PolarStar Gearbox Shim Set for HPA Cylinder Conversion Kits (0.157″)
When it comes to maximizing the performance of your HPA setup, even the smallest components make a big difference. The PolarStar Gearbox Shim Set 0.157 HPA is a precision upgrade designed to eliminate engine movement inside your gearbox, ensuring consistent air seal, reliable BB feeding, and peak performance from your HPA system.
Built specifically for PolarStar cylinder conversion kits, this shim set is an essential addition for anyone running F2, F1, JACK, or Kythera systems.
Eliminate Engine Movement for Consistent Performance
One of the most overlooked issues in HPA builds is slight engine movement inside the gearbox shell. Due to variations in gearbox pin sizes across manufacturers, even high-end builds can suffer from unwanted shifting.
The PolarStar shim set solves this problem by:
- Securing the HPA engine firmly in place
- Preventing forward and backward movement
- Stabilizing the cylinder within the gearbox shell
- Maintaining consistent alignment during operation
This results in improved reliability and repeatable shot performance, especially in high-demand builds.
Improve Air Seal & BB Feeding
When your HPA engine shifts, it directly affects how far the nozzle extends into the hop-up chamber. Even minor inconsistencies can lead to:
- Poor BB seating
- Inconsistent air seal
- FPS fluctuations
- Reduced accuracy
By locking the engine into position, these shims help maintain optimal nozzle alignment, ensuring:
- Consistent air compression
- Reliable BB feeding
- Improved shot-to-shot consistency
This is a simple upgrade with a major impact on performance.
Precision Fit for Common Gearboxes
The 0.157″ shim size is designed to match common gearbox pin tolerances, making installation straightforward and effective.
Fitment benefits:
- Compatible with most standard gearbox shells
- Designed for easy drop-in installation
- Multiple sizes available for fine-tuning your setup
- Ensures a snug and secure fit regardless of manufacturer variation
This flexibility allows you to dial in your build with precision, no matter your platform.
Durable Brass Construction
Constructed from high-quality brass, these shims are built to withstand repeated use and maintain their integrity over time.
Material advantages:
- Strong and wear-resistant
- Maintains shape under pressure
- Corrosion-resistant for long-term durability
- Reliable performance in all conditions
This ensures your gearbox remains stable and consistent even under heavy use.
Compatible with All PolarStar Cylinder Kits
The shim set is fully compatible with all major PolarStar cylinder conversion systems, including:
- PolarStar F2
- PolarStar F1
- PolarStar JACK
- PolarStar Kythera
This makes it a universal solution for PolarStar users looking to optimize their setup.
Why Shimming Matters in HPA Builds
Unlike traditional AEGs, HPA engines rely heavily on precise alignment and consistency. Even minor internal movement can compromise performance.
By installing the correct shim size:
- You eliminate mechanical inconsistencies
- Improve overall efficiency
- Extend the lifespan of your components
- Achieve more predictable and accurate shots
It’s a small upgrade that delivers professional-level results.
Quick & Easy Installation
The PolarStar shim set is designed for simple installation, making it accessible for both beginners and experienced techs.
Installation highlights:
- No complex modifications required
- Fits directly into gearbox pin areas
- Fast setup with immediate performance gains
- Ideal for tech builds and maintenance upgrades
Whether you’re building a new HPA setup or refining an existing one, this is a must-have tuning component.
Key Features
- Precision 0.157″ shim size for common gearbox pins
- Durable brass construction
- Prevents HPA engine movement inside gearbox
- Improves air seal and BB feeding consistency
- Enhances overall performance and reliability
- Compatible with PolarStar F2, F1, JACK, and Kythera systems
- Easy drop-in installation
- Designed for most standard gearbox shells
Fine-Tune Your HPA Performance
The PolarStar Gearbox Shim Set (0.157″) is a small but critical upgrade that ensures your HPA engine performs at its best. By eliminating internal movement and stabilizing your setup, it delivers consistent power, accuracy, and reliability every time you pull the trigger.
For players serious about performance, this is an essential component in any high-quality HPA build.
Available now at CQCAirsoft.com – dial in your setup and shoot with confidence.




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