Dorman M101266 Brake Master Cylinder

Name: Dorman M101266 Brake Master Cylinder
Brand: Dorman
SKU: BKKX-M101266
Price: 64.36 USD
Availability: InStock

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OE Direct Replacement — Bolt-on fit, no modifications needed

Fitment: Chevrolet and GMC, P20, P2500, G30, G3500, P30, P3500, C20, C20 Suburban, C30, K20, K20 Suburban, C2500, C2500 Suburban, K2500, K2500 Suburban, C25, C25 Suburban, C35, G35, K25, K25 Suburban, P25, P35, C10 Suburban, K10 Suburban, C15 Suburban, K15 Suburban, C20 Pickup, C30 Pickup, G30 Van, P30 Van, C35/C3500 Pickup, G35/G3500 Van, and P35/P3500 Van

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Overview of Dorman Brake Master Cylinder M101266

The Dorman Brake Master Cylinder M101266 is designed for reliable brake hydraulics performance in select Chevrolet and GMC trucks and SUVs. This master cylinder includes a reservoir and is engineered to meet the specific needs of vehicles like the Chevrolet C10 Suburban and GMC K2500 Suburban.

Master cylinder bore diameter: 1.25 inches
Constructed from durable cast iron material
Includes reservoir for fluid storage
Two outlet ports for brake line connections
Rearward outlet size: 1/2-20 thread
Secondary outlet thread diameter: 9/16-18
Package contains the master cylinder only; mounting hardware not included

Detailed Product Description

The Dorman M101266 brake master cylinder is built with a 1.25-inch bore diameter and cast iron construction to provide consistent hydraulic pressure for braking systems. It features two outlets with specific thread sizes—1/2-20 for the rearward outlet and 9/16-18 for the secondary outlet—ensuring compatibility with the brake lines on Chevrolet and GMC trucks such as the C20, C2500, and P3500 models. The included reservoir allows for proper brake fluid containment and circulation, essential for maintaining brake system integrity. This master cylinder is designed to replace original equipment components and restore proper brake function.

Compatible Vehicles and Applications

This brake master cylinder is compatible with a range of Chevrolet and GMC trucks and SUVs, including:

Chevrolet C10 Suburban, C20, C20 Suburban, C30
Chevrolet C2500, C2500 Suburban
GMC G30, K10 Suburban, K20, K20 Suburban
GMC K2500, K2500 Suburban, P20, P30, P2500, P3500

Common Issues Addressed by This Master Cylinder

Brake pedal sinking or sponginess due to internal leaks
Brake fluid leaks around the master cylinder
Reduced braking performance or uneven brake pressure
Contaminated or damaged brake fluid reservoir
Failure of the original master cylinder causing brake system warning lights

Installation Notes and Tips

Ensure the brake system is properly bled after installation to remove air
Verify thread sizes (1/2-20 and 9/16-18) match brake line fittings
Mounting hardware is not included; reuse original hardware or source separately
Inspect brake lines and hoses for wear during installation
Follow vehicle-specific service manual instructions for removal and installation

Quality Assurance and Warranty

Dorman manufactures this brake master cylinder to meet or exceed OEM specifications for durability and performance. The cast iron construction provides long-lasting strength under demanding conditions. While mounting hardware is not included, the product undergoes quality checks to ensure proper fit and function. Warranty coverage details should be confirmed with the point of purchase or manufacturer documentation.

Brand	Dorman
Part Number	M101266
Master Cylinder Bore Diameter	1.25
Master Cylinder Material	Cast Iron
Mounting Hardware Included	No
Number of Outlets	2
Package Contents	Master Cylinder
Rearward Outlet Size	1/2-20
Reservoir Included	Yes
Secondary Outlet Thread Diameter	9/16-18
Sensor Included	No

This part fits 90 vehicles. Search below:

Year	Make	Model	Fuel Type	Position	Notes
1984	Chevrolet	P20	GAS	N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1984	GMC	P2500	GAS	N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1983	Chevrolet	G30		N/A	For vehicles with Single Rear Wheel (SRW), the brake master cylinder bore size is 1.25 inches.
1983	Chevrolet	P20	GAS	N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1983	GMC	G3500		N/A	For vehicles with Single Rear Wheel (SRW), the brake master cylinder bore size is 1.25 inches.
1983	GMC	P2500	GAS	N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1982	Chevrolet	G30		N/A	For vehicles with Single Rear Wheel (SRW), the brake master cylinder bore size is 1.25 inches.
1982	Chevrolet	P20	GAS	N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1982	GMC	G3500		N/A	For vehicles with Single Rear Wheel (SRW), the brake master cylinder bore size is 1.25 inches.
1982	GMC	P2500	GAS	N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1981	Chevrolet	G30		N/A	For vehicles with Single Rear Wheel (SRW), the brake master cylinder bore size is 1.25 inches.
1981	Chevrolet	P20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1981	Chevrolet	P30		N/A	For vehicles with a GVW of 7,600 to 8,200 lbs, with a bore size of 1.25 inches, excluding Motorhome Chassis.
1981	GMC	G3500		N/A	For vehicles with Single Rear Wheel (SRW), the brake master cylinder bore size is 1.25 inches.
1981	GMC	P2500		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1981	GMC	P3500		N/A	For vehicles with a GVW of 7,600 to 8,200 lbs, with a bore size of 1.25 inches, excluding Motorhome Chassis.
1980	Chevrolet	C20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1980	Chevrolet	C20 Suburban		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1980	Chevrolet	C30		N/A	Fitment: 6,600-8,200 Lb. GVW, 1.25 In. Bore
1980	Chevrolet	G30		N/A	7,700 to 8,400 Lb. GVW, Bore: 1.25 In.
1980	Chevrolet	K20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1980	Chevrolet	K20 Suburban		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1980	Chevrolet	P20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1980	Chevrolet	P30		N/A	For vehicles with a GVW of 7,600 to 8,200 lbs, with a bore size of 1.25 inches, excluding Motorhome Chassis.
1980	GMC	C2500		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1980	GMC	C2500 Suburban		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1980	GMC	G3500		N/A	7,700 to 8,400 Lb. GVW, Bore: 1.25 In.
1980	GMC	K2500		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1980	GMC	K2500 Suburban		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1980	GMC	P2500		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1980	GMC	P3500		N/A	For vehicles with a GVW of 7,600 to 8,200 lbs, with a bore size of 1.25 inches, excluding Motorhome Chassis.
1979	Chevrolet	C20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1979	Chevrolet	C20 Suburban		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1979	Chevrolet	C30		N/A	Fitment: 6,600-8,200 Lb. GVW, 1.25 In. Bore
1979	Chevrolet	G30		N/A	7,700 to 8,400 Lb. GVW, Bore: 1.25 In.
1979	Chevrolet	K20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1979	Chevrolet	K20 Suburban		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1979	Chevrolet	P20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1979	Chevrolet	P30		N/A	For vehicles with a GVW of 7,600 to 8,200 lbs, with a bore size of 1.25 inches, excluding Motorhome Chassis.
1979	GMC	C2500		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1979	GMC	C2500 Suburban		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1979	GMC	G3500		N/A	7,700 to 8,400 Lb. GVW, Bore: 1.25 In.
1979	GMC	K2500		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1979	GMC	K2500 Suburban		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1979	GMC	P2500		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1979	GMC	P3500		N/A	For vehicles with a GVW of 7,600 to 8,200 lbs, with a bore size of 1.25 inches, excluding Motorhome Chassis.
1978	Chevrolet	C20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1978	Chevrolet	C20 Suburban		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1978	Chevrolet	C30		N/A	Fitment: 6,600-8,200 Lb. GVW, 1.25 In. Bore
1978	Chevrolet	G30		N/A	7,700 to 8,400 Lb. GVW, Bore: 1.25 In.
1978	Chevrolet	K20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1978	Chevrolet	K20 Suburban		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1978	Chevrolet	P20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1978	Chevrolet	P30		N/A	For vehicles with a GVW of 7,600 to 8,200 lbs, with a bore size of 1.25 inches, excluding Motorhome Chassis.
1978	GMC	G35		N/A	7,700 to 8,400 Lb. GVW, Bore: 1.25 In.
1977	Chevrolet	C20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1977	Chevrolet	C20 Suburban		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1977	Chevrolet	C30		N/A	Fitment: 6,600-8,200 Lb. GVW, 1.25 In. Bore
1977	Chevrolet	G30		N/A	7,700 to 8,400 Lb. GVW, Bore: 1.25 In.
1977	Chevrolet	K20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1977	Chevrolet	K20 Suburban		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1977	Chevrolet	P20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1977	Chevrolet	P30		N/A	For vehicles with a GVW of 7,600 to 8,200 lbs, with a bore size of 1.25 inches, excluding Motorhome Chassis.
1977	GMC	G35		N/A	7,700 to 8,400 Lb. GVW, Bore: 1.25 In.
1976	Chevrolet	C10 Suburban		N/A	Fitment: Compatible with 13-inch brakes.
1976	Chevrolet	C20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1976	Chevrolet	C20 Suburban		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1976	Chevrolet	C30		N/A	Fitment: 6,600-8,200 Lb. GVW, 1.25 In. Bore
1976	Chevrolet	G30		N/A	7,700 to 8,400 Lb. GVW, Bore: 1.25 In.
1976	Chevrolet	K10 Suburban		N/A	Fitment: Compatible with 13-inch brakes.
1976	Chevrolet	K20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1976	Chevrolet	K20 Suburban		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1976	Chevrolet	P20		N/A	Brake Master Cylinder fits 13-inch brakes with a 1.25 inch bore size.
1976	Chevrolet	P30		N/A	For vehicles with a GVW of 7,600 to 8,200 lbs, with a bore size of 1.25 inches, excluding Motorhome Chassis.
1976	GMC	G35		N/A	7,700 to 8,400 Lb. GVW, Bore: 1.25 In.
1975	Chevrolet	C10 Suburban		N/A	Fitment: Compatible with 13-inch brakes.
1975	Chevrolet	C10 Suburban		N/A	3/4 Ton with 11" Brake Compatibility
1975	Chevrolet	C20		N/A	Verify vehicle compatibility before purchasing 1.25" bore size drum brake wheel cylinder.
1975	Chevrolet	C20 Suburban		N/A	Verify vehicle compatibility before purchasing 1.25" bore size drum brake wheel cylinder.
1975	Chevrolet	C30		N/A	Fitment: 6,600-8,200 Lb. GVW, 1.25 In. Bore
1975	Chevrolet	G30		N/A	6,400 to 8,400 Lb. GVW; Bore: 1.25 In.
1975	Chevrolet	K10 Suburban		N/A	Fitment: Compatible with 13-inch brakes.
1975	Chevrolet	K10 Suburban		N/A	3/4 Ton with 11" Brake Compatibility
1975	Chevrolet	K20		N/A	Verify vehicle compatibility before purchasing 1.25" bore size drum brake wheel cylinder.
1975	Chevrolet	K20 Suburban		N/A	Verify vehicle compatibility before purchasing 1.25" bore size drum brake wheel cylinder.
1975	Chevrolet	P20		N/A	Verify vehicle compatibility before purchasing 1.25" bore size drum brake wheel cylinder.
1975	Chevrolet	P30		N/A	For vehicles with a GVW of 7,600 to 8,200 lbs, with a bore size of 1.25 inches, excluding Motorhome Chassis.
1975	GMC	G35		N/A	6,400 to 8,400 Lb. GVW; Bore: 1.25 In.
1974	GMC	G35/G3500 Van		N/A	6,400 to 8,400 Lb. GVW; Bore: 1.25 In.; Power Brakes
1971	GMC	G35/G3500 Van		N/A	Fitment: 1.25 inch bore Power Brake Master Cylinder

* Always verify fitment with your vehicle's VIN if unsure. Submodel & trim restrictions may apply.

This part directly replaces or is cross-referenced with the following part numbers:

10-15341012661173013-1534130.660081800245818M922539075783-44008F101266M-86008M1583M900261MC101266

Cross-reference numbers are provided for identification purposes only. Always confirm fitment before ordering.