Chevrolet LS Flexplate Bolt Installation Guide (Gen III/IV Small Block) — XP983

This guide covers installation of the XOTIC PERFORMANCE™ XP983 flexplate bolt kit for the Chevrolet Gen III/IV LS small block. Prefer a printable copy? Download the PDF manual.

Why flexplate bolts deserve attention

Flexplate bolts hold a thin steel plate — carrying the ring gear and the torque converter — to the end of the crankshaft, through a load case that never lets up. Every combustion event tries to accelerate the crank; the converter's fluid coupling resists. The plate flexes by design, which means the joint is worked continuously rather than held statically, and an LS spinning to 6,500 rpm behind a stall converter works it hard.

Once clamp load drops, the plate begins to move against the crank flange, the holes elongate, and cracks propagate from there. On an LS swap in particular — where the flexplate, spacer and converter combination is often not the factory one — getting this joint right the first time matters. XOTIC PERFORMANCE™ fasteners are manufactured from our premium XOTIC 7200 steel alloy and backed by a lifetime warranty.

Before you start: verify first

Confirm that part number XP983 is compatible with your application before installing any components. Inspect the flexplate for cracks around the bolt holes and at the ring gear, and confirm the chamfer around each hole. Report any product damage to us before proceeding.

How to install flexplate bolts on a Chevrolet LS

1. Do not use washers — check the chamfer. These bolts install directly against the flexplate. Verify there is an adequate chamfer around each bolt hole to clear the bolt head radius.
2. Apply threadlocker. Apply Permatex Medium Strength Threadlocker BLUE to the bolt threads to prevent them loosening due to vibration.
3. Lubricate under the heads. Use the provided assembly lubricant under the head of each bolt. This reduces friction and allows for accurate torque readings.
4. Fit the flexplate and hand-tighten. Place the flexplate onto the crankshaft and run all bolts in by hand before any torque goes on.
5. Torque to 85 ft-lbs in an alternating cross pattern. Work across the plate rather than around it, so pressure is distributed evenly as the joint pulls up.

Chevrolet LS flexplate bolt torque spec

Frequently asked questions

What is the flexplate bolt torque spec for an LS?

85 ft-lbs, applied in an alternating cross pattern, with threadlocker on the threads and assembly lubricant under each bolt head. No washers.

Why both threadlocker and lubricant?

They do different jobs in different places. Threadlocker on the threads stops the bolt backing out under vibration. Lubricant under the head controls friction at the bearing face, which is where most of your applied torque is consumed — without it, the wrench reads 85 ft-lbs before the bolt has reached the intended clamp load.

Why no washers?

Because the flexplate is chamfered around each hole to accept the bolt head directly. Adding a washer changes the bearing surface and the effective grip length of the fastener.

Manual transmission — do I need this kit?

No. A manual car uses a flywheel; for 7/16" applications see the Chevrolet & Ford flywheel bolt guide (FW101).

Building the whole LS?

See our LS head stud guide (CP883) and the LS main stud guide (MS334).

Need help?

For technical support, email support@xotic-performance.com. All XOTIC PERFORMANCE™ fasteners are covered by our limited lifetime warranty. Finished your install? Tag #XOTICPERFORMANCE on Instagram for a chance to be featured.

© 2026 XOTIC PERFORMANCE™. This installation guide is an original copyrighted work of XOTIC PERFORMANCE™. Reproduction, distribution, or use of this content in whole or in part without written permission is prohibited. Doc ref: XP983 manual (web edition 2026.08).