L5P BILLET FLEXPLATE ALLISON 17-UP

L5P Billet Flexplate

2017+ GM Duramax L5P

The L5P Billet Flexplate is designed to replace the factory flexplate on 2017 and newer GM Duramax L5P engines with a significantly stronger, one-piece billet steel design. The factory L5P flexplate relies on a stamped steel construction that can become a failure point when exposed to increased torque, aggressive tuning, towing, or high load conditions.

With the L5P platform producing substantial torque even in stock form, the flexplate becomes a critical link between the crankshaft and the torque converter. This billet flexplate eliminates the weaknesses of the OEM stamped unit, helping prevent cracking, warping, or center failure commonly seen under high torque transfer.

The flexplate bolts directly to the crankshaft, with the torque converter mounting to the flexplate. All engine torque is transferred through this component before reaching the converter and transmission input shaft. When torque output exceeds what the factory flexplate was designed to handle, failure can occur. Upgrading to a billet flexplate ensures reliable torque transfer and proper converter alignment, especially when paired with a high-performance or upgraded torque converter.

This flexplate is a recommended upgrade for tuned trucks, heavy towing applications, and performance builds where durability and safety are critical.

Key Features and Benefits

• One-piece billet steel construction
• Eliminates weak stamped factory flexplate design
• Built to handle high torque output from L5P engines
• Improves durability and torque transfer to the converter
• Ideal for towing, performance, and competition use
• Designed for use with upgraded torque converters

SFI Certification Notice

An SFI-certified flexplate is required for drag racing vehicles running 11.99 seconds or quicker in the 1/4 mile, 7.49 seconds or quicker in the 1/8 mile, or any vehicle exceeding 135 mph.

As of 2008, diesel automatic transmission flexplates must meet SFI Specification 29.3, which prohibits stamped metal construction. To remain compliant with SFI 29.3 requirements, the flexplate must be replaced every three years, regardless of condition.

Applications

• 2017+ GM Duramax L5P
• Automatic transmission-equipped vehicles