S&S Cycle Rocker Arm Guardian Kit for 2017-Up Harley-Davidson M8

S&S Cycle Rocker Arm Guardian Kit for 2017-Up Harley-Davidson M8

The Milwaukee-Eight’s stock top-end hardware is a known weak point in high-performance builds – rockers that prioritize the rocker boxes over the valve springs, and head bolts that aren’t engineered for repeated big-bore service. This Guardian Kit addresses every one of those failure points in one comprehensive package, replacing the rocker shafts, rocker arms, head bolts, and rocker studs with hardware rated for the punishment a built M8 delivers.

Key Features

• Complete top-end hardware kit: forged roller rocker arms, rocker arm shafts, rocker arm stud kit, and head bolt kit
• Forged 8620 steel roller rocker arms with FEA-optimized geometry spray oil directly onto valve springs – not the rocker boxes
• Hardened and surface-ground rocker arm shafts for ultimate precision and durability
• 200,000 psi head bolts deliver 14 percent greater strength than stock
• Black oxide rocker arm stud kit with 12-point nuts

Technical Specifications

• Rocker Arms: Forged 8620 steel, FEA-designed, roller tip
• Rocker Arm Shafts: Hardened and surface ground, direct stock replacement
• Head Bolts: 8640 heat-treated steel, 200,000 psi ultimate tensile strength, 14% over stock, black oxide, 9/16 inch 12-point with integral washer
• Rocker Stud Kit: Black oxide finish with 12-point nuts
• Fitment: 2017-Up Harley-Davidson M8 models

Fitment Notes

• Fits 2017 and newer Harley-Davidson models equipped with the Milwaukee-Eight engine
• Rocker covers not included – verify rocker cover compatibility before ordering
• Recommended for all big bore and high-compression M8 builds to protect the top end under increased cylinder pressures
• Review the Fitment tab for the complete year and model breakdown