Description
Product Overview
The CHENACC LS Harmonic Balancer Bolt is engineered for high‑performance LS engines, featuring a robust M16x2 thread size and a 4.05‑inch under‑head length. Crafted from premium alloy steel and hardened to Grade 10.9, the bolt delivers superior tensile strength and resistance to stretching or shearing under extreme torque. A durable painted exterior finish, complemented by an anti‑corrosion Dacromet coating, protects the fastener from moisture, heat, and chemical exposure typical in automotive environments. The hexagon head design enables quick, tool‑friendly installation, while the heavy‑duty manufacturer grade ensures the bolt meets or exceeds OEM specifications, including the original part number 12557840.
Usage
Designed specifically for General Motors Gen 3 and 4 LS engine families—including LS1, LS2, LS3, LS6, L59, L92, L96, L99, LC9, LH8, LMF, LMG, LY5, LM7, LR4, LQ4, and LQ9—this bolt is ideal for both professional mechanics and dedicated DIY enthusiasts. It is used to secure the harmonic balancer to the crankshaft, a critical component that dampens engine vibrations and maintains timing accuracy. Whether you are rebuilding an engine, performing a routine maintenance service, or replacing a worn bolt, the CHENACC balancer bolt provides a reliable, long‑lasting solution that restores original performance levels. 
Why Choose Us
CHENACC combines decades of automotive fastener expertise with rigorous quality control processes. Each bolt undergoes precise heat‑treatment and dimensional inspection to guarantee consistent hardness and thread integrity. Our commitment to using high‑grade materials means the bolt resists deformation even under high‑rpm conditions, reducing the risk of harmonic balancer slippage or engine damage. Backed by a 4.6‑star rating from 44 verified customers, the product demonstrates proven reliability and satisfaction. Additionally, the bolt is shipped with a clear UPC and ASIN for easy tracking and inventory management, ensuring you receive the exact component you need without guesswork.
Key Features
- Grade 10.9 alloy steel construction for maximum tensile strength
- Painted and Dacromet‑coated finish for superior corrosion resistance
- M16x2 thread with 4.05‑inch under‑head length for precise LS engine fitment
- Hexagon bolt head enables quick, tool‑free installation
- OEM‑compatible with part number 12557840, covering a wide range of LS models
FAQ
Is this bolt compatible with LS7 and LS9 engines?
No, the CHENACC LS Harmonic Balancer Bolt is not designed for LS7 or LS9 applications. It is intended for Gen 3 and 4 LS engines only.
What torque specification should be used when installing?
We recommend tightening the bolt to the manufacturer’s torque specification of 70 Nm (approximately 52 lb‑ft) to ensure proper clamping without over‑stress.
Can I reuse this bolt after removal?
While the bolt is engineered for durability, we advise using a new bolt for replacement to guarantee optimal strength and to maintain warranty compliance.
How does the Dacromet coating improve performance?
Dacromet provides a hard, corrosion‑resistant layer that protects the steel from rust and chemical exposure, extending the bolt’s service life even in harsh engine environments.
What tools are required for installation?
A standard 13 mm socket or wrench fits the hex head, and a torque wrench is recommended to achieve the correct tightening value.




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