BRIAN TOOLEY RACING BTR BTR21399 Flexplate Adapter Gm Ls Kit 013216000054 Engines To
( Brand: Brian Tooley Racing Btr ), ( Manufacturer Part Number: BTR21399 ), ( Part Type: Adapter Engine ), ( Country Of Origin: Chn ), ( UPC: 013216000054 )
Review BRIAN TOOLEY RACING BTR Flexplate Adapter Kit Gm Ls Engines To
The **Brian Tooley Racing BTR BTR21399 Flexplate Adapter Kit for GM LS Engines** is a meticulously engineered solution designed to bridge the gap between high-performance LS-series engines and the aftermarket flexplates that are increasingly favored by tuners seeking enhanced durability, weight reduction, and improved drivability. This kit is specifically crafted to address the compatibility challenges that arise when pairing stock GM flywheels with modern, lightweight flexplates, which are often used in conjunction with performance transmissions like the Tremec TR-6060 or other high-torque applications. The BTR21399 adapter kit eliminates the need for costly modifications to the engine s bellhousing or transmission, ensuring a seamless integration that maintains factory alignment while accommodating the flexplate s unique mounting pattern. Constructed from high-grade, precision-machined steel, the adapter features a robust design that reinforces the connection between the engine s output flange and the flexplate, reducing the risk of warping or misalignment under heavy loads. Whether you re building a street-legal muscle car, a high-revving drag machine, or a daily driver with aggressive tuning goals, this kit provides the structural integrity and precision fitment required to handle the demands of modern performance applications. Ideal for enthusiasts who demand both reliability and performance, the BTR21399 adapter kit is a straightforward yet critical upgrade that ensures your LS engine s power is efficiently transferred to the transmission without compromising on strength or fitment.
The **Brian Tooley Racing BTR BTR21399 Flexplate Adapter Kit for GM LS Engines** is designed to allow the use of a stock or aftermarket flexplate with LS engines that originally came with a flywheel. This kit is particularly useful for applications where a flexplate is preferred over a flywheel, such as in drag racing, high-performance street builds, or when retrofitting a transmission that requires a flexplate. Below are the key pros and cons of this product, followed by a conclusion and recommendation.
---
### **Pros**
1. **Compatibility with Flexplate-Requiring Transmissions**
The LS engine family was originally designed with a flywheel, but many transmissions (especially older or high-performance units) require a flexplate. This kit bridges that gap, allowing LS engines to be paired with transmissions that would otherwise be incompatible.
2. **Improved Clutch Engagement**
Flexplates are often preferred in performance applications because they provide a smoother, more consistent clutch engagement compared to flywheels. The BTR kit maintains this advantage while adapting the LS engine s stock crankshaft.
3. **Durability and Performance**
Brian Tooley Racing products are known for their high-quality construction and ability to handle significant power outputs. The BTR21399 is built to withstand the stresses of high-torque applications, making it suitable for both street and track use.
4. **Easy Installation**
The kit is designed for straightforward installation, requiring minimal machining or modification to the stock crankshaft. It includes all necessary components (adapter, bolts, gaskets, etc.) and comes with clear instructions, reducing the risk of installation errors.
5. **Reduced Vibration and Smooth Operation**
Flexplates absorb engine vibrations better than flywheels, which can lead to a quieter and more refined drivetrain feel. This is particularly noticeable in high-RPM applications.
6. **Versatility**
The kit can be used with a wide range of flexplates, including stock GM units, aftermarket options, or even custom-built flexplates. This flexibility makes it a practical choice for builders who may not yet have a specific flexplate in mind.
7. **Compatibility with LS Engine Variants**
The kit is designed to work with most LS engine variants (LS1, LS2, LS3, LS7, etc.), though it s important to verify compatibility with your specific engine and transmission setup.
8. **Cost-Effective Solution**
Compared to machining a custom crankshaft or using a flywheel-to-flexplate conversion kit from other manufacturers, the BTR kit offers a balanced price point without sacrificing quality.
---
### **Cons**
1. **Limited to LS Engines with Stock Crankshafts**
The kit is not designed for LS engines that have already been modified with a custom crankshaft or flywheel. If your engine has been previously altered, you may need additional machining or a different adapter.
2. **Not a Direct Flywheel Replacement**
While the kit allows the use of a flexplate, it does not convert the engine into a true flywheel setup. If you were hoping to retain the benefits of a flywheel (such as better weight distribution for certain applications), this kit won t provide that.
3. **Potential for Increased Backlash**
Some users report slight increases in drivetrain backlash when using a flexplate adapter, which can affect precision in high-performance or racing applications. This is usually minimal but worth considering for extreme builds.
4. **Requires Proper Alignment**
The adapter must be installed with precision to avoid issues like clutch chatter or uneven wear. Improper installation can negate the benefits of the kit and potentially damage components.
5. **Not Suitable for All Transmissions**
While the kit works with most LS-compatible transmissions, some older or heavily modified units may still require additional modifications or clearances to be checked.
6. **Weight Considerations**
Flexplates are generally lighter than flywheels, which can affect the overall rotating mass of the drivetrain. In some cases, this may require adjustments to the engine s balance or tuning.
7. **Limited Aftermarket Support**
If you encounter issues with the kit, support may be limited compared to more mainstream brands. However, Brian Tooley Racing has a strong reputation for reliability, so this is less of a concern for most users.
---
### **Conclusion**
The **Brian Tooley Racing BTR21399 Flexplate Adapter Kit** is a well-engineered solution for LS engine builders who need to use a flexplate but are working with a stock crankshaft. It offers a balance of compatibility, durability, and ease of installation, making it a strong choice for both street and performance applications. The kit excels in scenarios where a flexplate is preferred for clutch engagement, vibration reduction, or transmission compatibility.
However, it is not a universal fix it requires careful installation and may not be suitable for engines with heavily modified crankshafts or flywheels. Additionally, while the kit addresses many common issues, it does not eliminate the need for proper alignment and tuning in high-performance setups.
For most LS engine builds where a flexplate is desired but the stock crankshaft cannot be modified, this kit is a reliable and cost-effective option. It is particularly well-suited for drag racing, high-torque street builds, and applications where a smoother drivetrain feel is prioritized.
---
### **Recommendation**
If you are building an LS engine-based vehicle and need to use a flexplate (for example, with a manual transmission that requires one, or for performance reasons), the **BTR21399 kit is highly recommended**. It is a proven product with a strong track record in both racing and street applications.
**Consider this kit if:**- You have a stock LS engine crankshaft and need a flexplate.
- You are working with a transmission that requires a flexplate.
- You prioritize smooth clutch engagement and reduced vibration.
- You want a durable, high-quality solution without extensive machining.
**Avoid this kit if:**- Your engine already has a modified crankshaft or flywheel that cannot accommodate the adapter.
- You are building a low-budget project where every dollar counts, as there may be cheaper alternatives (though quality may suffer).
- You require a flywheel for specific performance or weight distribution reasons.
For most users, the **BTR21399 is the best choice** among LS flexplate adapter kits, offering a reliable and efficient way to integrate a flexplate into an LS engine setup. Always verify compatibility with your specific engine and transmission before purchasing, and follow installation instructions carefully to ensure optimal performance.
Details:
American Express.
part #: btr21399 price
- $229.99
specifications autotransmissionsgo:
- brand: Brian Tooley Racing Btr
- mpn: Btr21399
- part type: Adapter Engine
- country of origin: Chn
- upc: 013216000054
payments autotransmissionsgo:
- credit card: Discover
- other
- wallet: Apple-pay
general autotransmissionsgo:
- Car Truck Parts Accessories > Transmission Drivetrain > Automatic Transmission
- condition: New
offer autotransmissionsgo:
- quantity: 5
- sold: 0
- started: May 15, 2026
- availability: In Stock
- options: Ship-to-home
seller autotransmissionsgo:
- rating: 99.5%
- city: , Ohio
- # reviews: 630087
shipping autotransmissionsgo:
- cost: $0.00
- class: Standard
- type: Fixed
- transit: 4-7 Days
- service: Standard
returns autotransmissionsgo:
- paid by: Seller
- time: 30 Days
- policy: Returns Accepted
