New Brake Master Cylinder 1-1/4-inch bore size FE21721 5454330 21721C
Bexar Pro Components: Heavy-Duty Reliability for Fleet & Industry.
Key Specifications & Expert Features
- Bore Diameter: 1-1/4-inch bore size (High-volume fluid displacement)
- Outlet Size: 7/16-26 INV (Standard inverted flare connection)
- Application: Heavy-duty commercial trucks and industrial machinery.
- Companion Repair Kit: 33MK (View Compatible Kit)
Verified Casting & Part Numbers
Matching your existing part number is the most reliable method to ensure correct fitment. This unit replaces:
- FE21721
- 5454330
- 21721C
- 618108
- 3773856
- FD21721
Expert Installation & Field Note
Based on our shop experience specializing in heavy-duty brakes since 1985: The 1-1/4-inch bore size is designed for high-pressure requirements in commercial and industrial settings. Pushrod alignment is absolutely critical to prevent seal scoring. When installing on heavy equipment, ensure the pushrod is perfectly centered within the piston pocket. Always perform a complete system bleed using fresh DOT fluid following installation.
⚠ CRITICAL: Verify Specifications
To ensure safety, verify that this master cylinder’s 1-1/4-inch bore size and 7/16-26 INV outlet match your existing unit exactly before purchasing.






