. Be careful not to drop it during a field cleaning.
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Lubrication: When reassembling, apply a very light coat of silicone grease or Shimano DG06 to the seal. This helps it slide during rotation and improves its water-shedding capabilities.
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Inspect for Tearing: If the seal is pinched during installation, it will lose its effectiveness. Always ensure it is seated flat in the groove before sliding the knob onto the shaft.
Pro Tip: If your handle knob feels sluggish after installing a new seal, you may have pushed the knob too far onto the shaft, compressing the seal. Back off the Handle Knob Screw (BNT5630) slightly or ensure you haven't added too many shims. For a detailed layout of the handle assembly, refer to the PDF schematics at www.reelschematic.com.
