Product Description

SHIMANO 10988 CLICK SPRING (BNT4931, BNT4939 & TGT2021)

The Power Behind the Alarm

The Shimano 10988 Click Spring (Part Nos. BNT4931, BNT4939, or TGT2021) is the stainless steel tension spring responsible for the operation of the spool clicker (line alarm) on Shimano's modern heavy-duty baitcasting and jigging reels.

This spring applies constant pressure to the click pawl, forcing it into the teeth of the click gear. When the clicker switch is engaged, this spring ensures the pawl snaps audibly over every tooth. If your reel's clicker sounds weak, "mushy," or fails to stay engaged during a run, this spring has likely lost its tension or broken due to fatigue.

Product Specifications

• Part Name: Click Spring (Spool Alarm Spring)

• Manufacturer: Shimano

• Part Number (MPN): BNT4931 / BNT4939 / TGT2021 (Interchangeable across specific models)

• Schematic Code: 10988 (Location key on select diagrams)

• Material: Stainless Spring Steel

• Installation Position: Left Side Plate (Non-Handle Side), typically under the Clicker Button assembly.

Compatible Models

This part is shared across Shimano's "Big Baitcasting" and heavy saltwater jigging platforms.

• Shimano Tranx Series:

  • TRX 500 HG, TRX 500 PG (Tranx 500)

  • TRX 300 / 400 (Check specific generation; mostly 500 size uses this specific heavy-duty spring)

• Shimano Ocea Jigger Series:

  • Ocea Jigger 1000, 1500, 2000, 3000 (Newer HG/PG models)

  • Ocea Jigger F Custom

• Shimano Calcutta Conquest:

  • Select newer saltwater Conquest models (300/400 sizes)

• Shimano Torium A / Trinidad A:

  • Check schematics; some newer star drag models use this spring style for the clicker mechanism.

Installation & Reference

To ensure this is the correct spring for your reel, please cross-reference the part numbers BNT4931, BNT4939, or TGT2021 with your reel's service diagram.

• Schematic Diagrams: For detailed PDF schematics and part location verification, please visit www.reelschematic.com.

• Alternate Part Number: BNT4931, TGT2021

Installation Tip:

1. Tension: This is a strong spring. When installing it into the side plate, be careful—it is under compression and can easily fly out if not held down securely while you replace the retainer or cover plate.

2. Grease: Apply a coating of Shimano Permalub or marine grease to the spring and the pivot point of the pawl. This prevents corrosion (common in this area on saltwater reels) and reduces friction wear between the spring and the pawl.

3. Position: Ensure the "arm" of the spring is resting correctly against the back of the Click Pawl. If it's on the wrong side, the clicker will not engage.