BTR BTR57940 LS Flywheel Bolt Extended Length Flexplate Fastener Gen III Gen IV

The Brian Tooley Racing (BTR) BTR57940 is an extended-length flywheel and flexplate bolt engineered specifically for GM Gen III and Gen IV LS engines. Designed as a direct replacement for GM OEM part number 19257940, this bolt features an extended length required for proper use when a flexplate spacer is present — it is not intended for use without a spacer. Sold individually, allowing you to order the exact quantity needed for your build.

These fasteners are machined from alloy steel with a protective zinc coating for corrosion resistance, providing reliable clamping force to secure the flywheel or flexplate to the LS crankshaft. They are a key component in BTR's LS flexplate adapter kit (BTR21399), which is used for adapting TH350, TH400, 700R4, and Powerglide transmissions to LS engines.

Key Features:

• Extended length design — required for use with a flexplate spacer
• Machined alloy steel construction with zinc coating for corrosion protection
• Compatible with GM Gen III and Gen IV LS engines
• Replaces GM OEM part number 19257940
• Sold individually — order the quantity needed for your application
• Used in BTR Flexplate Adapter Kit (BTR21399) for TH350/TH400/700R4/Powerglide swaps

Whether you are replacing a worn fastener or building a custom LS swap, the BTR57940 provides the correct extended-length hardware to ensure proper flywheel or flexplate attachment with a spacer installed.