Heavy-Duty Brake Master Cylinder 1-3/4″ Bore – 4-Bolt Replacement for Commercial Vehicles and Industrial Equipment (M284249)

ABC Dynamics: Precision Parts for Uncompromising Performance.

Get reliable, high-volume stopping power for your **commercial vehicle, bus, or heavy equipment** with this brand new **M284249 Master Cylinder** from **ABC Dynamics**. Engineered with a powerful **1 3/4″ Bore** and a specific 4-bolt mounting pattern, this unit is the ideal, precise replacement for cylinders with casting number **FE777**. Trust ABC Dynamics for quality and safe, consistent braking whether on the road or the job site.

Key Specifications & Expert Features

• Bore Diameter: **1 3/4″** (High volume fluid displacement required for heavy braking systems.)
• Mounting: **4-Bolt** mounting pattern (Critical for fitment on specific heavy-duty vehicle chassis).
• Primary Line Threads: Features **3 x 1/2″-20** threads (Ensures secure connection for large brake circuits).
• Secondary Line Port: Includes a **1/8″-27 NPT** secondary port (For auxiliary systems or diagnostic testing).
• Repair Kit Compatibility: Compatible with repair kit **175MK**.

Verified Casting & Part Numbers (Cross-Reference)

This master cylinder is a confirmed, accurate replacement for the following casting numbers, commonly found on heavy-duty **trucks, buses, and industrial machinery**. Matching your existing number is the **most reliable method** to ensure correct fitment:

• FE777, 39, 616827, 618127
• 777, 777C, JML 262, 54837A

Expert Note: Fluid Displacement and Installation

Experience Tip: The large **1 3/4″** bore is critical for maximizing fluid displacement to large wheel cylinders or calipers. When installing this unit on a **heavy-duty vehicle**, ensure your bleed procedure is thorough to remove all air from the extensive lines, which is often the cause of a spongy pedal, even after a new master cylinder install.