Dorman - First Stop Brake Master Cylinder P/N:M630405

Restore firm, dependable brake pedal feel with the Dorman – First Stop Brake Master Cylinder M630405. This master cylinder converts the force applied at the brake pedal into the hydraulic pressure that operates the brake circuits, and it installs as a direct-fit replacement for the 2008 Cadillac CTS [All] and 2008 Cadillac STS [All].

• 100% new build: made entirely from new materials — not remanufactured — for consistent quality and safety.
• Aluminum housing: the cylinder housing is built to match the casting material of the original part for similar performance.
• EPDM rubber components: all rubber parts use a high-quality EPDM compound for resistance to glycol-based brake fluid.
• Built to spec: made to meet rigorous SAE International standards, with a 1.031 in bore, two outlets, and M13 x 1.5 outlet threads at a 1.5 mm pitch.

The reservoir and sensor are included; mounting hardware is not included, so consult the vehicle service information for the correct fasteners and whether they may be reused. Signs this part may need replacing include a pedal that slowly sinks under steady pressure or internal fluid loss — diagnose the cause first, and if a failed master cylinder is confirmed, this replaces it. Country of origin: China.

Interchange: 100-4048 · 1004048 · 10-3354 · 103354 · 130.62153 · 15267509 · R135113 · Manufacturer part number M630405.