McLeod 1558 Flywheel Bolt Pack 8 Per Box GM LS 8-Bolt Crank LSA LSX 11mm

The McLeod 1558 is a Grade 8 steel flywheel bolt pack engineered exclusively for GM LS engines with an 8-bolt crankshaft flange - specifically the LSA and LSX blocks found in the 2009–2015 Cadillac CTS-V, 2012–2015 Chevrolet Camaro ZL1 (LSA), and 2017–2019 Chevrolet Camaro ZL1 (LT4). The 1558 ships 8 bolts per box on an M11 x 1.50 thread, torqued to 65 ft-lbs (88 Nm), and delivers improved flywheel register and increased clamping strength over OEM hardware. If your engine has a standard 6-bolt crank flange - LS1, LS2, LS3, LS6, LS7 - this is NOT your part; you need McLeod part 1556. The MLR1558 is the correct kit for the 8-bolt pattern only.

Why Flywheel Bolt Quality Matters

Flywheel bolts are among the most safety-critical fasteners in any drivetrain build. Reusing worn or torque-cycled hardware introduces real failure risk, and a flywheel separation at speed is catastrophic. The 1558 addresses this with purpose-engineered hardware built to McLeod Racing's exacting specifications, developed in partnership with ARP - a recognized leader in performance fasteners.

• Stretch bolts are single-use only. Factory GM flywheel bolts are torque-to-yield (TTY) fasteners. Once torqued, the shank permanently stretches. Reusing a TTY bolt gives you false torque readings, reduced clamp load, and a bolt that can back out under the cyclic loads of clutch engagement. Replace them every time the flywheel comes off.
• Torque-to-yield means one torque cycle. TTY fasteners are designed to reach their yield point on the first installation. Beyond that point the fastener's elastic range is exhausted. The McLeod MLR1558 bolts are specified for a clean 65 ft-lbs torque value - follow the spec exactly.
• Single-use warning. Do not re-torque, re-use after removal, or substitute hardware-store bolts. Grade 8 designation on the 1558 indicates tensile and proof-load standards specific to this application. Generic bolts of the same thread may not meet those standards.
• Torque specification: 65 ft-lbs (88 Nm). Always torque in a star/cross-hatch pattern in three progressive steps (approximately 20 ft-lbs, half torque, full 65 ft-lbs). Apply Loctite 242 (blue) threadlocker to threads. Never use an impact wrench - McLeod's installation documents explicitly state this can damage the bolts.

8-Bolt vs. 6-Bolt LS Crank - How to Identify Which One You Have

This is the most common ordering mistake on LS flywheel bolts. Both the 1558 (8-bolt) and the sibling MLR1556 (6-bolt) use identical M11 x 1.50 thread, so the thread itself gives you no indication of which kit you need. Count the bolt holes on your crankshaft flange before ordering.

• 6-bolt crank flange: LS1, LS2, LS3, LS6, LS7 - all standard Gen III/IV production LS engines used in Corvette C5/C6, GTO, G8, Camaro SS (2010–2015), Silverado SS, and most LS swap applications. These require McLeod part 1556 (6-bolt, 6-piece kit).
• 8-bolt crank flange: LSA supercharged 6.2L (Camaro ZL1 2012–2015 and CTS-V 2009–2015), LSX aftermarket performance blocks (LSX454, LSX376, LSX454R), and LT4 6.2L supercharged (Camaro ZL1 2017–2019). These require the 1558 (8-bolt, 8-piece kit).
• 9-bolt crank flange: LS9 6.2L dry-sump (Corvette ZR1 C6). This is a third pattern entirely - the LS9 uses 9 crank-to-flywheel bolt positions and neither the 1556 nor the MLR1558 applies.
• Visual check: Remove the transmission and inspect the crankshaft flange directly. Count the threaded holes evenly spaced around the flange. 6 holes = part 1556. 8 holes = 1558. 9 holes = LS9 application (different part).
• VIN decode shortcut: If your vehicle is a stock 2009–2015 Cadillac CTS-V or a 2012–2019 Chevrolet Camaro ZL1, you have an 8-bolt crank. Order the MLR1558.

McLeod Flywheel Bolt Pack Comparison

McLeod offers a full family of flywheel bolt kits covering virtually every domestic performance application. Use the table below to confirm the correct part for your engine:

What's Included - 1558

• 8 x Grade 8 steel flywheel-to-crankshaft bolts, M11 x 1.50 thread
• No washers included (not required for this application)
• No installation instructions included as a standalone hardware kit

Torque specification: 65 ft-lbs (88 Nm). Loctite 242 (blue) threadlocker is recommended but not included. Refer to McLeod Racing's published installation documentation for the full procedure.

Vehicle Fitment - McLeod 1558

The 1558 fits all production vehicles equipped with the LSA 6.2L supercharged V8 (8-bolt crank flange) and the LT4 6.2L supercharged V8 (8-bolt crank flange). Confirm your engine's crank flange bolt count before ordering. This kit does not fit standard LS1/LS2/LS3/LS6/LS7 engines with 6-bolt crank flanges.

Also fits any LSX aftermarket performance block (LSX454, LSX376, LSX454R) and any engine swap application using an LSA or LSX crankshaft with an 8-bolt crank flange.

Full Specifications

Warranty and Important Notices

McLeod Racing warrants the 1558 to the original purchaser against defects in material and workmanship for 90 days from the date of purchase. The warranty is non-transferable and does not cover products that have not been installed or used per McLeod's instructions, used products, or parts installed in a racing environment. Racing use voids the McLeod warranty entirely. Labor charges and consequential damages are not covered. Resolution is at McLeod's discretion repair, replacement, or credit. Returns require prior RMA authorization from McLeod Racing customer pays return shipping.

Under the federal Magnuson-Moss Warranty Act, an aftermarket fastener cannot void your vehicle's factory drivetrain warranty unless the dealer or manufacturer can demonstrate the aftermarket part directly caused the specific failure being claimed. Installing the 1558 per McLeod's torque specifications does not automatically void your factory warranty.

California Prop 65 Warning: This product can expose you to chemicals including lead and its compounds, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

About McLeod Racing

McLeod Racing LLC has been building high-performance clutch systems, flywheels, and drivetrain components for street and competition use for decades. Headquartered in Anaheim, California (1570 Lakeview Loop, Anaheim, CA 92807), McLeod develops every product in-house with direct input from professional racers and engine builders. Their flywheel bolt kits, including the 1558, are developed in partnership with ARP - the gold standard in performance fastener manufacturing.

Frequently Asked Questions

How do I know if I have an 8-bolt LS crank and need the 1558 instead of the 1556?
Count the threaded bolt holes on your crankshaft flange after removing the transmission. Eight evenly spaced holes mean you have an 8-bolt crank and need the 1558. Six holes mean you have the standard LS crank and need McLeod part 1556. If your vehicle is a factory 2009–2015 Cadillac CTS-V or a 2012–2019 Chevrolet Camaro ZL1, you have an 8-bolt crank. The LS9 (Corvette ZR1) uses a 9-bolt pattern and requires a different part entirely.

Can I reuse my factory flywheel bolts when reinstalling the flywheel?
No. Factory GM crank-to-flywheel bolts on LS engines are torque-to-yield (TTY) fasteners. They stretch permanently during the initial torque cycle, meaning the elastic range is consumed on first installation. Reusing a TTY bolt produces false torque readings and dangerously reduced clamp load. Any time the flywheel is removed, replace the bolts. The 1558 supplies a fresh set of 8 Grade 8 steel bolts for the 8-bolt crank flange.

What is the torque specification for the 1558?
McLeod Racing specifies 65 ft-lbs (88 Nm) for the M11 x 1.50 crank-to-flywheel bolts. Torque in a star/cross-hatch pattern in three progressive steps. Apply Loctite 242 (blue) threadlocker to the threads before installation. Do not use an impact wrench - McLeod's installation documentation explicitly states this can damage the bolts and is prohibited.

Does the 1558 fit the 2016 Camaro ZL1?
There was no 2016 Camaro ZL1 in production - the fifth-generation ZL1 launched for the 2017 model year with the LT4 engine. The 1558 fits the 2017, 2018, and 2019 Camaro ZL1 (LT4 6.2L, 8-bolt crank). It also fits the 2012–2015 Camaro ZL1 with the LSA 6.2L engine.

Does the 1558 fit the 2016 Cadillac CTS-V?
No. McLeod's fitment data for the 1558 covers the second-generation CTS-V (2009–2015) with the LSA 6.2L supercharged engine. The third-generation CTS-V (2016–2019) uses a different drivetrain configuration. Fitment for the 2016+ CTS-V has not been confirmed for this kit - contact McLeod Racing directly before ordering for that application.

Will the 1558 void my factory warranty?
Under the Magnuson-Moss Warranty Act, an aftermarket fastener cannot void your vehicle's factory drivetrain warranty simply because it was installed. The manufacturer or dealer must demonstrate a direct causal link between the aftermarket part and the specific failure being claimed. Installing the 1558 per McLeod's torque specifications and installation procedure does not automatically void your factory warranty.

Does the racing use exclusion in McLeod's warranty affect street builds?
McLeod's 90-day limited warranty covers defects in material and workmanship for street and performance street use. Racing environment use voids the warranty. If you are building a dedicated track or competition vehicle, be aware the warranty will not apply. For street-driven CTS-V and Camaro ZL1 applications, the standard 90-day warranty covers manufacturing defects.

What is the difference between the LSA and LT4 in the Camaro ZL1, and does it matter for the 1558?
The LSA is a Gen IV 6.2L supercharged engine used in the fifth-generation Camaro ZL1 (2012–2015) and CTS-V (2009–2015). The LT4 is a Gen V 6.2L supercharged engine used in the sixth-generation Camaro ZL1 (2017–2019) and 2016+ CTS-V. Despite being from different generations, both the LSA and LT4 share the same 8-bolt crankshaft flange bolt pattern, which is why the 1558 fits both. The thread size, bolt count, and torque specification are identical for both applications.

Does the 1558 work for LSX aftermarket engine builds?
Yes. LSX aftermarket performance blocks (LSX454, LSX376, LSX454R) use the same 8-bolt crankshaft flange pattern as the LSA. The 1558 is the correct flywheel bolt pack for any engine swap or performance build using an LSX block or an LSA crankshaft. This makes the MLR1558 a common choice for high-horsepower LS swap projects regardless of the vehicle being built.

What does the California Prop 65 warning on the 1558 mean?
California's Proposition 65 requires businesses to provide warnings before knowingly and intentionally exposing any person to chemicals listed by the state as known to cause cancer, birth defects, or other reproductive harm. The MLR1558 carries a Prop 65 warning because the steel hardware may contain trace amounts of listed chemicals such as lead compounds. This warning is a disclosure requirement, not an indication of unusual hazard relative to other steel fasteners. For full information, visit www.P65Warnings.ca.gov.