Drag Specialties Rear Master Cylinder Rebuild Kit – Harley FLT/FLH/FX/XL 1977‑1985 – Repl. OEM 42374‑77 Made in Japan

OVERVIEW

This Drag Specialties rear master cylinder rebuild kit restores safe braking performance on vintage Harley-Davidson motorcycles plagued by worn hydraulic components. Designed as a direct replacement for the Kelsey-Hayes style reservoir found on 1977–1985 models, the kit houses a durable metal piston and precision seals engineered for long-term reliability. It delivers factory-correct pedal feel and consistent stopping power across historic Touring, FX, and Sportster platform variants.

ENGINEERING & PERFORMANCE

The complete seven-piece assembly rebuilds degraded hydraulics by replacing failed plastic components with a reinforced metal piston that resists wear and corrosion. This configuration restores crisp brake pedal engagement and reliable fluid transfer under repeated stress. Every mating surface and seal meets or exceeds original equipment tolerances to eliminate sponginess and prevent future leakage during extended rides.

KEY FEATURES

• Replaces Harley-OEM part number 42374-77
• Compatible with three-quarter inch bore Kelsey-Hayes style master cylinders
• Complete seven-piece repair kit containing all necessary replacement hardware
• Features a solid metal piston instead of fragile plastic alternatives
• Engineered to meet or exceed original equipment specifications
• Restores firm brake pedal feel and consistent hydraulic pressure
• Direct bolt-on compatibility for historic Harley-Davidson braking systems
• Includes all required seals, gaskets, and mounting hardware for immediate installation

TECHNICAL SPECIFICATIONS

• Brand: Drag Specialties
• Part name: Rear Master Cylinder Rebuild Kit
• Part type: Brake hardware
• Material: Metal piston with synthetic seals and rubber components
• Supported years: 1977–1985
• Compatible Harley trims: Touring, FX, Sportster
• Made in Japan

FITMENT

• Harley Touring (1977–1985)
• Harley FX Series (1977–1985)
• Harley Sportster (1977–1985)

WHY HARLEY RIDERS CHOOSE THIS

Vintage Harley owners prioritize restoring factory braking geometry without compromising on modern reliability standards. This rebuild kit eliminates the common failure points of aging Kelsey-Hayes cylinders by supplying a heavy-duty metal piston that withstands heat cycling and vibration where factory plastic parts historically cracked. By returning precise hydraulic volume and resistance to the foot pedal, riders gain predictable deceleration on classic FL, FX, and XL frames without expensive full cylinder replacements or cross-platform swaps.